netpoll: fix netpoll_send_udp() bugs
authorEric Dumazet <edumazet@google.com>
Tue, 12 Jun 2012 19:30:21 +0000 (19:30 +0000)
committerBen Hutchings <ben@decadent.org.uk>
Thu, 12 Jul 2012 03:32:15 +0000 (04:32 +0100)
commitb83d32ea5e66121fcf169ac1629836f87658fdcf
tree1075f566ebb9fce26dc1b790f1491360e50048ff
parentdad3f9c2bef47dd67cc930eea826af2814a7c568
netpoll: fix netpoll_send_udp() bugs

[ Upstream commit 954fba0274058d27c7c07b5ea07c41b3b7477894 ]

Bogdan Hamciuc diagnosed and fixed following bug in netpoll_send_udp() :

"skb->len += len;" instead of "skb_put(skb, len);"

Meaning that _if_ a network driver needs to call skb_realloc_headroom(),
only packet headers would be copied, leaving garbage in the payload.

However the skb_realloc_headroom() must be avoided as much as possible
since it requires memory and netpoll tries hard to work even if memory
is exhausted (using a pool of preallocated skbs)

It appears netpoll_send_udp() reserved 16 bytes for the ethernet header,
which happens to work for typicall drivers but not all.

Right thing is to use LL_RESERVED_SPACE(dev)
(And also add dev->needed_tailroom of tailroom)

This patch combines both fixes.

Many thanks to Bogdan for raising this issue.

Reported-by: Bogdan Hamciuc <bogdan.hamciuc@freescale.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Bogdan Hamciuc <bogdan.hamciuc@freescale.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Neil Horman <nhorman@tuxdriver.com>
Reviewed-by: Neil Horman <nhorman@tuxdriver.com>
Reviewed-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
net/core/netpoll.c