Hi Lianbo, I have the patch tested, looks good to me, so ack.

Thanks, Tao Liu On Wed, Jun 5, 2024 at 6:06 PM Lianbo Jiang <lijiang(a)redhat.com&gt; wrote: > > In some kernel modules such as libie.ko, the mem[MOD_TEXT].size > may be zero, currently crash will only check its value to determine > if the module is valid, otherwise it fails to load kernel module with > the following warning and error: > > WARNING: invalid kernel module size: 0 > KERNEL: /lib/modules/6.10.0-rc1+/build/vmlinux > DUMPFILE: /proc/kcore > CPUS: 64 > DATE: Wed Jun 5 12:49:02 IDT 2024 > UPTIME: 5 days, 05:57:21 > LOAD AVERAGE: 0.28, 0.06, 0.02 > TASKS: 806 > NODENAME: xxxx > RELEASE: 6.10.0-rc1+ > VERSION: #1 SMP PREEMPT_DYNAMIC Fri May 31 04:56:59 IDT 2024 > MACHINE: x86_64 (2100 Mhz) > MEMORY: 1.6 GB > PID: 203686 > COMMAND: "crash" > TASK: ffff9f9bf66d0000 [THREAD_INFO: ffff9f9bf66d0000] > CPU: 52 > STATE: TASK_RUNNING (ACTIVE) > > crash> mod > mod: cannot access vmalloc'd module memory > crash> > > Lets count the module size to check if the module is valid, that will > avoid the current failure. > > Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt; > --- > kernel.c | 20 ++++++++++++++++---- > 1 file changed, 16 insertions(+), 4 deletions(-) > > diff --git a/kernel.c b/kernel.c > index 1728b70c1b5c..e0dc23b9b233 100644 > --- a/kernel.c > +++ b/kernel.c > @@ -3821,9 +3821,21 @@ module_init(void) > case KALLSYMS_V2: > if (THIS_KERNEL_VERSION >= LINUX(2,6,27)) { > numksyms = UINT(modbuf + OFFSET(module_num_symtab)); > - if (MODULE_MEMORY()) > - /* check mem[MOD_TEXT].size only */ > - size = UINT(modbuf + OFFSET(module_mem) + OFFSET(module_memory_size)); > + if (MODULE_MEMORY()) { > + /* > + * The mem[MOD_TEXT].size may be zero, lets count > + * the module size as below. > + */ > + int t; > + size = 0; > + for_each_mod_mem_type(t) { > + if (t == MOD_INIT_TEXT) > + break; > + size += UINT(modbuf + OFFSET(module_mem) + > + SIZE(module_memory) * t + > + OFFSET(module_memory_size)); > + } > + } > else > size = UINT(modbuf + MODULE_OFFSET2(module_core_size, rx)); > } else { > @@ -3926,7 +3938,7 @@ verify_modules(void) > > for (i = 0, found = FALSE; i < kt->mods_installed; i++) { > lm = &st->load_modules[i]; > - if (!kvtop(NULL, lm->mod_base, &paddr, 0)) { > + if (lm->mod_base && !kvtop(NULL, lm->mod_base, &paddr, 0)) { > irregularities++; > break; > } > -- > 2.45.1 > -- > Crash-utility mailing list -- devel(a)lists.crash-utility.osci.io > To unsubscribe send an email to devel-leave(a)lists.crash-utility.osci.io > https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/ > Contribution Guidelines: https://github.com/crash-utility/crash/wiki

Hi Lianbo, The patch looks good to me, tested OK, so ack.

Thanks, Tao Liu On Wed, Jun 5, 2024 at 6:05 PM Lianbo Jiang <lijiang(a)redhat.com&gt; wrote: > > Kernel commit 223b5e57d0d5 ("mm/execmem, arch: convert remaining > overrides of module_alloc to execmem") makes crash session loading > failure as below: > > # ./crash -s > crash: seek error: kernel virtual address: ffffffff826bb418 type: "page_offset_base" > > For X86 64 architecture, currently crash will search for symbol > "module_load_offset" to determine if the KASLR is enabled, and go > into the relevant code block. But the symbols "module_load_offset" > has been removed since Linux v6.10-rc1, which caused the current > failure. > > And this issue can occur with live debugging and core dump file > debugging. > > Let's check the symbol "kaslr_regions" instead of "module_load_offset" > to fix it. > > Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt; > --- > symbols.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/symbols.c b/symbols.c > index b7627a83587a..1cdf21d86d69 100644 > --- a/symbols.c > +++ b/symbols.c > @@ -619,9 +619,9 @@ strip_symbol_end(const char *name, char *buf) > * or in /proc/kallsyms on a live system. > * > * Setting KASLR_CHECK will trigger a search for "module_load_offset" > - * during the initial symbol sort operation, and if found, will > - * set (RELOC_AUTO|KASLR). On live systems, the search is done > - * here by checking /proc/kallsyms. > + * or "kaslr_regions" during the initial symbol sort operation, and > + * if found, will set (RELOC_AUTO|KASLR). On live systems, the search > + * is done here by checking /proc/kallsyms. > */ > static void > kaslr_init(void) > @@ -646,7 +646,8 @@ kaslr_init(void) > st->_stext_vmlinux = UNINITIALIZED; > > if (ACTIVE() && /* Linux 3.15 */ > - (symbol_value_from_proc_kallsyms("module_load_offset") != BADVAL)) { > + ((symbol_value_from_proc_kallsyms("kaslr_regions") != BADVAL) || > + (symbol_value_from_proc_kallsyms("module_load_offset") != BADVAL))) { > kt->flags2 |= (RELOC_AUTO|KASLR); > st->_stext_vmlinux = UNINITIALIZED; > } > @@ -14247,7 +14248,9 @@ numeric_forward(const void *P_x, const void *P_y) > st->_stext_vmlinux = valueof(y); > } > if (kt->flags2 & KASLR_CHECK) { > - if (STREQ(x->name, "module_load_offset") || > + if (STREQ(x->name, "kaslr_regions") || > + STREQ(y->name, "kaslr_regions") || > + STREQ(x->name, "module_load_offset") || > STREQ(y->name, "module_load_offset")) { > kt->flags2 &= ~KASLR_CHECK; > kt->flags2 |= (RELOC_AUTO|KASLR); > -- > 2.45.1 > -- > Crash-utility mailing list -- devel(a)lists.crash-utility.osci.io > To unsubscribe send an email to devel-leave(a)lists.crash-utility.osci.io > https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/ > Contribution Guidelines: https://github.com/crash-utility/crash/wiki