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authorPablo Neira <pablo@netfilter.org>2013-06-28 05:04:23 +0400
committerDavid S. Miller <davem@davemloft.net>2013-06-28 09:44:16 +0400
commit3a36515f729458c8efa0c124c7262d5843ad5c37 (patch)
tree75924228bbebccdbbbbe1c8cca9b65d121843a0a /net/ipv4
parent5e6700b3bf98fe98d630bf9c939ad4c85ce95592 (diff)
downloadlinux-3a36515f729458c8efa0c124c7262d5843ad5c37.tar.xz
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.c2
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);