module: fix crash in get_ksymbol() when oopsing in module init
Andrew had the sole pleasure of tickling this bug in linux-next; when we set
up "info->strtab" it's pointing into the temporary copy of the module. For
most uses that is fine, but kallsyms keeps a pointer around during module
load (inside mod->strtab).
If we oops for some reason inside a module's init function, kallsyms will use
the mod->strtab pointer into the now-freed temporary module copy.
(Later oopses work fine: after init we overwrite mod->strtab to point to a
compacted core-only strtab).
Reported-by: Andrew "Grumpy" Morton <akpm@linux-foundation.org>
Signed-off-by: Rusty "Buggy" Russell <rusty@rustcorp.com.au>
Tested-by: Andrew "Happy" Morton <akpm@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
diff --git a/kernel/module.c b/kernel/module.c
index 79c4d6f..60cdd04 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2045,7 +2045,8 @@
mod->symtab = (void *)symsec->sh_addr;
mod->num_symtab = symsec->sh_size / sizeof(Elf_Sym);
- mod->strtab = info->strtab;
+ /* Make sure we get permanent strtab: don't use info->strtab. */
+ mod->strtab = (void *)info->sechdrs[info->index.str].sh_addr;
/* Set types up while we still have access to sections. */
for (i = 0; i < mod->num_symtab; i++)