4.4-stable review patch. If anyone has any objections, please let me know.
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From: Cong Wang xiyou.wangcong@gmail.com
commit 7dc68e98757a8eccf8ca7a53a29b896f1eef1f76 upstream.
rateest_hash is supposed to be protected by xt_rateest_mutex, and, as suggested by Eric, lookup and insert should be atomic, so we should acquire the xt_rateest_mutex once for both.
So introduce a non-locking helper for internal use and keep the locking one for external.
Reported-by: syzbot+5cb189720978275e4c75@syzkaller.appspotmail.com Fixes: 5859034d7eb8 ("[NETFILTER]: x_tables: add RATEEST target") Signed-off-by: Cong Wang xiyou.wangcong@gmail.com Reviewed-by: Florian Westphal fw@strlen.de Reviewed-by: Eric Dumazet edumazet@google.com Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/netfilter/xt_RATEEST.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-)
--- a/net/netfilter/xt_RATEEST.c +++ b/net/netfilter/xt_RATEEST.c @@ -40,23 +40,31 @@ static void xt_rateest_hash_insert(struc hlist_add_head(&est->list, &rateest_hash[h]); }
-struct xt_rateest *xt_rateest_lookup(const char *name) +static struct xt_rateest *__xt_rateest_lookup(const char *name) { struct xt_rateest *est; unsigned int h;
h = xt_rateest_hash(name); - mutex_lock(&xt_rateest_mutex); hlist_for_each_entry(est, &rateest_hash[h], list) { if (strcmp(est->name, name) == 0) { est->refcnt++; - mutex_unlock(&xt_rateest_mutex); return est; } } - mutex_unlock(&xt_rateest_mutex); + return NULL; } + +struct xt_rateest *xt_rateest_lookup(const char *name) +{ + struct xt_rateest *est; + + mutex_lock(&xt_rateest_mutex); + est = __xt_rateest_lookup(name); + mutex_unlock(&xt_rateest_mutex); + return est; +} EXPORT_SYMBOL_GPL(xt_rateest_lookup);
void xt_rateest_put(struct xt_rateest *est) @@ -104,8 +112,10 @@ static int xt_rateest_tg_checkentry(cons rnd_inited = true; }
- est = xt_rateest_lookup(info->name); + mutex_lock(&xt_rateest_mutex); + est = __xt_rateest_lookup(info->name); if (est) { + mutex_unlock(&xt_rateest_mutex); /* * If estimator parameters are specified, they must match the * existing estimator. @@ -143,11 +153,13 @@ static int xt_rateest_tg_checkentry(cons
info->est = est; xt_rateest_hash_insert(est); + mutex_unlock(&xt_rateest_mutex); return 0;
err2: kfree(est); err1: + mutex_unlock(&xt_rateest_mutex); return ret; }