Those functions are going to be used for netdumps too. --- Makefile | 7 +- defs.h | 7 + kaslr_helper.c | 460 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ sadump.c | 486 ++++----------------------------------------------------- symbols.c | 6 +- 5 files changed, 511 insertions(+), 455 deletions(-) create mode 100644 kaslr_helper.c diff --git a/Makefile b/Makefile index bdc8321..f8647b3 100644 --- a/Makefile +++ b/Makefile @@ -71,7 +71,7 @@ CFILES=main.c tools.c global_data.c memory.c filesys.c help.c task.c \ xen_hyper.c xen_hyper_command.c xen_hyper_global_data.c \ xen_hyper_dump_tables.c kvmdump.c qemu.c qemu-load.c sadump.c ipcs.c \ ramdump.c vmware_vmss.c \ - xen_dom0.c + xen_dom0.c kaslr_helper.c SOURCE_FILES=${CFILES} ${GENERIC_HFILES} ${MCORE_HFILES} \ ${REDHAT_CFILES} ${REDHAT_HFILES} ${UNWIND_HFILES} \ @@ -90,7 +90,7 @@ OBJECT_FILES=main.o tools.o global_data.o memory.o filesys.o help.o task.o \ xen_hyper.o xen_hyper_command.o xen_hyper_global_data.o \ xen_hyper_dump_tables.o kvmdump.o qemu.o qemu-load.o sadump.o ipcs.o \ ramdump.o vmware_vmss.o \ - xen_dom0.o + xen_dom0.o kaslr_helper.o MEMORY_DRIVER_FILES=memory_driver/Makefile memory_driver/crash.c memory_driver/README @@ -517,6 +517,9 @@ ramdump.o: ${GENERIC_HFILES} ${REDHAT_HFILES} ramdump.c vmware_vmss.o: ${GENERIC_HFILES} ${VMWARE_HFILES} vmware_vmss.c ${CC} -c ${CRASH_CFLAGS} vmware_vmss.c ${WARNING_OPTIONS} ${WARNING_ERROR} +kaslr_helper.o: ${GENERIC_HFILES} kaslr_helper.c + ${CC} -c ${CRASH_CFLAGS} kaslr_helper.c ${WARNING_OPTIONS} ${WARNING_ERROR} + ${PROGRAM}: force @make --no-print-directory all diff --git a/defs.h b/defs.h index 7998ebf..808ac61 100644 --- a/defs.h +++ b/defs.h @@ -6334,6 +6334,7 @@ FILE *set_sadump_fp(FILE *); void get_sadump_regs(struct bt_info *bt, ulong *ipp, ulong *spp); void sadump_display_regs(int, FILE *); int sadump_phys_base(ulong *); +int sadump_set_phys_base(ulong); void sadump_show_diskset(void); int sadump_is_zero_excluded(void); void sadump_set_zero_excluded(void); @@ -6341,6 +6342,7 @@ void sadump_unset_zero_excluded(void); struct sadump_data; struct sadump_data *get_sadump_data(void); int sadump_calc_kaslr_offset(ulong *); +int sadump_get_cr3_idtr(ulong *, ulong *); /* * qemu.c @@ -6389,6 +6391,11 @@ uint vmware_vmss_page_size(void); int read_vmware_vmss(int, void *, int, ulong, physaddr_t); int write_vmware_vmss(int, void *, int, ulong, physaddr_t); +/* + * kaslr_helper.c + */ +int calc_kaslr_offset(ulong *, ulong *); + /* * gnu_binutils.c */ diff --git a/kaslr_helper.c b/kaslr_helper.c new file mode 100644 index 0000000..65256ab --- /dev/null +++ b/kaslr_helper.c @@ -0,0 +1,460 @@ +/* + * kaslr_helper - helper for kaslr offset calculation + * + * Copyright (c) 2011 FUJITSU LIMITED + * Copyright (c) 2018 Red Hat Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * Author: HATAYAMA Daisuke <d.hatayama(a)jp.fujitsu.com&gt; + */ + +#include "defs.h" +#include <elf.h> +#include <inttypes.h> + +#ifdef X86_64 +/* + * Get address of vector0 interrupt handler (Devide Error) from Interrupt + * Descriptor Table. + */ +static ulong +get_vec0_addr(ulong idtr) +{ + struct gate_struct64 { + uint16_t offset_low; + uint16_t segment; + uint32_t ist : 3, zero0 : 5, type : 5, dpl : 2, p : 1; + uint16_t offset_middle; + uint32_t offset_high; + uint32_t zero1; + } __attribute__((packed)) gate; + + readmem(idtr, PHYSADDR, &gate, sizeof(gate), "idt_table", FAULT_ON_ERROR); + + return ((ulong)gate.offset_high << 32) + + ((ulong)gate.offset_middle << 16) + + gate.offset_low; +} + +/* + * Parse a string of [size[KMG] ]offset[KMG] + * Import from Linux kernel(lib/cmdline.c) + */ +static ulong memparse(char *ptr, char **retptr) +{ + char *endptr; + + unsigned long long ret = strtoull(ptr, &endptr, 0); + + switch (*endptr) { + case 'E': + case 'e': + ret <<= 10; + case 'P': + case 'p': + ret <<= 10; + case 'T': + case 't': + ret <<= 10; + case 'G': + case 'g': + ret <<= 10; + case 'M': + case 'm': + ret <<= 10; + case 'K': + case 'k': + ret <<= 10; + endptr++; + default: + break; + } + + if (retptr) + *retptr = endptr; + + return ret; +} + +/* + * Find "elfcorehdr=" in the boot parameter of kernel and return the address + * of elfcorehdr. + */ +static ulong +get_elfcorehdr(ulong kaslr_offset) +{ + char cmdline[BUFSIZE], *ptr; + ulong cmdline_vaddr; + ulong cmdline_paddr; + ulong buf_vaddr, buf_paddr; + char *end; + ulong elfcorehdr_addr = 0, elfcorehdr_size = 0; + int verbose = CRASHDEBUG(1)? 1: 0; + + cmdline_vaddr = st->saved_command_line_vmlinux + kaslr_offset; + if (!kvtop(NULL, cmdline_vaddr, &cmdline_paddr, verbose)) + return 0; + + if (CRASHDEBUG(1)) { + fprintf(fp, "cmdline vaddr=%lx\n", cmdline_vaddr); + fprintf(fp, "cmdline paddr=%lx\n", cmdline_paddr); + } + + if (!readmem(cmdline_paddr, PHYSADDR, &buf_vaddr, sizeof(ulong), + "saved_command_line", RETURN_ON_ERROR)) + return 0; + + if (!kvtop(NULL, buf_vaddr, &buf_paddr, verbose)) + return 0; + + if (CRASHDEBUG(1)) { + fprintf(fp, "cmdline buffer vaddr=%lx\n", buf_vaddr); + fprintf(fp, "cmdline buffer paddr=%lx\n", buf_paddr); + } + + memset(cmdline, 0, BUFSIZE); + if (!readmem(buf_paddr, PHYSADDR, cmdline, BUFSIZE, + "saved_command_line", RETURN_ON_ERROR)) + return 0; + + ptr = strstr(cmdline, "elfcorehdr="); + if (!ptr) + return 0; + + if (CRASHDEBUG(1)) + fprintf(fp, "2nd kernel detected\n"); + + ptr += strlen("elfcorehdr="); + elfcorehdr_addr = memparse(ptr, &end); + if (*end == '@') { + elfcorehdr_size = elfcorehdr_addr; + elfcorehdr_addr = memparse(end + 1, &end); + } + + if (CRASHDEBUG(1)) { + fprintf(fp, "elfcorehdr_addr=%lx\n", elfcorehdr_addr); + fprintf(fp, "elfcorehdr_size=%lx\n", elfcorehdr_size); + } + + return elfcorehdr_addr; +} + + /* + * Get vmcoreinfo from elfcorehdr. + * Some codes are imported from Linux kernel(fs/proc/vmcore.c) + */ +static int +get_vmcoreinfo(ulong elfcorehdr, ulong *addr, int *len) +{ + unsigned char e_ident[EI_NIDENT]; + Elf64_Ehdr ehdr; + Elf64_Phdr phdr; + Elf64_Nhdr nhdr; + ulong ptr; + ulong nhdr_offset = 0; + int i; + + if (!readmem(elfcorehdr, PHYSADDR, e_ident, EI_NIDENT, + "EI_NIDENT", RETURN_ON_ERROR)) + return FALSE; + + if (e_ident[EI_CLASS] != ELFCLASS64) { + error(INFO, "Only ELFCLASS64 is supportd\n"); + return FALSE; + } + + if (!readmem(elfcorehdr, PHYSADDR, &ehdr, sizeof(ehdr), + "Elf64_Ehdr", RETURN_ON_ERROR)) + return FALSE; + + /* Sanity Check */ + if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 || + (ehdr.e_type != ET_CORE) || + ehdr.e_ident[EI_CLASS] != ELFCLASS64 || + ehdr.e_ident[EI_VERSION] != EV_CURRENT || + ehdr.e_version != EV_CURRENT || + ehdr.e_ehsize != sizeof(Elf64_Ehdr) || + ehdr.e_phentsize != sizeof(Elf64_Phdr) || + ehdr.e_phnum == 0) { + error(INFO, "Invalid elf header\n"); + return FALSE; + } + + ptr = elfcorehdr + ehdr.e_phoff; + for (i = 0; i < ehdr.e_phnum; i++) { + ulong offset; + char name[16]; + + if (!readmem(ptr, PHYSADDR, &phdr, sizeof(phdr), + "Elf64_Phdr", RETURN_ON_ERROR)) + return FALSE; + + ptr += sizeof(phdr); + if (phdr.p_type != PT_NOTE) + continue; + + offset = phdr.p_offset; + if (!readmem(offset, PHYSADDR, &nhdr, sizeof(nhdr), + "Elf64_Nhdr", RETURN_ON_ERROR)) + return FALSE; + + offset += DIV_ROUND_UP(sizeof(Elf64_Nhdr), sizeof(Elf64_Word))* + sizeof(Elf64_Word); + memset(name, 0, sizeof(name)); + if (!readmem(offset, PHYSADDR, name, sizeof(name), + "Elf64_Nhdr name", RETURN_ON_ERROR)) + return FALSE; + + if(!strcmp(name, "VMCOREINFO")) { + nhdr_offset = offset; + break; + } + } + + if (!nhdr_offset) + return FALSE; + + *addr = nhdr_offset + + DIV_ROUND_UP(nhdr.n_namesz, sizeof(Elf64_Word))* + sizeof(Elf64_Word); + *len = nhdr.n_descsz; + + if (CRASHDEBUG(1)) { + fprintf(fp, "vmcoreinfo addr=%lx\n", *addr); + fprintf(fp, "vmcoreinfo len=%d\n", *len); + } + + return TRUE; +} + +/* + * Check if current kaslr_offset/phys_base is for 1st kernel or 2nd kernel. + * If we are in 2nd kernel, get kaslr_offset/phys_base from vmcoreinfo. + * + * 1. Get command line and try to retrieve "elfcorehdr=" boot parameter + * 2. If "elfcorehdr=" is not found in command line, we are in 1st kernel. + * There is nothing to do. + * 3. If "elfcorehdr=" is found, we are in 2nd kernel. Find vmcoreinfo + * using "elfcorehdr=" and retrieve kaslr_offset/phys_base from vmcoreinfo. + */ +static int +get_kaslr_offset_from_vmcoreinfo(ulong orig_kaslr_offset, + ulong *kaslr_offset, ulong *phys_base) +{ + ulong elfcorehdr_addr = 0; + ulong vmcoreinfo_addr; + int vmcoreinfo_len; + char *buf, *pos; + int ret = FALSE; + + /* Find "elfcorehdr=" in the kernel boot parameter */ + elfcorehdr_addr = get_elfcorehdr(orig_kaslr_offset); + if (!elfcorehdr_addr) + return FALSE; + + /* Get vmcoreinfo from the address of "elfcorehdr=" */ + if (!get_vmcoreinfo(elfcorehdr_addr, &vmcoreinfo_addr, &vmcoreinfo_len)) + return FALSE; + + if (!vmcoreinfo_len) + return FALSE; + + if (CRASHDEBUG(1)) + fprintf(fp, "Find vmcoreinfo in kdump memory\n"); + + buf = GETBUF(vmcoreinfo_len); + if (!readmem(vmcoreinfo_addr, PHYSADDR, buf, vmcoreinfo_len, + "vmcoreinfo", RETURN_ON_ERROR)) + goto quit; + + /* Get phys_base form vmcoreinfo */ + pos = strstr(buf, "NUMBER(phys_base)="); + if (!pos) + goto quit; + *phys_base = strtoull(pos + strlen("NUMBER(phys_base)="), NULL, 0); + + /* Get kaslr_offset form vmcoreinfo */ + pos = strstr(buf, "KERNELOFFSET="); + if (!pos) + goto quit; + *kaslr_offset = strtoull(pos + strlen("KERNELOFFSET="), NULL, 16); + + ret = TRUE; + +quit: + FREEBUF(buf); + return ret; +} + +/* + * Calculate kaslr_offset and phys_base + * + * kaslr_offset: + * The difference between original address in System.map or vmlinux and + * actual address placed randomly by kaslr feature. To be more accurate, + * kaslr_offset = actual address - original address + * + * phys_base: + * Physical address where the kerenel is placed. In other words, it's a + * physical address of __START_KERNEL_map. This is also decided randomly by + * kaslr. + * + * kaslr offset and phys_base are calculated as follows: + * + * kaslr_offset: + * 1) Get IDTR and CR3 value from the dump header. + * 2) Get a virtual address of IDT from IDTR value + * --- (A) + * 3) Translate (A) to physical address using CR3, the upper 52 bits + * of which points a top of page table. + * --- (B) + * 4) Get an address of vector0 (Devide Error) interrupt handler from + * IDT, which are pointed by (B). + * --- (C) + * 5) Get an address of symbol "divide_error" form vmlinux + * --- (D) + * + * Now we have two addresses: + * (C)-> Actual address of "divide_error" + * (D)-> Original address of "divide_error" in the vmlinux + * + * kaslr_offset can be calculated by the difference between these two + * value. + * + * phys_base; + * 1) Get IDT virtual address from vmlinux + * --- (E) + * + * So phys_base can be calculated using relationship of directly mapped + * address. + * + * phys_base = + * Physical address(B) - + * (Virtual address(E) + kaslr_offset - __START_KERNEL_map) + * + * Note that the address (A) cannot be used instead of (E) because (A) is + * not direct map address, it's a fixed map address. + * + * This solution works in most every case, but does not work in the + * following case. + * + * 1) If the dump is captured on early stage of kernel boot, IDTR points + * early IDT table(early_idts) instead of normal IDT(idt_table). + * 2) If the dump is captured whle kdump is working, IDTR points + * IDT table of 2nd kernel, not 1st kernel. + * + * Current implementation does not support the case 1), need + * enhancement in the future. For the case 2), get kaslr_offset and + * phys_base as follows. + * + * 1) Get kaslr_offset and phys_base using the above solution. + * 2) Get kernel boot parameter from "saved_command_line" + * 3) If "elfcorehdr=" is not included in boot parameter, we are in the + * first kernel, nothing to do any more. + * 4) If "elfcorehdr=" is included in boot parameter, we are in the 2nd + * kernel. Retrieve vmcoreinfo from address of "elfcorehdr=" and + * get kaslr_offset and phys_base from vmcoreinfo. + */ +#define PTI_USER_PGTABLE_BIT PAGE_SHIFT +#define PTI_USER_PGTABLE_MASK (1 << PTI_USER_PGTABLE_BIT) +#define CR3_PCID_MASK 0xFFFull +int +calc_kaslr_offset(ulong *kaslr_offset, ulong *phys_base) +{ + uint64_t cr3 = 0, idtr = 0, pgd = 0, idtr_paddr; + ulong divide_error_vmcore; + ulong kaslr_offset_kdump, phys_base_kdump; + int ret = FALSE; + int verbose = CRASHDEBUG(1)? 1: 0; + + if (!machine_type("X86_64")) + return FALSE; + + if (SADUMP_DUMPFILE() && !sadump_get_cr3_idtr(&cr3, &idtr)) { + return FALSE; + } + + if (st->pti_init_vmlinux || st->kaiser_init_vmlinux) + pgd = cr3 & ~(CR3_PCID_MASK|PTI_USER_PGTABLE_MASK); + else + pgd = cr3 & ~CR3_PCID_MASK; + + /* + * Set up for kvtop. + * + * calc_kaslr_offset() is called before machdep_init(PRE_GDB), so some + * variables are not initialized yet. Set up them here to call kvtop(). + * + * TODO: XEN and 5-level is not supported + */ + vt->kernel_pgd[0] = pgd; + machdep->last_pgd_read = vt->kernel_pgd[0]; + machdep->machspec->physical_mask_shift = __PHYSICAL_MASK_SHIFT_2_6; + machdep->machspec->pgdir_shift = PGDIR_SHIFT; + machdep->machspec->ptrs_per_pgd = PTRS_PER_PGD; + if (!readmem(pgd, PHYSADDR, machdep->pgd, PAGESIZE(), + "pgd", RETURN_ON_ERROR)) + goto quit; + + /* Convert virtual address of IDT table to physical address */ + if (!kvtop(NULL, idtr, &idtr_paddr, verbose)) + goto quit; + + /* Now we can calculate kaslr_offset and phys_base */ + divide_error_vmcore = get_vec0_addr(idtr_paddr); + *kaslr_offset = divide_error_vmcore - st->divide_error_vmlinux; + *phys_base = idtr_paddr - + (st->idt_table_vmlinux + *kaslr_offset - __START_KERNEL_map); + + if (CRASHDEBUG(1)) { + fprintf(fp, "calc_kaslr_offset: idtr=%lx\n", idtr); + fprintf(fp, "calc_kaslr_offset: pgd=%lx\n", pgd); + fprintf(fp, "calc_kaslr_offset: idtr(phys)=%lx\n", idtr_paddr); + fprintf(fp, "calc_kaslr_offset: divide_error(vmlinux): %lx\n", + st->divide_error_vmlinux); + fprintf(fp, "calc_kaslr_offset: divide_error(vmcore): %lx\n", + divide_error_vmcore); + } + + /* + * Check if current kaslr_offset/phys_base is for 1st kernel or 2nd + * kernel. If we are in 2nd kernel, get kaslr_offset/phys_base + * from vmcoreinfo + */ + if (get_kaslr_offset_from_vmcoreinfo( + *kaslr_offset, &kaslr_offset_kdump, &phys_base_kdump)) { + *kaslr_offset = kaslr_offset_kdump; + *phys_base = phys_base_kdump; + } else if (CRASHDEBUG(1)) { + fprintf(fp, "kaslr_helper: failed to determine which kernel was running at crash,\n"); + fprintf(fp, "kaslr_helper: asssuming the kdump 1st kernel.\n"); + } + + if (CRASHDEBUG(1)) { + fprintf(fp, "calc_kaslr_offset: kaslr_offset=%lx\n", + *kaslr_offset); + fprintf(fp, "calc_kaslr_offset: phys_base=%lx\n", *phys_base); + } + + ret = TRUE; +quit: + vt->kernel_pgd[0] = 0; + machdep->last_pgd_read = 0; + return ret; +} +#else +int +calc_kaslr_offset(ulong *kaslr_offset, ulong *phys_page) +{ + return FALSE; +} +#endif /* X86_64 */ diff --git a/sadump.c b/sadump.c index d19b40a..a37602b 100644 --- a/sadump.c +++ b/sadump.c @@ -1569,6 +1569,13 @@ int sadump_phys_base(ulong *phys_base) return FALSE; } +int sadump_set_phys_base(ulong phys_base) +{ + sd->phys_base = phys_base; + + return TRUE; +} + /* * Used by "sys" command to show diskset disk names. */ @@ -1656,466 +1663,41 @@ get_sadump_data(void) static int get_sadump_smram_cpu_state_any(struct sadump_smram_cpu_state *smram) { - ulong offset; - struct sadump_header *sh = sd->dump_header; - int apicid; - struct sadump_smram_cpu_state scs, zero; - - offset = sd->sub_hdr_offset + sizeof(uint32_t) + - sd->dump_header->nr_cpus * sizeof(struct sadump_apic_state); - - memset(&zero, 0, sizeof(zero)); - - for (apicid = 0; apicid < sh->nr_cpus; ++apicid) { - if (!read_device(&scs, sizeof(scs), &offset)) { - error(INFO, "sadump: cannot read sub header " - "cpu_state\n"); - return FALSE; - } - if (memcmp(&scs, &zero, sizeof(scs)) != 0) { - *smram = scs; - return TRUE; - } - } - - return FALSE; -} - -/* - * Get address of vector0 interrupt handler (Devide Error) from Interrupt - * Descriptor Table. - */ -static ulong -get_vec0_addr(ulong idtr) -{ - struct gate_struct64 { - uint16_t offset_low; - uint16_t segment; - uint32_t ist : 3, zero0 : 5, type : 5, dpl : 2, p : 1; - uint16_t offset_middle; - uint32_t offset_high; - uint32_t zero1; - } __attribute__((packed)) gate; - - readmem(idtr, PHYSADDR, &gate, sizeof(gate), "idt_table", FAULT_ON_ERROR); - - return ((ulong)gate.offset_high << 32) - + ((ulong)gate.offset_middle << 16) - + gate.offset_low; -} - -/* - * Parse a string of [size[KMG] ]offset[KMG] - * Import from Linux kernel(lib/cmdline.c) - */ -static ulong memparse(char *ptr, char **retptr) -{ - char *endptr; - - unsigned long long ret = strtoull(ptr, &endptr, 0); - - switch (*endptr) { - case 'E': - case 'e': - ret <<= 10; - case 'P': - case 'p': - ret <<= 10; - case 'T': - case 't': - ret <<= 10; - case 'G': - case 'g': - ret <<= 10; - case 'M': - case 'm': - ret <<= 10; - case 'K': - case 'k': - ret <<= 10; - endptr++; - default: - break; - } - - if (retptr) - *retptr = endptr; - - return ret; -} - -/* - * Find "elfcorehdr=" in the boot parameter of kernel and return the address - * of elfcorehdr. - */ -static ulong -get_elfcorehdr(ulong kaslr_offset) -{ - char cmdline[BUFSIZE], *ptr; - ulong cmdline_vaddr; - ulong cmdline_paddr; - ulong buf_vaddr, buf_paddr; - char *end; - ulong elfcorehdr_addr = 0, elfcorehdr_size = 0; - int verbose = CRASHDEBUG(1)? 1: 0; - - cmdline_vaddr = st->saved_command_line_vmlinux + kaslr_offset; - if (!kvtop(NULL, cmdline_vaddr, &cmdline_paddr, verbose)) - return 0; - - if (CRASHDEBUG(1)) { - fprintf(fp, "cmdline vaddr=%lx\n", cmdline_vaddr); - fprintf(fp, "cmdline paddr=%lx\n", cmdline_paddr); - } - - if (!readmem(cmdline_paddr, PHYSADDR, &buf_vaddr, sizeof(ulong), - "saved_command_line", RETURN_ON_ERROR)) - return 0; - - if (!kvtop(NULL, buf_vaddr, &buf_paddr, verbose)) - return 0; - - if (CRASHDEBUG(1)) { - fprintf(fp, "cmdline buffer vaddr=%lx\n", buf_vaddr); - fprintf(fp, "cmdline buffer paddr=%lx\n", buf_paddr); - } - - memset(cmdline, 0, BUFSIZE); - if (!readmem(buf_paddr, PHYSADDR, cmdline, BUFSIZE, - "saved_command_line", RETURN_ON_ERROR)) - return 0; - - ptr = strstr(cmdline, "elfcorehdr="); - if (!ptr) - return 0; - - if (CRASHDEBUG(1)) - fprintf(fp, "2nd kernel detected\n"); - - ptr += strlen("elfcorehdr="); - elfcorehdr_addr = memparse(ptr, &end); - if (*end == '@') { - elfcorehdr_size = elfcorehdr_addr; - elfcorehdr_addr = memparse(end + 1, &end); - } - - if (CRASHDEBUG(1)) { - fprintf(fp, "elfcorehdr_addr=%lx\n", elfcorehdr_addr); - fprintf(fp, "elfcorehdr_size=%lx\n", elfcorehdr_size); - } - - return elfcorehdr_addr; -} - - /* - * Get vmcoreinfo from elfcorehdr. - * Some codes are imported from Linux kernel(fs/proc/vmcore.c) - */ -static int -get_vmcoreinfo(ulong elfcorehdr, ulong *addr, int *len) -{ - unsigned char e_ident[EI_NIDENT]; - Elf64_Ehdr ehdr; - Elf64_Phdr phdr; - Elf64_Nhdr nhdr; - ulong ptr; - ulong nhdr_offset = 0; - int i; - - if (!readmem(elfcorehdr, PHYSADDR, e_ident, EI_NIDENT, - "EI_NIDENT", RETURN_ON_ERROR)) - return FALSE; - - if (e_ident[EI_CLASS] != ELFCLASS64) { - error(INFO, "Only ELFCLASS64 is supportd\n"); - return FALSE; - } - - if (!readmem(elfcorehdr, PHYSADDR, &ehdr, sizeof(ehdr), - "Elf64_Ehdr", RETURN_ON_ERROR)) - return FALSE; - - /* Sanity Check */ - if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 || - (ehdr.e_type != ET_CORE) || - ehdr.e_ident[EI_CLASS] != ELFCLASS64 || - ehdr.e_ident[EI_VERSION] != EV_CURRENT || - ehdr.e_version != EV_CURRENT || - ehdr.e_ehsize != sizeof(Elf64_Ehdr) || - ehdr.e_phentsize != sizeof(Elf64_Phdr) || - ehdr.e_phnum == 0) { - error(INFO, "Invalid elf header\n"); - return FALSE; - } - - ptr = elfcorehdr + ehdr.e_phoff; - for (i = 0; i < ehdr.e_phnum; i++) { - ulong offset; - char name[16]; - - if (!readmem(ptr, PHYSADDR, &phdr, sizeof(phdr), - "Elf64_Phdr", RETURN_ON_ERROR)) - return FALSE; - - ptr += sizeof(phdr); - if (phdr.p_type != PT_NOTE) - continue; - - offset = phdr.p_offset; - if (!readmem(offset, PHYSADDR, &nhdr, sizeof(nhdr), - "Elf64_Nhdr", RETURN_ON_ERROR)) - return FALSE; - - offset += DIV_ROUND_UP(sizeof(Elf64_Nhdr), sizeof(Elf64_Word))* - sizeof(Elf64_Word); - memset(name, 0, sizeof(name)); - if (!readmem(offset, PHYSADDR, name, sizeof(name), - "Elf64_Nhdr name", RETURN_ON_ERROR)) - return FALSE; - - if(!strcmp(name, "VMCOREINFO")) { - nhdr_offset = offset; - break; - } - } - - if (!nhdr_offset) - return FALSE; - - *addr = nhdr_offset + - DIV_ROUND_UP(nhdr.n_namesz, sizeof(Elf64_Word))* - sizeof(Elf64_Word); - *len = nhdr.n_descsz; - - if (CRASHDEBUG(1)) { - fprintf(fp, "vmcoreinfo addr=%lx\n", *addr); - fprintf(fp, "vmcoreinfo len=%d\n", *len); - } - - return TRUE; -} - -/* - * Check if current kaslr_offset/phys_base is for 1st kernel or 2nd kernel. - * If we are in 2nd kernel, get kaslr_offset/phys_base from vmcoreinfo. - * - * 1. Get command line and try to retrieve "elfcorehdr=" boot parameter - * 2. If "elfcorehdr=" is not found in command line, we are in 1st kernel. - * There is nothing to do. - * 3. If "elfcorehdr=" is found, we are in 2nd kernel. Find vmcoreinfo - * using "elfcorehdr=" and retrieve kaslr_offset/phys_base from vmcoreinfo. - */ -static int -get_kaslr_offset_from_vmcoreinfo(ulong orig_kaslr_offset, - ulong *kaslr_offset, ulong *phys_base) -{ - ulong elfcorehdr_addr = 0; - ulong vmcoreinfo_addr; - int vmcoreinfo_len; - char *buf, *pos; - int ret = FALSE; - - /* Find "elfcorehdr=" in the kernel boot parameter */ - elfcorehdr_addr = get_elfcorehdr(orig_kaslr_offset); - if (!elfcorehdr_addr) - return FALSE; - - /* Get vmcoreinfo from the address of "elfcorehdr=" */ - if (!get_vmcoreinfo(elfcorehdr_addr, &vmcoreinfo_addr, &vmcoreinfo_len)) - return FALSE; - - if (!vmcoreinfo_len) - return FALSE; - - if (CRASHDEBUG(1)) - fprintf(fp, "Find vmcoreinfo in kdump memory\n"); - - buf = GETBUF(vmcoreinfo_len); - if (!readmem(vmcoreinfo_addr, PHYSADDR, buf, vmcoreinfo_len, - "vmcoreinfo", RETURN_ON_ERROR)) - goto quit; - - /* Get phys_base form vmcoreinfo */ - pos = strstr(buf, "NUMBER(phys_base)="); - if (!pos) - goto quit; - *phys_base = strtoull(pos + strlen("NUMBER(phys_base)="), NULL, 0); - - /* Get kaslr_offset form vmcoreinfo */ - pos = strstr(buf, "KERNELOFFSET="); - if (!pos) - goto quit; - *kaslr_offset = strtoull(pos + strlen("KERNELOFFSET="), NULL, 16); - - ret = TRUE; - -quit: - FREEBUF(buf); - return ret; + ulong offset; + struct sadump_header *sh = sd->dump_header; + int apicid; + struct sadump_smram_cpu_state scs, zero; + + offset = sd->sub_hdr_offset + sizeof(uint32_t) + + sd->dump_header->nr_cpus * sizeof(struct sadump_apic_state); + + memset(&zero, 0, sizeof(zero)); + + for (apicid = 0; apicid < sh->nr_cpus; ++apicid) { + if (!read_device(&scs, sizeof(scs), &offset)) { + error(INFO, "sadump: cannot read sub header " + "cpu_state\n"); + return FALSE; + } + if (memcmp(&scs, &zero, sizeof(scs)) != 0) { + *smram = scs; + return TRUE; + } + } + + return FALSE; } -/* - * Calculate kaslr_offset and phys_base - * - * kaslr_offset: - * The difference between original address in System.map or vmlinux and - * actual address placed randomly by kaslr feature. To be more accurate, - * kaslr_offset = actual address - original address - * - * phys_base: - * Physical address where the kerenel is placed. In other words, it's a - * physical address of __START_KERNEL_map. This is also decided randomly by - * kaslr. - * - * kaslr offset and phys_base are calculated as follows: - * - * kaslr_offset: - * 1) Get IDTR and CR3 value from the dump header. - * 2) Get a virtual address of IDT from IDTR value - * --- (A) - * 3) Translate (A) to physical address using CR3, the upper 52 bits - * of which points a top of page table. - * --- (B) - * 4) Get an address of vector0 (Devide Error) interrupt handler from - * IDT, which are pointed by (B). - * --- (C) - * 5) Get an address of symbol "divide_error" form vmlinux - * --- (D) - * - * Now we have two addresses: - * (C)-> Actual address of "divide_error" - * (D)-> Original address of "divide_error" in the vmlinux - * - * kaslr_offset can be calculated by the difference between these two - * value. - * - * phys_base; - * 1) Get IDT virtual address from vmlinux - * --- (E) - * - * So phys_base can be calculated using relationship of directly mapped - * address. - * - * phys_base = - * Physical address(B) - - * (Virtual address(E) + kaslr_offset - __START_KERNEL_map) - * - * Note that the address (A) cannot be used instead of (E) because (A) is - * not direct map address, it's a fixed map address. - * - * This solution works in most every case, but does not work in the - * following case. - * - * 1) If the dump is captured on early stage of kernel boot, IDTR points - * early IDT table(early_idts) instead of normal IDT(idt_table). - * 2) If the dump is captured whle kdump is working, IDTR points - * IDT table of 2nd kernel, not 1st kernel. - * - * Current implementation does not support the case 1), need - * enhancement in the future. For the case 2), get kaslr_offset and - * phys_base as follows. - * - * 1) Get kaslr_offset and phys_base using the above solution. - * 2) Get kernel boot parameter from "saved_command_line" - * 3) If "elfcorehdr=" is not included in boot parameter, we are in the - * first kernel, nothing to do any more. - * 4) If "elfcorehdr=" is included in boot parameter, we are in the 2nd - * kernel. Retrieve vmcoreinfo from address of "elfcorehdr=" and - * get kaslr_offset and phys_base from vmcoreinfo. - */ -#define PTI_USER_PGTABLE_BIT PAGE_SHIFT -#define PTI_USER_PGTABLE_MASK (1 << PTI_USER_PGTABLE_BIT) -#define CR3_PCID_MASK 0xFFFull -int -sadump_calc_kaslr_offset(ulong *kaslr_offset) +int sadump_get_cr3_idtr(ulong *cr3, ulong *idtr) { - ulong phys_base = 0; struct sadump_smram_cpu_state scs; - uint64_t idtr = 0, pgd = 0, idtr_paddr; - ulong divide_error_vmcore; - ulong kaslr_offset_kdump, phys_base_kdump; - int ret = FALSE; - int verbose = CRASHDEBUG(1)? 1: 0; - - if (!machine_type("X86_64")) - return FALSE; memset(&scs, 0, sizeof(scs)); get_sadump_smram_cpu_state_any(&scs); - if (st->pti_init_vmlinux || st->kaiser_init_vmlinux) - pgd = scs.Cr3 & ~(CR3_PCID_MASK|PTI_USER_PGTABLE_MASK); - else - pgd = scs.Cr3 & ~CR3_PCID_MASK; - idtr = ((uint64_t)scs.IdtUpper)<<32 | (uint64_t)scs.IdtLower; - /* - * Set up for kvtop. - * - * calc_kaslr_offset() is called before machdep_init(PRE_GDB), so some - * variables are not initialized yet. Set up them here to call kvtop(). - * - * TODO: XEN and 5-level is not supported - */ - vt->kernel_pgd[0] = pgd; - machdep->last_pgd_read = vt->kernel_pgd[0]; - machdep->machspec->physical_mask_shift = __PHYSICAL_MASK_SHIFT_2_6; - machdep->machspec->pgdir_shift = PGDIR_SHIFT; - machdep->machspec->ptrs_per_pgd = PTRS_PER_PGD; - if (!readmem(pgd, PHYSADDR, machdep->pgd, PAGESIZE(), - "pgd", RETURN_ON_ERROR)) - goto quit; - - /* Convert virtual address of IDT table to physical address */ - if (!kvtop(NULL, idtr, &idtr_paddr, verbose)) - goto quit; - - /* Now we can calculate kaslr_offset and phys_base */ - divide_error_vmcore = get_vec0_addr(idtr_paddr); - *kaslr_offset = divide_error_vmcore - st->divide_error_vmlinux; - phys_base = idtr_paddr - - (st->idt_table_vmlinux + *kaslr_offset - __START_KERNEL_map); - - if (CRASHDEBUG(1)) { - fprintf(fp, "calc_kaslr_offset: idtr=%lx\n", idtr); - fprintf(fp, "calc_kaslr_offset: pgd=%lx\n", pgd); - fprintf(fp, "calc_kaslr_offset: idtr(phys)=%lx\n", idtr_paddr); - fprintf(fp, "calc_kaslr_offset: divide_error(vmlinux): %lx\n", - st->divide_error_vmlinux); - fprintf(fp, "calc_kaslr_offset: divide_error(vmcore): %lx\n", - divide_error_vmcore); - } - - /* - * Check if current kaslr_offset/phys_base is for 1st kernel or 2nd - * kernel. If we are in 2nd kernel, get kaslr_offset/phys_base - * from vmcoreinfo - */ - if (get_kaslr_offset_from_vmcoreinfo( - *kaslr_offset, &kaslr_offset_kdump, &phys_base_kdump)) { - *kaslr_offset = kaslr_offset_kdump; - phys_base = phys_base_kdump; - } else if (CRASHDEBUG(1)) { - fprintf(fp, "sadump: failed to determine which kernel was running at crash,\n"); - fprintf(fp, "sadump: asssuming the kdump 1st kernel.\n"); - } + *cr3 = scs.Cr3; + *idtr = ((uint64_t)scs.IdtUpper)<<32 | (uint64_t)scs.IdtLower; - if (CRASHDEBUG(1)) { - fprintf(fp, "calc_kaslr_offset: kaslr_offset=%lx\n", - *kaslr_offset); - fprintf(fp, "calc_kaslr_offset: phys_base=%lx\n", phys_base); - } - - sd->phys_base = phys_base; - ret = TRUE; -quit: - vt->kernel_pgd[0] = 0; - machdep->last_pgd_read = 0; - return ret; -} -#else -int -sadump_calc_kaslr_offset(ulong *kaslr_offset) -{ - return FALSE; + return TRUE; } #endif /* X86_64 */ diff --git a/symbols.c b/symbols.c index 7910f53..54aa5b2 100644 --- a/symbols.c +++ b/symbols.c @@ -642,14 +642,18 @@ derive_kaslr_offset(bfd *abfd, int dynamic, bfd_byte *start, bfd_byte *end, if (SADUMP_DUMPFILE()) { ulong kaslr_offset = 0; + ulong phys_base = 0; - sadump_calc_kaslr_offset(&kaslr_offset); + calc_kaslr_offset(&kaslr_offset, &phys_base); if (kaslr_offset) { kt->relocate = kaslr_offset * -1; kt->flags |= RELOC_SET; } + if (phys_base) + sadump_set_phys_base(phys_base); + return; } -- 2.14.3

On Thu, Mar 22, 2018 at 06:38:43AM +0000, Hatayama, Daisuke wrote: OK, thanks. I've just sent a fourth of the patchset which, in addition to implementing support for VMware VMSS dumps, it fixes the missing brackets and updates the copyright notices. Perhaps you may want to try directly with that one. Sergio.

If a QEMU ELF dump from a KASLR-enabled kernel is missing the vmcoreinfo data, try to calculate phys_base and kaslr_offset by using the technique developed by Takao Indoh. --- defs.h | 6 ++++++ kaslr_helper.c | 25 +++++++++++++++++++++++-- netdump.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ netdump.h | 1 + symbols.c | 20 ++++++++++++++------ x86_64.c | 17 +++++++++++++++-- 6 files changed, 113 insertions(+), 10 deletions(-) diff --git a/defs.h b/defs.h index c5252f6..ec2d61c 100644 --- a/defs.h +++ b/defs.h @@ -283,6 +283,8 @@ struct number_option { #define LKCD_KERNTYPES() (pc->flags & KERNTYPES) #define KVMDUMP_DUMPFILE() (pc->flags & KVMDUMP) #define SADUMP_DUMPFILE() (pc->flags & SADUMP) +#define QEMU_MEM_DUMP_NO_VMCOREINFO() \ + ((pc->flags2 & (QEMU_MEM_DUMP_ELF)) && !(pc->flags2 & VMCOREINFO)) #define NETDUMP_LOCAL (0x1) /* netdump_data flags */ #define NETDUMP_REMOTE (0x2) @@ -6226,6 +6228,8 @@ int get_netdump_arch(void); int exist_regs_in_elf_notes(struct task_context *); void *get_regs_from_elf_notes(struct task_context *); void map_cpus_to_prstatus(void); +int kdump_phys_base(ulong *); +int kdump_set_phys_base(ulong); int arm_kdump_phys_base(ulong *); int is_proc_kcore(char *, ulong); int proc_kcore_init(FILE *); @@ -6237,6 +6241,8 @@ void kdump_backup_region_init(void); void display_regs_from_elf_notes(int, FILE *); void display_ELF_note(int, int, void *, FILE *); void *netdump_get_prstatus_percpu(int); +int kdump_kaslr_check(void); +QEMUCPUState *kdump_get_qemucpustate(int); #define PRSTATUS_NOTE (1) #define QEMU_NOTE (2) diff --git a/kaslr_helper.c b/kaslr_helper.c index 65256ab..d02ef72 100644 --- a/kaslr_helper.c +++ b/kaslr_helper.c @@ -236,6 +236,22 @@ get_vmcoreinfo(ulong elfcorehdr, ulong *addr, int *len) return TRUE; } +static int +qemu_get_cr3_idtr(ulong *cr3, ulong *idtr) +{ + QEMUCPUState *cpustat; + + cpustat = kdump_get_qemucpustate(0); + if (!cpustat) { + return FALSE; + } + + *cr3 = cpustat->cr[3]; + *idtr = cpustat->idt.base; + + return TRUE; +} + /* * Check if current kaslr_offset/phys_base is for 1st kernel or 2nd kernel. * If we are in 2nd kernel, get kaslr_offset/phys_base from vmcoreinfo. @@ -379,9 +395,14 @@ calc_kaslr_offset(ulong *kaslr_offset, ulong *phys_base) if (!machine_type("X86_64")) return FALSE; - if (SADUMP_DUMPFILE() && !sadump_get_cr3_idtr(&cr3, &idtr)) { + if (SADUMP_DUMPFILE()) { + if (!sadump_get_cr3_idtr(&cr3, &idtr)) + return FALSE; + } else if (QEMU_MEM_DUMP_NO_VMCOREINFO()) { + if (!qemu_get_cr3_idtr(&cr3, &idtr)) + return FALSE; + } else return FALSE; - } if (st->pti_init_vmlinux || st->kaiser_init_vmlinux) pgd = cr3 & ~(CR3_PCID_MASK|PTI_USER_PGTABLE_MASK); diff --git a/netdump.c b/netdump.c index 6cf7ca8..0f7c884 100644 --- a/netdump.c +++ b/netdump.c @@ -3999,6 +3999,26 @@ no_nt_prstatus_exists: return pt_regs; } +int kdump_phys_base(ulong *phys_base) +{ + if (!kdump_kaslr_check()) + return FALSE; + + *phys_base = nd->phys_base; + + return TRUE; +} + +int kdump_set_phys_base(ulong phys_base) +{ + if (!kdump_kaslr_check()) + return FALSE; + + nd->phys_base = phys_base; + + return TRUE; +} + /* * In case of ARM we need to determine correct PHYS_OFFSET from the kdump file. * This is done by taking lowest physical address (LMA) from given load @@ -4713,3 +4733,37 @@ error(INFO, "%s: backup region is used: %llx\n", typename, backup_offset + total error: error(WARNING, "failed to init kexec backup region\n"); } + +int +kdump_kaslr_check(void) +{ + if (!QEMU_MEM_DUMP_NO_VMCOREINFO()) + return FALSE; + + /* If vmcore has QEMU note, need to calculate kaslr offset */ + if (nd->num_qemu_notes) + return TRUE; + else + return FALSE; +} + +#ifdef X86_64 +QEMUCPUState * kdump_get_qemucpustate(int cpu) +{ + if (cpu >= nd->num_qemu_notes) { + if (CRASHDEBUG(1)) + error(INFO, + "Invalid index for QEMU Note: %d (>= %d)\n", + cpu, nd->num_qemu_notes); + return NULL; + } + + if (!nd->elf64 || (nd->elf64->e_machine != EM_X86_64)) { + if (CRASHDEBUG(1)) + error(INFO, "Only x86_64 64bit is supported.\n"); + return NULL; + } + + return (QEMUCPUState *)nd->nt_qemu_percpu[cpu]; +} +#endif diff --git a/netdump.h b/netdump.h index 87d51ca..5474593 100644 --- a/netdump.h +++ b/netdump.h @@ -78,6 +78,7 @@ struct vmcore_data { ulong backup_src_size; ulonglong backup_offset; ulong arch_data; + ulong phys_base; }; #define DUMP_ELF_INCOMPLETE 0x1 /* dumpfile is incomplete */ diff --git a/symbols.c b/symbols.c index 54aa5b2..348d9ae 100644 --- a/symbols.c +++ b/symbols.c @@ -610,7 +610,11 @@ kaslr_init(void) st->_stext_vmlinux = UNINITIALIZED; } - if (KDUMP_DUMPFILE() || DISKDUMP_DUMPFILE()) { + if (QEMU_MEM_DUMP_NO_VMCOREINFO()) { + if (KDUMP_DUMPFILE() && kdump_kaslr_check()) { + kt->flags2 |= KASLR_CHECK; + } + } else if (KDUMP_DUMPFILE() || DISKDUMP_DUMPFILE()) { if ((string = pc->read_vmcoreinfo("SYMBOL(_stext)"))) { kt->vmcoreinfo._stext_SYMBOL = htol(string, RETURN_ON_ERROR, NULL); @@ -640,7 +644,7 @@ derive_kaslr_offset(bfd *abfd, int dynamic, bfd_byte *start, bfd_byte *end, unsigned long relocate; ulong _stext_relocated; - if (SADUMP_DUMPFILE()) { + if (SADUMP_DUMPFILE() || QEMU_MEM_DUMP_NO_VMCOREINFO()) { ulong kaslr_offset = 0; ulong phys_base = 0; @@ -651,8 +655,12 @@ derive_kaslr_offset(bfd *abfd, int dynamic, bfd_byte *start, bfd_byte *end, kt->flags |= RELOC_SET; } - if (phys_base) - sadump_set_phys_base(phys_base); + if (phys_base) { + if (SADUMP_DUMPFILE()) + sadump_set_phys_base(phys_base); + else if (KDUMP_DUMPFILE()) + kdump_set_phys_base(phys_base); + } return; } @@ -3071,7 +3079,7 @@ dump_symbol_table(void) else fprintf(fp, "\n"); - if (SADUMP_DUMPFILE()) { + if (SADUMP_DUMPFILE() || QEMU_MEM_DUMP_NO_VMCOREINFO()) { fprintf(fp, "divide_error_vmlinux: %lx\n", st->divide_error_vmlinux); fprintf(fp, " idt_table_vmlinux: %lx\n", st->idt_table_vmlinux); fprintf(fp, "saved_command_line_vmlinux: %lx\n", st->saved_command_line_vmlinux); @@ -12298,7 +12306,7 @@ numeric_forward(const void *P_x, const void *P_y) } } - if (SADUMP_DUMPFILE()) { + if (SADUMP_DUMPFILE() || QEMU_MEM_DUMP_NO_VMCOREINFO()) { /* Need for kaslr_offset and phys_base */ if (STREQ(x->name, "divide_error")) st->divide_error_vmlinux = valueof(x); diff --git a/x86_64.c b/x86_64.c index 0d5e150..f6f6c0e 100644 --- a/x86_64.c +++ b/x86_64.c @@ -202,7 +202,7 @@ x86_64_init(int when) machdep->machspec->kernel_image_size = dtol(string, QUIET, NULL); free(string); } - if (SADUMP_DUMPFILE()) + if (SADUMP_DUMPFILE() || QEMU_MEM_DUMP_NO_VMCOREINFO()) /* Need for calculation of kaslr_offset and phys_base */ machdep->kvtop = x86_64_kvtop; break; @@ -2220,7 +2220,8 @@ x86_64_kvtop(struct task_context *tc, ulong kvaddr, physaddr_t *paddr, int verbo ulong pte; physaddr_t physpage; - if (SADUMP_DUMPFILE() && !(machdep->flags & KSYMS_START)) { + if ((SADUMP_DUMPFILE() || QEMU_MEM_DUMP_NO_VMCOREINFO()) + && !(machdep->flags & KSYMS_START)) { /* * In the case of sadump, to calculate kaslr_offset and * phys_base, kvtop is called during symtab_init(). In this @@ -6631,6 +6632,18 @@ x86_64_calc_phys_base(void) * Get relocation value from whatever dumpfile format is being used. */ + if (QEMU_MEM_DUMP_NO_VMCOREINFO()) { + if (KDUMP_DUMPFILE() && kdump_phys_base(&phys_base)) + machdep->machspec->phys_base = phys_base; + + if (!x86_64_virt_phys_base()) + error(WARNING, + "cannot determine physical base address:" + " defaulting to %lx\n\n", + machdep->machspec->phys_base); + return; + } + if (DISKDUMP_DUMPFILE()) { if (diskdump_phys_base(&phys_base)) { machdep->machspec->phys_base = phys_base; -- 2.14.3

Hi Sergio, (and Takao and Daisuke) This patch to map_cpus_to_prstatus_kdump_cmprs(): @@ -153,8 +154,13 @@ resize_note_pointers: dd->num_qemu_notes * sizeof(void *))) == NULL) error(FATAL, "compressed kdump: cannot realloc QEMU note pointers\n"); + if ((dd->nt_qemucs_percpu = realloc(dd->nt_qemucs_percpu, + dd->num_qemu_notes * sizeof(void *))) == NULL) + error(FATAL, + "compressed kdump: cannot realloc QEMU note pointers\n"); } else free(dd->nt_qemu_percpu); + free(dd->nt_qemucs_percpu); } } is missing brackets around the else clause, resulting in: if (machine_type("X86_64") || machine_type("X86") || machine_type("ARM64")) { if ((dd->nt_prstatus_percpu = realloc(dd->nt_prstatus_percpu, dd->num_prstatus_notes * sizeof(void *))) == NULL) error(FATAL, "compressed kdump: cannot realloc NT_PRSTATUS note pointers\n"); if (dd->num_qemu_notes) { if ((dd->nt_qemu_percpu = realloc(dd->nt_qemu_percpu, dd->num_qemu_notes * sizeof(void *))) == NULL) error(FATAL, "compressed kdump: cannot realloc QEMU note pointers\n"); if ((dd->nt_qemucs_percpu = realloc(dd->nt_qemucs_percpu, dd->num_qemu_notes * sizeof(void *))) == NULL) error(FATAL, "compressed kdump: cannot realloc QEMU note pointers\n"); } else free(dd->nt_qemu_percpu); free(dd->nt_qemucs_percpu); } So as soon as the realloc(dd->nt_qemucs_percpu, ...) is done, it gets free()'d. So I'm not sure how your testing worked, but presumably, the freed data remained untouched at least long enough to get the job done during initialization. One minor nit -- in order to be able to search for functions in a file by entering "^function_name", I prefer that function names always be placed on their own line, with the return type or void on the line above. Other that, the patch looks OK. As I mentioned before, I will need ACK's from Takao Indou and Daisuke Hatayama. They can fix the bracket bug above themselves for their sadump testing, so it's probably not necessary to repost the patch. I've added d.hatayama(a)jp.fujitsu.com to the cc: list. Thanks, Dave ----- Original Message -----