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authorEric Dumazet <edumazet@google.com>2017-01-27 07:11:27 -0800
committerDavid S. Miller <davem@davemloft.net>2017-01-27 12:03:29 -0500
commit158f323b9868b59967ad96957c4ca388161be321 (patch)
tree507829772e7f0849038baf503f85fe788b0e4340 /net/netlink
parentb41fd8fdef5ad4a1dbd2a159714bd4358bb49625 (diff)
net: adjust skb->truesize in pskb_expand_head()
Slava Shwartsman reported a warning in skb_try_coalesce(), when we detect skb->truesize is completely wrong. In his case, issue came from IPv6 reassembly coping with malicious datagrams, that forced various pskb_may_pull() to reallocate a bigger skb->head than the one allocated by NIC driver before entering GRO layer. Current code does not change skb->truesize, leaving this burden to callers if they care enough. Blindly changing skb->truesize in pskb_expand_head() is not easy, as some producers might track skb->truesize, for example in xmit path for back pressure feedback (sk->sk_wmem_alloc) We can detect the cases where it should be safe to change skb->truesize : 1) skb is not attached to a socket. 2) If it is attached to a socket, destructor is sock_edemux() My audit gave only two callers doing their own skb->truesize manipulation. I had to remove skb parameter in sock_edemux macro when CONFIG_INET is not set to avoid a compile error. Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Slava Shwartsman <slavash@mellanox.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/netlink')
-rw-r--r--net/netlink/af_netlink.c8
1 files changed, 3 insertions, 5 deletions
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index edcc1e19ad53..7b73c7c161a9 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1210,11 +1210,9 @@ static struct sk_buff *netlink_trim(struct sk_buff *skb, gfp_t allocation)
skb = nskb;
}
- if (!pskb_expand_head(skb, 0, -delta,
- (allocation & ~__GFP_DIRECT_RECLAIM) |
- __GFP_NOWARN | __GFP_NORETRY))
- skb->truesize -= delta;
-
+ pskb_expand_head(skb, 0, -delta,
+ (allocation & ~__GFP_DIRECT_RECLAIM) |
+ __GFP_NOWARN | __GFP_NORETRY);
return skb;
}