crypto: algif_hash - Remove bogus SGL free on zero-length error path

When a zero-length message is hashed by algif_hash, and an error
is triggered, it tries to free an SG list that was never allocated
in the first place.  Fix this by not freeing the SG list on the
zero-length error path.

Reported-by: Shigeru Yoshida <syoshida@redhat.com>
Reported-by: xingwei lee <xrivendell7@gmail.com>
Fixes: b6d972f68983 ("crypto: af_alg/hash: Fix recvmsg() after sendmsg(MSG_MORE)")
Cc: <stable@vger.kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Reported-by: syzbot+3266db0c26d1fbbe3abb@syzkaller.appspotmail.com
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
index 82c44d4899b9676d4d43c2f2af7fd9f95758b894..e24c829d7a0154f0ff016152e6913bff105cd93f 100644 (file)
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -91,13 +91,13 @@ static int hash_sendmsg(struct socket *sock, struct msghdr *msg,
                if (!(msg->msg_flags & MSG_MORE)) {
                        err = hash_alloc_result(sk, ctx);
                        if (err)
-                               goto unlock_free;
+                               goto unlock_free_result;
                        ahash_request_set_crypt(&ctx->req, NULL,
                                                ctx->result, 0);
                        err = crypto_wait_req(crypto_ahash_final(&ctx->req),
                                              &ctx->wait);
                        if (err)
-                               goto unlock_free;
+                               goto unlock_free_result;
                }
                goto done_more;
        }
@@ -170,6 +170,7 @@ unlock:
 
 unlock_free:
        af_alg_free_sg(&ctx->sgl);
+unlock_free_result:
        hash_free_result(sk, ctx);
        ctx->more = false;
        goto unlock;