general protection fault in fw_change

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 76567537 Linux 4.19.119
git tree: linux-4.19.y
console output: https://syzkaller.appspot.com/x/log.txt?x=143c423fe00000
kernel config: https://syzkaller.appspot.com/x/.config?x=dd6adfe2dd5d771
dashboard link: https://syzkaller.appspot.com/bug?extid=053db877ea6b916ec201
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+053db8...@syzkaller.appspotmail.com

kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 13449 Comm: syz-executor.0 Not tainted 4.19.119-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:fw_change+0xa8c/0x1328 net/sched/cls_fw.c:305
Code: ff 41 89 c6 89 c6 e8 d3 47 a3 fb 45 85 f6 0f 85 b8 03 00 00 e8 55 46 a3 fb 48 89 da 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 e9 06 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89
RSP: 0018:ffff88804b2cf448 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90005bbc000
RDX: 0000000000000000 RSI: ffffffff85c4832b RDI: 0000000000000001
RBP: ffff88804b2cf578 R08: ffff8880427a03c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff888204a48e30 R14: 0000000000000001 R15: ffff888085fe8f00
FS: 00007f65e18a2700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000b90004 CR3: 000000006554b000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
tc_new_tfilter+0xa6b/0x1450 net/sched/cls_api.c:1320
rtnetlink_rcv_msg+0x453/0xaf0 net/core/rtnetlink.c:4777
netlink_rcv_skb+0x160/0x410 net/netlink/af_netlink.c:2455
netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
netlink_unicast+0x4d7/0x6a0 net/netlink/af_netlink.c:1344
netlink_sendmsg+0x80b/0xcd0 net/netlink/af_netlink.c:1909
sock_sendmsg_nosec net/socket.c:622 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:632
___sys_sendmsg+0x803/0x920 net/socket.c:2115
__sys_sendmsg+0xec/0x1b0 net/socket.c:2153
do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c829
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f65e18a1c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000500b00 RCX: 000000000045c829
RDX: 0000000000000000 RSI: 00000000200001c0 RDI: 0000000000000004
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000009ff R14: 00000000004ccb68 R15: 00007f65e18a26d4
Modules linked in:
---[ end trace 82a17e00f8ef3f10 ]---
RIP: 0010:fw_change+0xa8c/0x1328 net/sched/cls_fw.c:305
Code: ff 41 89 c6 89 c6 e8 d3 47 a3 fb 45 85 f6 0f 85 b8 03 00 00 e8 55 46 a3 fb 48 89 da 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 e9 06 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89
RSP: 0018:ffff88804b2cf448 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffc90005bbc000
RDX: 0000000000000000 RSI: ffffffff85c4832b RDI: 0000000000000001
RBP: ffff88804b2cf578 R08: ffff8880427a03c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
FAT-fs (loop1): bogus number of reserved sectors
R13: ffff888204a48e30 R14: 0000000000000001 R15: ffff888085fe8f00
FAT-fs (loop1): Can't find a valid FAT filesystem
FS: 00007f65e18a2700(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000080 CR3: 000000006554b000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


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[syzbot]

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