On Mon, Aug 19, 2019 at 10:44 PM Xin Long [off-list ref] wrote:

On Sun, Aug 18, 2019 at 10:13 PM Dmitry Vyukov [off-list ref] wrote:

quoted

On Sun, Aug 18, 2019 at 7:07 AM Xin Long [off-list ref] wrote:

quoted

On Sat, Aug 17, 2019 at 2:38 AM syzbot
[off-list ref] wrote:

quoted

Hello,

syzbot found the following crash on:

HEAD commit:    459c5fb4 Merge branch 'mscc-PTP-support'
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13f2d33c600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d4cf1ffb87d590d7
dashboard link: https://syzkaller.appspot.com/bug?extid=eb349eeee854e389c36d
compiler:       gcc (GCC) 9.0.0 20181231 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=111849e2600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1442c25a600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+eb349eeee854e389c36d@syzkaller.appspotmail.com

------------[ cut here ]------------
kernel BUG at include/linux/skbuff.h:2225!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9030 Comm: syz-executor649 Not tainted 5.3.0-rc3+ #134
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:__skb_pull include/linux/skbuff.h:2225 [inline]
RIP: 0010:__skb_pull include/linux/skbuff.h:2222 [inline]
RIP: 0010:skb_pull_inline include/linux/skbuff.h:2231 [inline]
RIP: 0010:skb_pull+0xea/0x110 net/core/skbuff.c:1902
Code: 9d c8 00 00 00 49 89 dc 49 89 9d c8 00 00 00 e8 9c e5 dd fb 4c 89 e0
5b 41 5c 41 5d 41 5e 5d c3 45 31 e4 eb ea e8 86 e5 dd fb <0f> 0b e8 df 13
18 fc e9 44 ff ff ff e8 d5 13 18 fc eb 8a e8 ee 13
RSP: 0018:ffff88808ac96e10 EFLAGS: 00010293
RAX: ffff88809c546000 RBX: 0000000000000004 RCX: ffffffff8594a3a6
RDX: 0000000000000000 RSI: ffffffff8594a3fa RDI: 0000000000000004
RBP: ffff88808ac96e30 R08: ffff88809c546000 R09: fffffbfff14a8f4f
R10: fffffbfff14a8f4e R11: ffffffff8a547a77 R12: 0000000095e28bcc
R13: ffff88808ac97478 R14: 00000000ffff8880 R15: ffff88808ac97478
FS:  0000555556549880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000100 CR3: 0000000089c3c000 CR4: 00000000001406f0
Call Trace:
  sctp_inq_pop+0x2f1/0xd80 net/sctp/inqueue.c:202
  sctp_endpoint_bh_rcv+0x184/0x8d0 net/sctp/endpointola.c:385
  sctp_inq_push+0x1e4/0x280 net/sctp/inqueue.c:80
  sctp_rcv+0x2807/0x3590 net/sctp/input.c:256
  sctp6_rcv+0x17/0x30 net/sctp/ipv6.c:1049
  ip6_protocol_deliver_rcu+0x2fe/0x1660 net/ipv6/ip6_input.c:397
  ip6_input_finish+0x84/0x170 net/ipv6/ip6_input.c:438
  NF_HOOK include/linux/netfilter.h:305 [inline]
  NF_HOOK include/linux/netfilter.h:299 [inline]
  ip6_input+0xe4/0x3f0 net/ipv6/ip6_input.c:447
  dst_input include/net/dst.h:442 [inline]
  ip6_sublist_rcv_finish+0x98/0x1e0 net/ipv6/ip6_input.c:84

Looks skb_list_del_init() should be called in ip6_sublist_rcv_finish,
as does in ip_sublist_rcv_finish().

This was recently introduced, right? Only in net-next and linux-next.
Otherwise, is it a remote DoS? If so and if it's present in any
releases, may need a CVE.

I need to reproduce and confirm it, will let you know.

The panic could be triggered since the  listified RX support for
GRO_NORMAL skbs:
  https://patchwork.ozlabs.org/cover/1142808/
(it's only in net-next now, I will post a fix soon)

But the bug itself is not really related with the patch series above.
the issue here is pretty much like what this patch fixed:
  https://patchwork.ozlabs.org/patch/942541/
I didn't see a CVE for it, maybe because it was only on net-next too.