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| author | Craig Gallek <kraig@google.com> | 2017-08-15 09:43:40 -0400 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-08-15 17:18:35 -0700 |
| commit | 7324157b8af19ff797b550b7b1543aa1c9c07b48 (patch) | |
| tree | 9a96ad38fc443641f77df7f2d0e3899e55e623f7 /net/core | |
| parent | df9a21f11f14e393ca48689e1d4b596c4d9200e5 (diff) | |
| download | linux-stable-7324157b8af19ff797b550b7b1543aa1c9c07b48.tar.gz linux-stable-7324157b8af19ff797b550b7b1543aa1c9c07b48.tar.bz2 linux-stable-7324157b8af19ff797b550b7b1543aa1c9c07b48.zip | |
dsa: fix flow disector null pointer
A recent change to fix up DSA device behavior made the assumption that
all skbs passing through the flow disector will be associated with a
device. This does not appear to be a safe assumption. Syzkaller found
the crash below by attaching a BPF socket filter that tries to find the
payload offset of a packet passing between two unix sockets.
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:
CPU: 0 PID: 2940 Comm: syzkaller872007 Not tainted 4.13.0-rc4-next-20170811 #1
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8801d1b425c0 task.stack: ffff8801d0bc0000
RIP: 0010:__skb_flow_dissect+0xdcd/0x3ae0 net/core/flow_dissector.c:445
RSP: 0018:ffff8801d0bc7340 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000060 RSI: ffffffff856dc080 RDI: 0000000000000300
RBP: ffff8801d0bc7870 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000008 R11: ffffed003a178f1e R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff856dc080 R15: ffff8801ce223140
FS: 00000000016ed880(0000) GS:ffff8801dc000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020008000 CR3: 00000001ce22d000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
skb_flow_dissect_flow_keys include/linux/skbuff.h:1176 [inline]
skb_get_poff+0x9a/0x1a0 net/core/flow_dissector.c:1079
______skb_get_pay_offset net/core/filter.c:114 [inline]
__skb_get_pay_offset+0x15/0x20 net/core/filter.c:112
Code: 80 3c 02 00 44 89 6d 10 0f 85 44 2b 00 00 4d 8b 67 20 48 b8 00 00 00 00 00 fc ff df 49 8d bc 24 00 03 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 13 2b 00 00 4d 8b a4 24 00 03 00 00 4d 85 e4
RIP: __skb_flow_dissect+0xdcd/0x3ae0 net/core/flow_dissector.c:445 RSP: ffff8801d0bc7340
Fixes: 43e665287f93 ("net-next: dsa: fix flow dissection")
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Craig Gallek <kraig@google.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core')
| -rw-r--r-- | net/core/flow_dissector.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c index 79b9c06c83ad..e2eaa1ff948d 100644 --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -442,7 +442,7 @@ bool __skb_flow_dissect(const struct sk_buff *skb, nhoff = skb_network_offset(skb); hlen = skb_headlen(skb); #if IS_ENABLED(CONFIG_NET_DSA) - if (unlikely(netdev_uses_dsa(skb->dev))) { + if (unlikely(skb->dev && netdev_uses_dsa(skb->dev))) { const struct dsa_device_ops *ops; int offset; |