[PATCH net] net: tcp: fix crashes trying to free half-baked MTU probes

[Jakub Kicinski <kuba@kernel.org>]

tcp_stream_alloc_skb() initializes the skb to use tcp_tsorted_anchor
which is a union with the destructor. We need to clean that
TCP-iness up before freeing.

Fixes: 736013292e3c ("tcp: let tcp_mtu_probe() build headless packets")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
Thanks to Chris Mason for debug help and Omar Sandoval for
amazing drgn skills and analysis which make all bugs look
obvious :)
---
CC: dsahern@kernel.org
CC: clm@fb.com
CC: osandov@osandov.com
---
 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 f207712eece1..d5961a82a9e8 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2449,6 +2449,7 @@ static int tcp_mtu_probe(struct sock *sk)
 
 	/* build the payload, and be prepared to abort if this fails. */
 	if (tcp_clone_payload(sk, nskb, probe_size)) {
+		tcp_skb_tsorted_anchor_cleanup(nskb);
 		consume_skb(nskb);
 		return -1;
 	}
-- 
2.41.0