Messages in this thread Patch in this message | | | From | Wang Hai <> | Subject | [PATCH] static_call: fix null-ptr-deref in static_call_del_module | Date | Sat, 9 Oct 2021 15:44:28 +0800 |
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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; -- 2.17.1
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