[syzbot] [net?] general protection fault in qdisc_create

[syzbot <syzbot+84339b9e7330daae4d66@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    c2b2ee36250d bridge: cfm: fix enum typo in br_cc_ccm_tx_pa..
git tree:       net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=15812036e80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a4e9ca8e3c104d2a
dashboard link: https://syzkaller.appspot.com/bug?extid=84339b9e7330daae4d66
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13535445e80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=15fed8f6e80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7344dc892eab/disk-c2b2ee36.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b5d04995c162/vmlinux-c2b2ee36.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9558856ab7f4/bzImage-c2b2ee36.xz

The issue was bisected to:

commit 913b47d3424e7d99eaf34b798c47dfa840c64a08
Author: Victor Nogueira <victor@mojatatu.com>
Date:   Tue Dec 19 18:16:19 2023 +0000

    net/sched: Introduce tc block netdev tracking infra

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11992409e80000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=13992409e80000
console output: https://syzkaller.appspot.com/x/log.txt?x=15992409e80000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+84339b9e7330daae4d66@syzkaller.appspotmail.com
Fixes: 913b47d3424e ("net/sched: Introduce tc block netdev tracking infra")

general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
CPU: 1 PID: 5061 Comm: syz-executor323 Not tainted 6.7.0-rc6-syzkaller-01658-gc2b2ee36250d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
RIP: 0010:qdisc_block_add_dev net/sched/sch_api.c:1190 [inline]
RIP: 0010:qdisc_create+0x69e/0x1430 net/sched/sch_api.c:1390
Code: ea 03 80 3c 02 00 0f 85 50 0c 00 00 4c 8b 6d 08 49 8d 45 48 48 89 c2 48 89 44 24 18 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 0f 0c 00 00 31 d2 be f2 ff 00 00 48 89 df 41 ff
RSP: 0018:ffffc9000398f420 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffff88802688c800 RCX: ffffffff888dbd56
RDX: 0000000000000009 RSI: ffffffff888db6fe RDI: ffffffff8f19bde8
RBP: ffffffff8f19bde0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff88804fd64000
R13: 0000000000000000 R14: 0000000000000001 R15: ffffffff8f19bde0
FS:  0000555556ef3380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020001248 CR3: 0000000027f71000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 tc_modify_qdisc+0x4d5/0x1c30 net/sched/sch_api.c:1788
 rtnetlink_rcv_msg+0x3c7/0xe00 net/core/rtnetlink.c:6615
 netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2543
 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline]
 netlink_unicast+0x53b/0x810 net/netlink/af_netlink.c:1367
 netlink_sendmsg+0x8b7/0xd70 net/netlink/af_netlink.c:1908
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0xd5/0x180 net/socket.c:745
 ____sys_sendmsg+0x6ac/0x940 net/socket.c:2584
 ___sys_sendmsg+0x135/0x1d0 net/socket.c:2638
 __sys_sendmsg+0x117/0x1e0 net/socket.c:2667
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x40/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f9733a8a8b9
Code: 48 83 c4 28 c3 e8 27 18 00 00 0f 1f 80 00 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd50d7c048 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f9733a8a8b9
RDX: 0000000000000000 RSI: 0000000020005840 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 00007ffd50d7c0c0
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd50d7c248 R14: 0000000000000001 R15: 0000000000000001
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:qdisc_block_add_dev net/sched/sch_api.c:1190 [inline]
RIP: 0010:qdisc_create+0x69e/0x1430 net/sched/sch_api.c:1390
Code: ea 03 80 3c 02 00 0f 85 50 0c 00 00 4c 8b 6d 08 49 8d 45 48 48 89 c2 48 89 44 24 18 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 0f 0c 00 00 31 d2 be f2 ff 00 00 48 89 df 41 ff
RSP: 0018:ffffc9000398f420 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: ffff88802688c800 RCX: ffffffff888dbd56
RDX: 0000000000000009 RSI: ffffffff888db6fe RDI: ffffffff8f19bde8
RBP: ffffffff8f19bde0 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000001 R12: ffff88804fd64000
R13: 0000000000000000 R14: 0000000000000001 R15: ffffffff8f19bde0
FS:  0000555556ef3380(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020001248 CR3: 0000000027f71000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	03 80 3c 02 00 0f    	add    0xf00023c(%rax),%eax
   6:	85 50 0c             	test   %edx,0xc(%rax)
   9:	00 00                	add    %al,(%rax)
   b:	4c 8b 6d 08          	mov    0x8(%rbp),%r13
   f:	49 8d 45 48          	lea    0x48(%r13),%rax
  13:	48 89 c2             	mov    %rax,%rdx
  16:	48 89 44 24 18       	mov    %rax,0x18(%rsp)
  1b:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  22:	fc ff df
  25:	48 c1 ea 03          	shr    $0x3,%rdx
* 29:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2d:	0f 85 0f 0c 00 00    	jne    0xc42
  33:	31 d2                	xor    %edx,%edx
  35:	be f2 ff 00 00       	mov    $0xfff2,%esi
  3a:	48 89 df             	mov    %rbx,%rdi
  3d:	41                   	rex.B
  3e:	ff                   	.byte 0xff


---
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