crypto: af_alg - Initialize sg_num_bytes in error code path

The RX SGL in processing is already registered with the RX SGL tracking
list to support proper cleanup. The cleanup code path uses the
sg_num_bytes variable which must therefore be always initialized, even
in the error code path.

Signed-off-by: Stephan Mueller <[email protected]>
Reported-by: [email protected]
#syz test: https://github.com/google/kmsan.git master
CC: <[email protected]> #4.14
Fixes: e870456 ("crypto: algif_skcipher - overhaul memory management")
Fixes: d887c52 ("crypto: algif_aead - overhaul memory management")
Signed-off-by: Herbert Xu <[email protected]>

Author: smuellerDD

crypto/af_alg.c

@@ -1156,8 +1156,10 @@ int af_alg_get_rsgl(struct sock *sk, struct msghdr *msg, int flags,
 
 		/* make one iovec available as scatterlist */
 		err = af_alg_make_sg(&rsgl->sgl, &msg->msg_iter, seglen);
-		if (err < 0)
+		if (err < 0) {
+			rsgl->sg_num_bytes = 0;
 			return err;
+		}
 
 		/* chain the new scatterlist with previous one */
 		if (areq->last_rsgl)