tcp: call sk_wmem_schedule before sk_mem_charge in zerocopy path

sk_wmem_schedule makes sure that sk_forward_alloc has enough bytes for charging that is going to be done by sk_mem_charge. In the transmit zerocopy path, there is sk_mem_charge but there was no call to sk_wmem_schedule. This change adds that call. Without this call to sk_wmem_schedule, sk_forward_alloc can go negetive which is a bug because sk_forward_alloc is a per-socket space that has been forward charged so this can't be negative. Fixes: f214f91 ("tcp: enable MSG_ZEROCOPY") Signed-off-by: Talal Ahmad <[email protected]> Reviewed-by: Willem de Bruijn <[email protected]> Reviewed-by: Wei Wang <[email protected]> Reviewed-by: Soheil Hassas Yeganeh <[email protected]> Signed-off-by: Eric Dumazet <[email protected]> Signed-off-by: David S. Miller <[email protected]>
chewitt · Jul 9, 2021 · 358ed62 · 358ed62
1 parent 43b90bf
commit 358ed62
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
@@ -1375,6 +1375,9 @@ int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size)
 			}
 			pfrag->offset += copy;
 		} else {
+			if (!sk_wmem_schedule(sk, copy))
+				goto wait_for_space;
+
 			err = skb_zerocopy_iter_stream(sk, skb, msg, copy, uarg);
 			if (err == -EMSGSIZE || err == -EEXIST) {
 				tcp_mark_push(tp, skb);