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authorYuchung Cheng <ycheng@google.com>2017-05-11 03:01:27 +0300
committerDavid S. Miller <davem@davemloft.net>2017-05-12 04:35:20 +0300
commitb451e5d24ba6687c6f0e7319c727a709a1846c06 (patch)
tree6c608e72316408de39225799630de48ee6d0509c /net
parentf6ba8d33cfbb46df569972e64dbb5bb7e929bfd9 (diff)
downloadlinux-b451e5d24ba6687c6f0e7319c727a709a1846c06.tar.xz
tcp: avoid fragmenting peculiar skbs in SACK
This patch fixes a bug in splitting an SKB during SACK processing. Specifically if an skb contains multiple packets and is only partially sacked in the higher sequences, tcp_match_sack_to_skb() splits the skb and marks the second fragment as SACKed. The current code further attempts rounding up the first fragment to MSS boundaries. But it misses a boundary condition when the rounded-up fragment size (pkt_len) is exactly skb size. Spliting such an skb is pointless and causses a kernel warning and aborts the SACK processing. This patch universally checks such over-split before calling tcp_fragment to prevent these unnecessary warnings. Fixes: adb92db857ee ("tcp: Make SACK code to split only at mss boundaries") Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Soheil Hassas Yeganeh <soheil@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ipv4/tcp_input.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 5a3ad09e2786..06e2dbc2b4a2 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -1179,13 +1179,14 @@ static int tcp_match_skb_to_sack(struct sock *sk, struct sk_buff *skb,
*/
if (pkt_len > mss) {
unsigned int new_len = (pkt_len / mss) * mss;
- if (!in_sack && new_len < pkt_len) {
+ if (!in_sack && new_len < pkt_len)
new_len += mss;
- if (new_len >= skb->len)
- return 0;
- }
pkt_len = new_len;
}
+
+ if (pkt_len >= skb->len && !in_sack)
+ return 0;
+
err = tcp_fragment(sk, skb, pkt_len, mss, GFP_ATOMIC);
if (err < 0)
return err;