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| author | Masami Hiramatsu <mhiramat@redhat.com> | 2009-03-16 18:13:36 -0400 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2009-03-18 09:31:21 +1030 |
| commit | 6e2b75740bed35df98b8113300579e13ed2ce848 (patch) | |
| tree | 225f75f803450c728d546c755f7398b102f8cf3d /kernel | |
| parent | ee568b25ee9e160b32d1aef73d8b2ee9c05d34db (diff) | |
| download | lwn-6e2b75740bed35df98b8113300579e13ed2ce848.tar.gz lwn-6e2b75740bed35df98b8113300579e13ed2ce848.zip | |
module: fix refptr allocation and release order
Impact: fix ref-after-free crash on failed module load
Fix refptr bug: Change refptr allocation and release order not to access a module
data structure pointed by 'mod' after freeing mod->module_core.
This bug will cause kernel panic(e.g. failed to find undefined symbols).
This bug was reported on systemtap bugzilla.
http://sources.redhat.com/bugzilla/show_bug.cgi?id=9927
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/module.c | 26 |
1 files changed, 14 insertions, 12 deletions
diff --git a/kernel/module.c b/kernel/module.c index ba22484a987e..1196f5d11700 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2015,14 +2015,6 @@ static noinline struct module *load_module(void __user *umod, if (err < 0) goto free_mod; -#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) - mod->refptr = percpu_modalloc(sizeof(local_t), __alignof__(local_t), - mod->name); - if (!mod->refptr) { - err = -ENOMEM; - goto free_mod; - } -#endif if (pcpuindex) { /* We have a special allocation for this section. */ percpu = percpu_modalloc(sechdrs[pcpuindex].sh_size, @@ -2030,7 +2022,7 @@ static noinline struct module *load_module(void __user *umod, mod->name); if (!percpu) { err = -ENOMEM; - goto free_percpu; + goto free_mod; } sechdrs[pcpuindex].sh_flags &= ~(unsigned long)SHF_ALLOC; mod->percpu = percpu; @@ -2082,6 +2074,14 @@ static noinline struct module *load_module(void __user *umod, /* Module has been moved. */ mod = (void *)sechdrs[modindex].sh_addr; +#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) + mod->refptr = percpu_modalloc(sizeof(local_t), __alignof__(local_t), + mod->name); + if (!mod->refptr) { + err = -ENOMEM; + goto free_init; + } +#endif /* Now we've moved module, initialize linked lists, etc. */ module_unload_init(mod); @@ -2288,15 +2288,17 @@ static noinline struct module *load_module(void __user *umod, ftrace_release(mod->module_core, mod->core_size); free_unload: module_unload_free(mod); + free_init: +#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) + percpu_modfree(mod->refptr); +#endif module_free(mod, mod->module_init); free_core: module_free(mod, mod->module_core); + /* mod will be freed with core. Don't access it beyond this line! */ free_percpu: if (percpu) percpu_modfree(percpu); -#if defined(CONFIG_MODULE_UNLOAD) && defined(CONFIG_SMP) - percpu_modfree(mod->refptr); -#endif free_mod: kfree(args); free_hdr: |