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| author | Willem de Bruijn <willemb@google.com> | 2018-05-24 18:10:30 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-05-24 21:55:20 -0400 |
| commit | 9aad13b087ab0a588cd68259de618f100053360e (patch) | |
| tree | 3b8aa031c4bbfe2fe07021e9aa7de0805c63e926 /net/packet | |
| parent | d546b67cda015fb92bfee93d5dc0ceadb91deaee (diff) | |
| download | linux-9aad13b087ab0a588cd68259de618f100053360e.tar.gz linux-9aad13b087ab0a588cd68259de618f100053360e.tar.bz2 linux-9aad13b087ab0a588cd68259de618f100053360e.zip | |
packet: fix reserve calculation
Commit b84bbaf7a6c8 ("packet: in packet_snd start writing at link
layer allocation") ensures that packet_snd always starts writing
the link layer header in reserved headroom allocated for this
purpose.
This is needed because packets may be shorter than hard_header_len,
in which case the space up to hard_header_len may be zeroed. But
that necessary padding is not accounted for in skb->len.
The fix, however, is buggy. It calls skb_push, which grows skb->len
when moving skb->data back. But in this case packet length should not
change.
Instead, call skb_reserve, which moves both skb->data and skb->tail
back, without changing length.
Fixes: b84bbaf7a6c8 ("packet: in packet_snd start writing at link layer allocation")
Reported-by: Tariq Toukan <tariqt@mellanox.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/packet')
| -rw-r--r-- | net/packet/af_packet.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index e9422fe45179..acb7b86574cd 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -2911,7 +2911,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len) if (unlikely(offset < 0)) goto out_free; } else if (reserve) { - skb_push(skb, reserve); + skb_reserve(skb, -reserve); } /* Returns -EFAULT on error */ |