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| author | Tom Parkin <tparkin@katalix.com> | 2024-02-20 12:21:56 +0000 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2024-02-22 10:42:17 +0100 |
| commit | 359e54a93ab43d32ee1bff3c2f9f10cb9f6b6e79 (patch) | |
| tree | 6c268c27eb84c99869ee93ebb0715ec815c0b968 /net/l2tp | |
| parent | 9ff27943060c0282ca14e40f05c2b907edc85a42 (diff) | |
| download | lwn-359e54a93ab43d32ee1bff3c2f9f10cb9f6b6e79.tar.gz lwn-359e54a93ab43d32ee1bff3c2f9f10cb9f6b6e79.zip | |
l2tp: pass correct message length to ip6_append_data
l2tp_ip6_sendmsg needs to avoid accounting for the transport header
twice when splicing more data into an already partially-occupied skbuff.
To manage this, we check whether the skbuff contains data using
skb_queue_empty when deciding how much data to append using
ip6_append_data.
However, the code which performed the calculation was incorrect:
ulen = len + skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0;
...due to C operator precedence, this ends up setting ulen to
transhdrlen for messages with a non-zero length, which results in
corrupted packets on the wire.
Add parentheses to correct the calculation in line with the original
intent.
Fixes: 9d4c75800f61 ("ipv4, ipv6: Fix handling of transhdrlen in __ip{,6}_append_data()")
Cc: David Howells <dhowells@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20240220122156.43131-1-tparkin@katalix.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net/l2tp')
| -rw-r--r-- | net/l2tp/l2tp_ip6.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c index dd3153966173..7bf14cf9ffaa 100644 --- a/net/l2tp/l2tp_ip6.c +++ b/net/l2tp/l2tp_ip6.c @@ -627,7 +627,7 @@ static int l2tp_ip6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) back_from_confirm: lock_sock(sk); - ulen = len + skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0; + ulen = len + (skb_queue_empty(&sk->sk_write_queue) ? transhdrlen : 0); err = ip6_append_data(sk, ip_generic_getfrag, msg, ulen, transhdrlen, &ipc6, &fl6, (struct rt6_info *)dst, |