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tcp: fix skb_availroom()

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Chrome OS team reported a crash on a Pixel ChromeBook in TCP stack :

https://code.google.com/p/chromium/issues/detail?id=182056

commit a21d45726a (tcp: avoid order-1 allocations on wifi and tx
path) did a poor choice adding an 'avail_size' field to skb, while
what we really needed was a 'reserved_tailroom' one.

It would have avoided commit 22b4a4f22d (tcp: fix retransmit of
partially acked frames) and this commit.

Crash occurs because skb_split() is not aware of the 'avail_size'
management (and should not be aware)

Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: Mukesh Agrawal <quiche@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2013-03-14 05:40:32 +00:00
committed by David S. Miller
parent b701f16dd4
commit 16fad69cfe
3 changed files with 6 additions and 4 deletions
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7
include/linux/skbuff.h
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@@ -500,7 +500,7 @@ struct sk_buff {
union {
__u32 mark;
__u32 dropcount;
__u32 avail_size;
__u32 reserved_tailroom;
};
sk_buff_data_t inner_transport_header;
@@ -1447,7 +1447,10 @@ static inline int skb_tailroom(const struct sk_buff *skb)
*/
static inline int skb_availroom(const struct sk_buff *skb)
{
return skb_is_nonlinear(skb) ? 0 : skb->avail_size - skb->len;
if (skb_is_nonlinear(skb))
return 0;
return skb->end - skb->tail - skb->reserved_tailroom;
}
/**