Date: Fri, 1 Nov 2024 18:01:27 +0800
From: Guanyou Chen <chenguanyou9338@gmail.com>
Subject: [Crash-utility] [PATCH] bugfix command "help -r" segv fault
To: Lianbo <lijiang@redhat.com>, Tao Liu <ltao@redhat.com>,
devel@lists.crash-utility.osci.io
Message-ID:
<CAHS3RMU3nuiqW4z=Qo9RoufADrUxcaLhyjnxwMCuGODB_+37yQ@mail.gmail.com>
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Hi Lianbo, Tao
When the ELF Note does not contain CPU registers,
attempting to retrieve online CPU registers will cause a crash.
After:
CPU 6:
help: registers not collected for cpu 6
...
Signed-off-by: Guanyou.Chen <chenguanyou@xiaomi.com>
---
netdump.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)
diff --git a/netdump.c b/netdump.c
index 8ea5159..435793b 100644
--- a/netdump.c
+++ b/netdump.c
@@ -2780,6 +2780,10 @@ display_regs_from_elf_notes(int cpu, FILE *ofp)
I copied the code block here:
display_regs_from_elf_notes(int cpu, FILE *ofp)
{
Elf32_Nhdr *note32;
Elf64_Nhdr *note64;
size_t len;
char *user_regs;
int c, skipped_count;
/*
* Kdump NT_PRSTATUS notes are only related to online cpus,
* so offline cpus should be skipped.
*/
if (pc->flags2 & QEMU_MEM_DUMP_ELF)
skipped_count = 0;
else {
for (c = skipped_count = 0; c < cpu; c++) {
if (check_offline_cpu(c))
skipped_count++;
}
}
if ((cpu - skipped_count) >= nd->num_prstatus_notes &&
!machine_type("MIPS")) {
error(INFO, "registers not collected for cpu %d\n", cpu);
return;
}
...
Could you please point out why the above check does not work?
BTW: I'm not sure if it can work for you, can you help to try this? Just a guess.
if (((cpu < 0 ) || (!dd->nt_prstatus_percpu[cpu])
|| (cpu - skipped_count) >= nd->num_prstatus_notes) &&
!machine_type("MIPS")) {
error(INFO, "registers not collected for cpu %d\n", cpu);
return;
}
Thanks
Lianbo
nd->nt_prstatus_percpu[cpu];
else
note64 = (Elf64_Nhdr *)nd->nt_prstatus;
+ if (!note64) {
+ error(INFO, "registers not collected for cpu %d\n", cpu);
+ return;
+ }
len = sizeof(Elf64_Nhdr);
len = roundup(len + note64->n_namesz, 4);
len = roundup(len + note64->n_descsz, 4);
@@ -2820,6 +2824,10 @@ display_regs_from_elf_notes(int cpu, FILE *ofp)
nd->nt_prstatus_percpu[cpu];
else
note32 = (Elf32_Nhdr *)nd->nt_prstatus;
+ if (!note32) {
+ error(INFO, "registers not collected for cpu %d\n", cpu);
+ return;
+ }
len = sizeof(Elf32_Nhdr);
len = roundup(len + note32->n_namesz, 4);
len = roundup(len + note32->n_descsz, 4);
@@ -2857,6 +2865,10 @@ display_regs_from_elf_notes(int cpu, FILE *ofp)
else
note64 = (Elf64_Nhdr *)nd->nt_prstatus;
+ if (!note64) {
+ error(INFO, "registers not collected for cpu %d\n", cpu);
+ return;
+ }
prs = (struct ppc64_elf_prstatus *)
((char *)note64 + sizeof(Elf64_Nhdr) + note64->n_namesz);
prs = (struct ppc64_elf_prstatus *)roundup((ulong)prs, 4);
@@ -2903,6 +2915,10 @@ display_regs_from_elf_notes(int cpu, FILE *ofp)
nd->nt_prstatus_percpu[cpu];
else
note64 = (Elf64_Nhdr *)nd->nt_prstatus;
+ if (!note64) {
+ error(INFO, "registers not collected for cpu %d\n", cpu);
+ return;
+ }
len = sizeof(Elf64_Nhdr);
len = roundup(len + note64->n_namesz, 4);
len = roundup(len + note64->n_descsz, 4);
--
2.34.1
Guanyou.
Thanks