netdev - [PATCH net 1/8] crypto: af_alg - fix possible uninit-value in alg

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Date:   Sat,  7 Apr 2018 13:42:36 -0700
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        Stephan Mueller <smueller@...onox.de>,
        Herbert Xu <herbert@...dor.apana.org.au>
Subject: [PATCH net 1/8] crypto: af_alg - fix possible uninit-value in alg_bind()

syzbot reported :

BUG: KMSAN: uninit-value in alg_bind+0xe3/0xd90 crypto/af_alg.c:162

We need to check addr_len before dereferencing sa (or uaddr)

Fixes: bb30b8848c85 ("crypto: af_alg - whitelist mask and type")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: syzbot <syzkaller@...glegroups.com>
Cc: Stephan Mueller <smueller@...onox.de>
Cc: Herbert Xu <herbert@...dor.apana.org.au>
---
 crypto/af_alg.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index c49766b03165ce095d218b09f0e22e7765e05388..7846c0c20cfec1998674e18e0a516a89caea509f 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -158,16 +158,16 @@ static int alg_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 	void *private;
 	int err;
 
-	/* If caller uses non-allowed flag, return error. */
-	if ((sa->salg_feat & ~allowed) || (sa->salg_mask & ~allowed))
-		return -EINVAL;
-
 	if (sock->state == SS_CONNECTED)
 		return -EINVAL;
 
 	if (addr_len < sizeof(*sa))
 		return -EINVAL;
 
+	/* If caller uses non-allowed flag, return error. */
+	if ((sa->salg_feat & ~allowed) || (sa->salg_mask & ~allowed))
+		return -EINVAL;
+
 	sa->salg_type[sizeof(sa->salg_type) - 1] = 0;
 	sa->salg_name[sizeof(sa->salg_name) + addr_len - sizeof(*sa) - 1] = 0;
 
-- 
2.17.0.484.g0c8726318c-goog