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authorCong Wang <xiyou.wangcong@gmail.com>2020-02-12 22:53:52 -0800
committerPablo Neira Ayuso <pablo@netfilter.org>2020-02-26 23:25:07 +0100
commit99b79c3900d4627672c85d9f344b5b0f06bc2a4d (patch)
tree96bd29993af77183af6ccedc4df190ffc284c391 /net
parent0954df70fba743d8cdaa09ccf6ba8e4ad09628de (diff)
netfilter: xt_hashlimit: unregister proc file before releasing mutex
Before releasing the global mutex, we only unlink the hashtable from the hash list, its proc file is still not unregistered at this point. So syzbot could trigger a race condition where a parallel htable_create() could register the same file immediately after the mutex is released. Move htable_remove_proc_entry() back to mutex protection to fix this. And, fold htable_destroy() into htable_put() to make the code slightly easier to understand. Reported-and-tested-by: syzbot+d195fd3b9a364ddd6731@syzkaller.appspotmail.com Fixes: c4a3922d2d20 ("netfilter: xt_hashlimit: reduce hashlimit_mutex scope for htable_put()") Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/xt_hashlimit.c16
1 files changed, 6 insertions, 10 deletions
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index 7a2c4b8408c4..8c835ad63729 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -402,15 +402,6 @@ static void htable_remove_proc_entry(struct xt_hashlimit_htable *hinfo)
remove_proc_entry(hinfo->name, parent);
}
-static void htable_destroy(struct xt_hashlimit_htable *hinfo)
-{
- cancel_delayed_work_sync(&hinfo->gc_work);
- htable_remove_proc_entry(hinfo);
- htable_selective_cleanup(hinfo, true);
- kfree(hinfo->name);
- vfree(hinfo);
-}
-
static struct xt_hashlimit_htable *htable_find_get(struct net *net,
const char *name,
u_int8_t family)
@@ -432,8 +423,13 @@ static void htable_put(struct xt_hashlimit_htable *hinfo)
{
if (refcount_dec_and_mutex_lock(&hinfo->use, &hashlimit_mutex)) {
hlist_del(&hinfo->node);
+ htable_remove_proc_entry(hinfo);
mutex_unlock(&hashlimit_mutex);
- htable_destroy(hinfo);
+
+ cancel_delayed_work_sync(&hinfo->gc_work);
+ htable_selective_cleanup(hinfo, true);
+ kfree(hinfo->name);
+ vfree(hinfo);
}
}