From f6fccb0a0e59d6e34fab80f5684764d689f27ca7 Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Wed, 12 Feb 2020 22:53:52 -0800 Subject: [PATCH] netfilter: xt_hashlimit: unregister proc file before releasing mutex [ Upstream commit 99b79c3900d4627672c85d9f344b5b0f06bc2a4d ] 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 Signed-off-by: Pablo Neira Ayuso Signed-off-by: Sasha Levin --- net/netfilter/xt_hashlimit.c | 16 ++++++---------- 1 file 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); } }