Messages in this thread Patch in this message | | | Subject | Re: [PATCH] static_call: fix null-ptr-deref in static_call_del_module | From | "wanghai (M)" <> | Date | Mon, 11 Oct 2021 11:18:55 +0800 |
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在 2021/10/9 18:00, Peter Zijlstra 写道: > On Sat, Oct 09, 2021 at 03:44:28PM +0800, Wang Hai wrote: >> I got a NULL pointer dereference report when doing fault injection test: >> >> BUG: kernel NULL pointer dereference, address: 0000000000000009 >> ... >> RIP: 0010:static_call_del_module+0x7a/0x100 >> ... >> Call Trace: >> static_call_module_notify+0x1e1/0x200 >> notifier_call_chain_robust+0x6f/0xe0 >> blocking_notifier_call_chain_robust+0x4e/0x70 >> load_module+0x21f7/0x2b60 >> __do_sys_finit_module+0xb0/0xf0 >> ? __do_sys_finit_module+0xb0/0xf0 >> __x64_sys_finit_module+0x1a/0x20 >> do_syscall_64+0x34/0xb0 >> entry_SYSCALL_64_after_hwframe+0x44/0xae >> >> When loading a module, if it fails to allocate memory for static >> calls, it will delete the non-existent mods (mods == 1) in the >> static_call_module_notify()'s error path. >> >> static_call_module_notify >> static_call_add_module >> __static_call_init >> site_mod = kzalloc() // fault injection >> static_call_del_module // access non-existent mods >> >> This patch fixes the bug by skipping the operation when the key >> has no mods. >> >> Fixes: a945c8345ec0 ("static_call: Allow early init") >> Signed-off-by: Wang Hai <wanghai38@huawei.com> >> --- >> kernel/static_call.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/kernel/static_call.c b/kernel/static_call.c >> index 43ba0b1e0edb..c3f8ffc5a52f 100644 >> --- a/kernel/static_call.c >> +++ b/kernel/static_call.c >> @@ -400,7 +400,7 @@ static void static_call_del_module(struct module *mod) >> >> for (site = start; site < stop; site++) { >> key = static_call_key(site); >> - if (key == prev_key) >> + if (key == prev_key || !static_call_key_has_mods(key)) >> continue; >> >> prev_key = key; > Should you not update prev_key in that case? Also have you looked at > jump_label_del_module() which is very similar in construction? > . Thanks for your guidance, as with jump_label_del_module(), the prev_key needs to be updated, can it be fixed like this?
--- a/kernel/static_call.c +++ b/kernel/static_call.c @@ -404,9 +404,9 @@ static void static_call_del_module(struct module *mod) continue;
prev_key = key; + site_mod = static_call_key_next(key);
- for (prev = &key->mods, site_mod = key->mods; - site_mod && site_mod->mod != mod; + for (prev = &key->mods; site_mod && site_mod->mod != mod; prev = &site_mod->next, site_mod = site_mod->next) ;
-- Wang Hai
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