modules: Fix module_bug_list list corruption race
With all the recent module loading cleanups, we've minimized the code
that sits under module_mutex, fixing various deadlocks and making it
possible to do most of the module loading in parallel.
However, that whole conversion totally missed the rather obscure code
that adds a new module to the list for BUG() handling. That code was
doubly obscure because (a) the code itself lives in lib/bugs.c (for
dubious reasons) and (b) it gets called from the architecture-specific
"module_finalize()" rather than from generic code.
Calling it from arch-specific code makes no sense what-so-ever to begin
with, and is now actively wrong since that code isn't protected by the
module loading lock any more.
So this commit moves the "module_bug_{finalize,cleanup}()" calls away
from the arch-specific code, and into the generic code - and in the
process protects it with the module_mutex so that the list operations
are now safe.
Future fixups:
- move the module list handling code into kernel/module.c where it
belongs.
- get rid of 'module_bug_list' and just use the regular list of modules
(called 'modules' - imagine that) that we already create and maintain
for other reasons.
Reported-and-tested-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Adrian Bunk <bunk@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/avr32/kernel/module.c b/arch/avr32/kernel/module.c
index 98f94d0..a727f54 100644
--- a/arch/avr32/kernel/module.c
+++ b/arch/avr32/kernel/module.c
@@ -314,10 +314,9 @@
vfree(module->arch.syminfo);
module->arch.syminfo = NULL;
- return module_bug_finalize(hdr, sechdrs, module);
+ return 0;
}
void module_arch_cleanup(struct module *module)
{
- module_bug_cleanup(module);
}
diff --git a/arch/h8300/kernel/module.c b/arch/h8300/kernel/module.c
index 0865e29..db4953d 100644
--- a/arch/h8300/kernel/module.c
+++ b/arch/h8300/kernel/module.c
@@ -112,10 +112,9 @@
const Elf_Shdr *sechdrs,
struct module *me)
{
- return module_bug_finalize(hdr, sechdrs, me);
+ return 0;
}
void module_arch_cleanup(struct module *mod)
{
- module_bug_cleanup(mod);
}
diff --git a/arch/mn10300/kernel/module.c b/arch/mn10300/kernel/module.c
index 6aea7fd..196a111 100644
--- a/arch/mn10300/kernel/module.c
+++ b/arch/mn10300/kernel/module.c
@@ -206,7 +206,7 @@
const Elf_Shdr *sechdrs,
struct module *me)
{
- return module_bug_finalize(hdr, sechdrs, me);
+ return 0;
}
/*
@@ -214,5 +214,4 @@
*/
void module_arch_cleanup(struct module *mod)
{
- module_bug_cleanup(mod);
}
diff --git a/arch/parisc/kernel/module.c b/arch/parisc/kernel/module.c
index 159a2b8..6e81bb5 100644
--- a/arch/parisc/kernel/module.c
+++ b/arch/parisc/kernel/module.c
@@ -941,11 +941,10 @@
nsyms = newptr - (Elf_Sym *)symhdr->sh_addr;
DEBUGP("NEW num_symtab %lu\n", nsyms);
symhdr->sh_size = nsyms * sizeof(Elf_Sym);
- return module_bug_finalize(hdr, sechdrs, me);
+ return 0;
}
void module_arch_cleanup(struct module *mod)
{
deregister_unwind_table(mod);
- module_bug_cleanup(mod);
}
diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
index 477c663..4ef93ae 100644
--- a/arch/powerpc/kernel/module.c
+++ b/arch/powerpc/kernel/module.c
@@ -65,10 +65,6 @@
const Elf_Shdr *sect;
int err;
- err = module_bug_finalize(hdr, sechdrs, me);
- if (err)
- return err;
-
/* Apply feature fixups */
sect = find_section(hdr, sechdrs, "__ftr_fixup");
if (sect != NULL)
@@ -101,5 +97,4 @@
void module_arch_cleanup(struct module *mod)
{
- module_bug_cleanup(mod);
}
diff --git a/arch/s390/kernel/module.c b/arch/s390/kernel/module.c
index 22cfd63..f7167ee 100644
--- a/arch/s390/kernel/module.c
+++ b/arch/s390/kernel/module.c
@@ -407,10 +407,9 @@
{
vfree(me->arch.syminfo);
me->arch.syminfo = NULL;
- return module_bug_finalize(hdr, sechdrs, me);
+ return 0;
}
void module_arch_cleanup(struct module *mod)
{
- module_bug_cleanup(mod);
}
diff --git a/arch/sh/kernel/module.c b/arch/sh/kernel/module.c
index 43adddf..ae0be69 100644
--- a/arch/sh/kernel/module.c
+++ b/arch/sh/kernel/module.c
@@ -149,13 +149,11 @@
int ret = 0;
ret |= module_dwarf_finalize(hdr, sechdrs, me);
- ret |= module_bug_finalize(hdr, sechdrs, me);
return ret;
}
void module_arch_cleanup(struct module *mod)
{
- module_bug_cleanup(mod);
module_dwarf_cleanup(mod);
}
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index e0bc186..1c355c5 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -239,11 +239,10 @@
apply_paravirt(pseg, pseg + para->sh_size);
}
- return module_bug_finalize(hdr, sechdrs, me);
+ return 0;
}
void module_arch_cleanup(struct module *mod)
{
alternatives_smp_module_del(mod);
- module_bug_cleanup(mod);
}
diff --git a/include/linux/module.h b/include/linux/module.h
index 8a6b9fd..aace066 100644
--- a/include/linux/module.h
+++ b/include/linux/module.h
@@ -686,17 +686,16 @@
#ifdef CONFIG_GENERIC_BUG
-int module_bug_finalize(const Elf_Ehdr *, const Elf_Shdr *,
+void module_bug_finalize(const Elf_Ehdr *, const Elf_Shdr *,
struct module *);
void module_bug_cleanup(struct module *);
#else /* !CONFIG_GENERIC_BUG */
-static inline int module_bug_finalize(const Elf_Ehdr *hdr,
+static inline void module_bug_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *mod)
{
- return 0;
}
static inline void module_bug_cleanup(struct module *mod) {}
#endif /* CONFIG_GENERIC_BUG */
diff --git a/kernel/module.c b/kernel/module.c
index d0b5f8d..ccd6419 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1537,6 +1537,7 @@
{
struct module *mod = _mod;
list_del(&mod->list);
+ module_bug_cleanup(mod);
return 0;
}
@@ -2625,6 +2626,7 @@
if (err < 0)
goto ddebug;
+ module_bug_finalize(info.hdr, info.sechdrs, mod);
list_add_rcu(&mod->list, &modules);
mutex_unlock(&module_mutex);
@@ -2650,6 +2652,8 @@
mutex_lock(&module_mutex);
/* Unlink carefully: kallsyms could be walking list. */
list_del_rcu(&mod->list);
+ module_bug_cleanup(mod);
+
ddebug:
if (!mod->taints)
dynamic_debug_remove(info.debug);
diff --git a/lib/bug.c b/lib/bug.c
index 7cdfad8..1955209 100644
--- a/lib/bug.c
+++ b/lib/bug.c
@@ -72,8 +72,8 @@
return NULL;
}
-int module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
- struct module *mod)
+void module_bug_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
+ struct module *mod)
{
char *secstrings;
unsigned int i;
@@ -97,8 +97,6 @@
* could potentially lead to deadlock and thus be counter-productive.
*/
list_add(&mod->bug_list, &module_bug_list);
-
- return 0;
}
void module_bug_cleanup(struct module *mod)