Re: [PATCH nf-next v2 1/2] netfilter: Fix potential null pointer dereference
From: Feng Gao <hidden>
Date: 2016-09-28 01:23:34
Also in:
netfilter-devel
Hi Aaraon, On Tue, Sep 27, 2016 at 9:38 PM, Aaron Conole [off-list ref] wrote:
It's possible for nf_hook_entry_head to return NULL if two nf_unregister_net_hook calls happen simultaneously with a single hook
The critical region of nf_unregister_net_hook is protected by &nf_hook_mutex. When it would be called simultaneously? Regards Feng
quoted hunk ↗ jump to hunk
entry in the list. This fix ensures that no null pointer dereference could occur when such a race happens. Signed-off-by: Aaron Conole <redacted> --- net/netfilter/core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)diff --git a/net/netfilter/core.c b/net/netfilter/core.c index 360c63d..e58e420 100644 --- a/net/netfilter/core.c +++ b/net/netfilter/core.c@@ -160,7 +160,7 @@ void nf_unregister_net_hook(struct net *net, const struct nf_hook_ops *reg) mutex_lock(&nf_hook_mutex); hooks_entry = nf_hook_entry_head(net, reg); - if (hooks_entry->orig_ops == reg) { + if (hooks_entry && hooks_entry->orig_ops == reg) { nf_set_hooks_head(net, reg, nf_entry_dereference(hooks_entry->next)); goto unlock; --2.7.4 -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html