diff options
| author | Eric Dumazet <edumazet@google.com> | 2013-10-15 11:54:30 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-11-04 04:23:40 -0800 |
| commit | 11db1e4cee071defc371d0fc7f1740024fbe5b06 (patch) | |
| tree | 3f31e7f8abf5be8eee3c2bd2de3306d1b41c233a | |
| parent | 3cebd7931a6f3007c3eb53942934772cc3b6ee08 (diff) | |
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>
| -rw-r--r-- | include/linux/skbuff.h | 10 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 9 |
2 files changed, 16 insertions, 3 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 diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 12999a3aaf95..987f5cc706b4 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -933,6 +933,9 @@ static void tcp_queue_skb(struct sock *sk, struct sk_buff *skb) static void tcp_set_skb_tso_segs(const struct sock *sk, struct sk_buff *skb, unsigned int mss_now) { + /* Make sure we own this skb before messing gso_size/gso_segs */ + WARN_ON_ONCE(skb_cloned(skb)); + if (skb->len <= mss_now || !sk_can_gso(sk) || skb->ip_summed == CHECKSUM_NONE) { /* Avoid the costly divide in the normal @@ -1014,9 +1017,7 @@ int tcp_fragment(struct sock *sk, struct sk_buff *skb, u32 len, if (nsize < 0) nsize = 0; - if (skb_cloned(skb) && - skb_is_nonlinear(skb) && - pskb_expand_head(skb, 0, 0, GFP_ATOMIC)) + if (skb_unclone(skb, GFP_ATOMIC)) return -ENOMEM; /* Get a new skb... force flag on. */ @@ -2129,6 +2130,8 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb) int oldpcount = tcp_skb_pcount(skb); if (unlikely(oldpcount > 1)) { + if (skb_unclone(skb, GFP_ATOMIC)) + return -ENOMEM; tcp_init_tso_segs(sk, skb, cur_mss); tcp_adjust_pcount(sk, skb, oldpcount - tcp_skb_pcount(skb)); } |