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| author | Eric Dumazet <edumazet@google.com> | 2013-10-15 22:54:30 +0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-11-04 16:23:40 +0400 |
| commit | 11db1e4cee071defc371d0fc7f1740024fbe5b06 (patch) | |
| tree | 3f31e7f8abf5be8eee3c2bd2de3306d1b41c233a /include | |
| parent | 3cebd7931a6f3007c3eb53942934772cc3b6ee08 (diff) | |
| download | linux-11db1e4cee071defc371d0fc7f1740024fbe5b06.tar.xz | |
tcp: must unclone packets before mangling them
[ Upstream commit c52e2421f7368fd36cbe330d2cf41b10452e39a9 ]
TCP stack should make sure it owns skbs before mangling them.
We had various crashes using bnx2x, and it turned out gso_size
was cleared right before bnx2x driver was populating TC descriptor
of the _previous_ packet send. TCP stack can sometime retransmit
packets that are still in Qdisc.
Of course we could make bnx2x driver more robust (using
ACCESS_ONCE(shinfo->gso_size) for example), but the bug is TCP stack.
We have identified two points where skb_unclone() was needed.
This patch adds a WARN_ON_ONCE() to warn us if we missed another
fix of this kind.
Kudos to Neal for finding the root cause of this bug. Its visible
using small MSS.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/skbuff.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index dc4d49a0c07d..daabf24655af 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -760,6 +760,16 @@ static inline int skb_cloned(const struct sk_buff *skb) (atomic_read(&skb_shinfo(skb)->dataref) & SKB_DATAREF_MASK) != 1; } +static inline int skb_unclone(struct sk_buff *skb, gfp_t pri) +{ + might_sleep_if(pri & __GFP_WAIT); + + if (skb_cloned(skb)) + return pskb_expand_head(skb, 0, 0, pri); + + return 0; +} + /** * skb_header_cloned - is the header a clone * @skb: buffer to check |