general protection fault in tcf_generic_walker

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3f8a27f9e27b Linux 4.19.211
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11d06845b00000
kernel config: https://syzkaller.appspot.com/x/.config?x=9b9277b418617afe
dashboard link: https://syzkaller.appspot.com/bug?extid=4b03bb1f2a1c4dfbd97a
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4b03bb...@syzkaller.appspotmail.com

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: 16225 Comm: syz-executor.3 Not tainted 4.19.211-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:tcf_dump_walker net/sched/act_api.c:212 [inline]
RIP: 0010:tcf_generic_walker+0x33e/0xa20 net/sched/act_api.c:294
Code: 24 31 ff 48 89 de e8 71 44 d6 fa 48 85 db 74 3f e8 d7 42 d6 fa 48 8d 7d 30 48 ba 00 00 00 00 00 fc ff df 48 89 f8 48 c1 e8 03 <80> 3c 10 00 0f 85 d5 05 00 00 48 8b 5d 30 31 ff 48 2b 1c 24 48 89
RSP: 0018:ffff8880a1a874d8 EFLAGS: 00010202
RAX: 0000000000000004 RBX: 0000000100019b74 RCX: ffffc9000c50c000
RDX: dffffc0000000000 RSI: ffffffff868c4299 RDI: 0000000000000020
RBP: fffffffffffffff0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000007 R11: 0000000000000000 R12: ffff8880ae899500
R13: 000000000000002b R14: 000000000000002a R15: 0000000000000000
FS: 00007f5ac82e2700(0000) GS:ffff8880ba000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2d725000 CR3: 00000000b3c15000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
tc_dump_action+0x6b0/0xdb0 net/sched/act_api.c:1476
netlink_dump+0x3cf/0xc10 net/netlink/af_netlink.c:2242
__netlink_dump_start+0x4e9/0x6f0 net/netlink/af_netlink.c:2338
netlink_dump_start include/linux/netlink.h:213 [inline]
rtnetlink_rcv_msg+0x71e/0xb80 net/core/rtnetlink.c:4745
netlink_rcv_skb+0x160/0x440 net/netlink/af_netlink.c:2463
netlink_unicast_kernel net/netlink/af_netlink.c:1325 [inline]
netlink_unicast+0x4d5/0x690 net/netlink/af_netlink.c:1351
netlink_sendmsg+0x6c3/0xc50 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:651 [inline]
sock_sendmsg+0xc3/0x120 net/socket.c:661
___sys_sendmsg+0x7bb/0x8e0 net/socket.c:2227
__sys_sendmsg net/socket.c:2265 [inline]
__do_sys_sendmsg net/socket.c:2274 [inline]
__se_sys_sendmsg net/socket.c:2272 [inline]
__x64_sys_sendmsg+0x132/0x220 net/socket.c:2272
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f5acad8dae9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5ac82e2188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f5acaea1020 RCX: 00007f5acad8dae9
RDX: 0000000000000000 RSI: 0000000020000180 RDI: 0000000000000003
RBP: 00007f5acade7f6d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffea59f5eaf R14: 00007f5ac82e2300 R15: 0000000000022000
Modules linked in:
---[ end trace 6905ab48d5a18c71 ]---
RIP: 0010:tcf_dump_walker net/sched/act_api.c:212 [inline]
RIP: 0010:tcf_generic_walker+0x33e/0xa20 net/sched/act_api.c:294
Code: 24 31 ff 48 89 de e8 71 44 d6 fa 48 85 db 74 3f e8 d7 42 d6 fa 48 8d 7d 30 48 ba 00 00 00 00 00 fc ff df 48 89 f8 48 c1 e8 03 <80> 3c 10 00 0f 85 d5 05 00 00 48 8b 5d 30 31 ff 48 2b 1c 24 48 89
RSP: 0018:ffff8880a1a874d8 EFLAGS: 00010202
RAX: 0000000000000004 RBX: 0000000100019b74 RCX: ffffc9000c50c000
RDX: dffffc0000000000 RSI: ffffffff868c4299 RDI: 0000000000000020
RBP: fffffffffffffff0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000007 R11: 0000000000000000 R12: ffff8880ae899500
R13: 000000000000002b R14: 000000000000002a R15: 0000000000000000
FS: 00007f5ac82e2700(0000) GS:ffff8880ba000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2d725000 CR3: 00000000b3c15000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
0: 31 ff xor %edi,%edi
2: 48 89 de mov %rbx,%rsi
5: e8 71 44 d6 fa callq 0xfad6447b
a: 48 85 db test %rbx,%rbx
d: 74 3f je 0x4e
f: e8 d7 42 d6 fa callq 0xfad642eb
14: 48 8d 7d 30 lea 0x30(%rbp),%rdi
18: 48 ba 00 00 00 00 00 movabs $0xdffffc0000000000,%rdx
1f: fc ff df
22: 48 89 f8 mov %rdi,%rax
25: 48 c1 e8 03 shr $0x3,%rax
* 29: 80 3c 10 00 cmpb $0x0,(%rax,%rdx,1) <-- trapping instruction
2d: 0f 85 d5 05 00 00 jne 0x608
33: 48 8b 5d 30 mov 0x30(%rbp),%rbx
37: 31 ff xor %edi,%edi
39: 48 2b 1c 24 sub (%rsp),%rbx
3d: 48 rex.W
3e: 89 .byte 0x89


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.