[PATCH 4.19 51/55] crypto: af_alg - Use bh_lock_sock in sk_destruct

Greg Kroah-Hartman
2020-01-30T18:49:08Z

From: Herbert Xu <herbert@gondor.apana.org.au>

commit 37f96694cf73ba116993a9d2d99ad6a75fa7fdb0 upstream.

As af_alg_release_parent may be called from BH context (most notably
due to an async request that only completes after socket closure,
or as reported here because of an RCU-delayed sk_destruct call), we
must use bh_lock_sock instead of lock_sock.

Reported-by: syzbot+c2f1558d49e25cc36e5e@syzkaller.appspotmail.com
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Fixes: c840ac6af3f8 ("crypto: af_alg - Disallow bind/setkey/...")
Cc: <stable@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
crypto/af_alg.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -139,11 +139,13 @@ void af_alg_release_parent(struct sock *
sk = ask->parent;
ask = alg_sk(sk);

- lock_sock(sk);
+ local_bh_disable();
+ bh_lock_sock(sk);
ask->nokey_refcnt -= nokey;
if (!last)
last = !--ask->refcnt;
- release_sock(sk);
+ bh_unlock_sock(sk);
+ local_bh_enable();

if (last)
sock_put(sk);