| Message ID | 20170815134340.169914-1-kraigatgoog@gmail.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Tue, Aug 15, 2017 at 09:43:40AM -0400, Craig Gallek wrote: > From: Craig Gallek <kraig@google.com> > > 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> Andrew
From: Craig Gallek <kraigatgoog@gmail.com> Date: Tue, 15 Aug 2017 09:43:40 -0400 > From: Craig Gallek <kraig@google.com> > > 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. ... > Fixes: 43e665287f93 ("net-next: dsa: fix flow dissection") > Reported-by: Dmitry Vyukov <dvyukov@google.com> > Signed-off-by: Craig Gallek <kraig@google.com> Applied, thanks.
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;