chelsio/chtls: prevent potential integer overflow on 32bit

The "gl->tot_len" variable is controlled by the user.  It comes from
process_responses().  On 32bit systems, the "gl->tot_len +
sizeof(struct cpl_pass_accept_req) + sizeof(struct rss_header)" addition
could have an integer wrapping bug.  Use size_add() to prevent this.

Fixes: a089439 ("crypto: chtls - Register chtls with net tls")
Cc: [email protected]
Signed-off-by: Dan Carpenter <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: Dan Carpenter

drivers/net/ethernet/chelsio/inline_crypto/chtls/chtls_main.c

@@ -346,8 +346,9 @@ static struct sk_buff *copy_gl_to_skb_pkt(const struct pkt_gl *gl,
 	 * driver. Once driver synthesizes cpl_pass_accept_req the skb will go
 	 * through the regular cpl_pass_accept_req processing in TOM.
 	 */
-	skb = alloc_skb(gl->tot_len + sizeof(struct cpl_pass_accept_req)
-			- pktshift, GFP_ATOMIC);
+	skb = alloc_skb(size_add(gl->tot_len,
+				 sizeof(struct cpl_pass_accept_req)) -
+			pktshift, GFP_ATOMIC);
 	if (unlikely(!skb))
 		return NULL;
 	__skb_put(skb, gl->tot_len + sizeof(struct cpl_pass_accept_req)