path: root/net/packet/af_packet.c
diff options
authorWillem de Bruijn <willemb@google.com>2018-05-24 18:10:30 -0400
committerDavid S. Miller <davem@davemloft.net>2018-05-24 21:55:20 -0400
commit9aad13b087ab0a588cd68259de618f100053360e (patch)
tree3b8aa031c4bbfe2fe07021e9aa7de0805c63e926 /net/packet/af_packet.c
parentd546b67cda015fb92bfee93d5dc0ceadb91deaee (diff)
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/af_packet.c')
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 */