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| author | Pablo Neira <pablo@netfilter.org> | 2013-06-28 03:04:23 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2013-06-27 22:44:16 -0700 |
| commit | 3a36515f729458c8efa0c124c7262d5843ad5c37 (patch) | |
| tree | 75924228bbebccdbbbbe1c8cca9b65d121843a0a /net/ipv4 | |
| parent | 5e6700b3bf98fe98d630bf9c939ad4c85ce95592 (diff) | |
| download | linux-3a36515f729458c8efa0c124c7262d5843ad5c37.tar.gz linux-3a36515f729458c8efa0c124c7262d5843ad5c37.tar.bz2 linux-3a36515f729458c8efa0c124c7262d5843ad5c37.zip | |
netlink: fix splat in skb_clone with large messages
Since (c05cdb1 netlink: allow large data transfers from user-space),
netlink splats if it invokes skb_clone on large netlink skbs since:
* skb_shared_info was not correctly initialized.
* skb->destructor is not set in the cloned skb.
This was spotted by trinity:
[ 894.990671] BUG: unable to handle kernel paging request at ffffc9000047b001
[ 894.991034] IP: [<ffffffff81a212c4>] skb_clone+0x24/0xc0
[...]
[ 894.991034] Call Trace:
[ 894.991034] [<ffffffff81ad299a>] nl_fib_input+0x6a/0x240
[ 894.991034] [<ffffffff81c3b7e6>] ? _raw_read_unlock+0x26/0x40
[ 894.991034] [<ffffffff81a5f189>] netlink_unicast+0x169/0x1e0
[ 894.991034] [<ffffffff81a601e1>] netlink_sendmsg+0x251/0x3d0
Fix it by:
1) introducing a new netlink_skb_clone function that is used in nl_fib_input,
that sets our special skb->destructor in the cloned skb. Moreover, handle
the release of the large cloned skb head area in the destructor path.
2) not allowing large skbuffs in the netlink broadcast path. I cannot find
any reasonable use of the large data transfer using netlink in that path,
moreover this helps to skip extra skb_clone handling.
I found two more netlink clients that are cloning the skbs, but they are
not in the sendmsg path. Therefore, the sole client cloning that I found
seems to be the fib frontend.
Thanks to Eric Dumazet for helping to address this issue.
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/fib_frontend.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c index 05a4888dede9..b3f627ac4ed8 100644 --- a/net/ipv4/fib_frontend.c +++ b/net/ipv4/fib_frontend.c @@ -961,7 +961,7 @@ static void nl_fib_input(struct sk_buff *skb) nlmsg_len(nlh) < sizeof(*frn)) return; - skb = skb_clone(skb, GFP_KERNEL); + skb = netlink_skb_clone(skb, GFP_KERNEL); if (skb == NULL) return; nlh = nlmsg_hdr(skb); |