general protection fault in tc_ctl_chain

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: bd3606c29fcc rocker: Remove port_attr_bridge_flags_get ass..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=121bbf87400000
kernel config: https://syzkaller.appspot.com/x/.config?x=8572a6e4661225f4
dashboard link: https://syzkaller.appspot.com/bug?extid=eff9cae063e4b633c6c1
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11cbd404c00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17fc80d4c00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+eff9ca...@syzkaller.appspotmail.com

audit: type=1800 audit(1550028783.638:30): pid=7517 uid=0 auid=4294967295
ses=4294967295 subj==unconfined op=collect_data cause=failed(directio)
comm="startpar" name="rmnologin" dev="sda1" ino=2423 res=0
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 7669 Comm: syz-executor789 Not tainted 5.0.0-rc5+ #60
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:__lock_acquire+0x8df/0x4700 kernel/locking/lockdep.c:3215
Code: 28 00 00 00 0f 85 35 27 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f
5d c3 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 0f
85 dc 27 00 00 49 81 3c 24 20 45 9a 89 0f 84 03 f8
RSP: 0018:ffff88808b44f180 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 000000000000000c RSI: 0000000000000000 RDI: 0000000000000060
RBP: ffff88808b44f350 R08: 0000000000000001 R09: 0000000000000001
R10: ffff88808b44f570 R11: 0000000000000001 R12: 0000000000000060
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880915d4680
FS: 0000000001ef6880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000080 CR3: 0000000093549000 CR4: 00000000001406f0
Call Trace:
lock_acquire+0x16f/0x3f0 kernel/locking/lockdep.c:3841
__mutex_lock_common kernel/locking/mutex.c:925 [inline]
__mutex_lock+0xf7/0x1310 kernel/locking/mutex.c:1072
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
tc_ctl_chain+0x42f/0x11a0 net/sched/cls_api.c:2812
rtnetlink_rcv_msg+0x465/0xb00 net/core/rtnetlink.c:5192
netlink_rcv_skb+0x17a/0x460 net/netlink/af_netlink.c:2485
rtnetlink_rcv+0x1d/0x30 net/core/rtnetlink.c:5210
netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
netlink_unicast+0x536/0x720 net/netlink/af_netlink.c:1336
netlink_sendmsg+0x8ae/0xd70 net/netlink/af_netlink.c:1925
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg+0xdd/0x130 net/socket.c:631
___sys_sendmsg+0x806/0x930 net/socket.c:2136
__sys_sendmsg+0x105/0x1d0 net/socket.c:2174
__do_sys_sendmsg net/socket.c:2183 [inline]
__se_sys_sendmsg net/socket.c:2181 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2181
do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4400d9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
ff 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd09281608 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004400d9
RDX: 0000000000000000 RSI: 0000000020000080 RDI: 0000000000000003
RBP: 00000000006ca018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000401960
R13: 00000000004019f0 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 25ab48d993ef9249 ]---
RIP: 0010:__lock_acquire+0x8df/0x4700 kernel/locking/lockdep.c:3215
Code: 28 00 00 00 0f 85 35 27 00 00 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f
5d c3 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 <80> 3c 02 00 0f
85 dc 27 00 00 49 81 3c 24 20 45 9a 89 0f 84 03 f8
RSP: 0018:ffff88808b44f180 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 000000000000000c RSI: 0000000000000000 RDI: 0000000000000060
RBP: ffff88808b44f350 R08: 0000000000000001 R09: 0000000000000001
R10: ffff88808b44f570 R11: 0000000000000001 R12: 0000000000000060
R13: 0000000000000000 R14: 0000000000000000 R15: ffff8880915d4680
FS: 0000000001ef6880(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000080 CR3: 0000000093549000 CR4: 00000000001406f0


---
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[Cong Wang]

(Cc'ing Vlad, please fix it)

[Vlad Buslov]

This is fixed by Dan Carpenter's patch "net: sched: potential NULL
dereference in tcf_block_find()" that was submitted yesterday.

[Dmitry Vyukov]

On Tue, Feb 19, 2019 at 10:10 AM Vlad Buslov <vla...@mellanox.com> wrote:
>
> This is fixed by Dan Carpenter's patch "net: sched: potential NULL
> dereference in tcf_block_find()" that was submitted yesterday.

+Dan

Let's tell syzbot that this is fixed:

#syz fix: net: sched: potential NULL dereference in tcf_block_find()