From 22b4a4f22da4b39c6f7f679fd35f3d35c91bf851 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 18 Apr 2012 10:14:23 +0000 Subject: [PATCH] tcp: fix retransmit of partially acked frames Alexander Beregalov reported skb_over_panic errors and provided stack trace. I occurs commit a21d45726aca (tcp: avoid order-1 allocations on wifi and tx path) added a regression, when a retransmit is done after a partial ACK. tcp_retransmit_skb() tries to aggregate several frames if the first one has enough available room to hold the following ones payload. This is controlled by /proc/sys/net/ipv4/tcp_retrans_collapse tunable (default : enabled) Problem is we must make sure _pskb_trim_head() doesnt fool skb_availroom() when pulling some bytes from skb (this pull is done when receiver ACK part of the frame). Reported-by: Alexander Beregalov Cc: Marc MERLIN Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/tcp_output.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 376b2cfbb685..7ac6423117ad 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1096,6 +1096,7 @@ static void __pskb_trim_head(struct sk_buff *skb, int len) eat = min_t(int, len, skb_headlen(skb)); if (eat) { __skb_pull(skb, eat); + skb->avail_size -= eat; len -= eat; if (!len) return; -- 2.39.2