Messages in this thread Patch in this message | | | From | Jiri Slaby <> | Subject | [PATCH 3.12 19/83] tcp: Fix crash in TCP Fast Open | Date | Mon, 27 Apr 2015 23:31:50 +0200 |
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From: Ben Hutchings <ben@decadent.org.uk>
3.12-stable review patch. If anyone has any objections, please let me know.
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Commit 355a901e6cf1 ("tcp: make connect() mem charging friendly") changed tcp_send_syn_data() to perform an open-coded copy of the 'syn' skb rather than using skb_copy_expand().
The open-coded copy does not cover the skb_shared_info::gso_segs field, so in the new skb it is left set to 0. When this commit was backported into stable branches between 3.10.y and 3.16.7-ckty inclusive, it triggered the BUG() in tcp_transmit_skb().
Since Linux 3.18 the GSO segment count is kept in the tcp_skb_cb::tcp_gso_segs field and tcp_send_syn_data() does copy the tcp_skb_cb structure to the new skb, so mainline and newer stable branches are not affected.
Set skb_shared_info::gso_segs to the correct value of 1.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz> --- 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 e07ccba040be..56db79dbc633 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -2919,6 +2919,7 @@ static int tcp_send_syn_data(struct sock *sk, struct sk_buff *syn) goto fallback; syn_data->ip_summed = CHECKSUM_PARTIAL; memcpy(syn_data->cb, syn->cb, sizeof(syn->cb)); + skb_shinfo(syn_data)->gso_segs = 1; if (unlikely(memcpy_fromiovecend(skb_put(syn_data, space), fo->data->msg_iov, 0, space))) { kfree_skb(syn_data); -- 2.3.5
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