crypto: chtls - use after free in chtls_pt_recvmsg()

Dan Carpenter · herbertx · commit f70b359b3830 · 2018-06-15T23:06:45.000+08:00
We call chtls_free_skb() but then we dereference it on the next lines. Also "skb" can't be NULL, we just dereferenced it on the line before. I have moved the free down a couple lines to fix this issue. Fixes: 17a7d24 ("crypto: chtls - generic handling of data and hdr") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/drivers/crypto/chelsio/chtls/chtls_io.c b/drivers/crypto/chelsio/chtls/chtls_io.c
@@ -1548,15 +1548,14 @@ static int chtls_pt_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
 			tp->urg_data = 0;
 
 		if ((avail + offset) >= skb->len) {
-			if (likely(skb))
-				chtls_free_skb(sk, skb);
-			buffers_freed++;
 			if (ULP_SKB_CB(skb)->flags & ULPCB_FLAG_TLS_HDR) {
 				tp->copied_seq += skb->len;
 				hws->rcvpld = skb->hdr_len;
 			} else {
 				tp->copied_seq += hws->rcvpld;
 			}
+			chtls_free_skb(sk, skb);
+			buffers_freed++;
 			hws->copied_seq = 0;
 			if (copied >= target &&
 			    !skb_peek(&sk->sk_receive_queue))
