[Android 6.1] general protection fault in htb_qlen_notify

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 2ff414a09808 Merge tag 'android14-6.1.145_r00' into androi..
git tree: android14-6.1
console+strace: https://syzkaller.appspot.com/x/log.txt?x=16b148a2580000
kernel config: https://syzkaller.appspot.com/x/.config?x=153b76a281d74878
dashboard link: https://syzkaller.appspot.com/bug?extid=fafc29ef5e05c2781c5d
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11b148a2580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17648782580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/35c1e3a91015/disk-2ff414a0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/98e6bd32eb5e/vmlinux-2ff414a0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8428e11ad271/bzImage-2ff414a0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+fafc29...@syzkaller.appspotmail.com

netlink: 4 bytes leftover after parsing attributes in process `syz-executor446'.
general protection fault, probably for non-canonical address 0xdffffc0000000037: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000001b8-0x00000000000001bf]
CPU: 0 PID: 289 Comm: syz-executor446 Not tainted 6.1.145-syzkaller-00015-g2ff414a09808 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:htb_deactivate net/sched/sch_htb.c:610 [inline]
RIP: 0010:htb_qlen_notify+0x30/0xc0 net/sched/sch_htb.c:1495
Code: 41 56 41 55 41 54 53 49 89 f6 49 89 ff 49 bc 00 00 00 00 00 fc ff df e8 4e 0f 6f fd 4d 8d ae b8 01 00 00 4c 89 eb 48 c1 eb 03 <42> 0f b6 04 23 84 c0 75 56 45 8b 65 00 31 ff 44 89 e6 e8 49 13 6f
RSP: 0018:ffffc90000df6ea8 EFLAGS: 00010202
RAX: ffffffff8400ef52 RBX: 0000000000000037 RCX: ffff88810ecb2880
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88810ee28000
RBP: ffffc90000df6ed0 R08: ffff88810ecb2880 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff8400ef30 R12: dffffc0000000000
R13: 00000000000001b8 R14: 0000000000000000 R15: ffff88810ee28000
FS: 00005555762dd380(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055a7f22cd028 CR3: 0000000124006000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
qdisc_tree_reduce_backlog+0x20a/0x360 net/sched/sch_api.c:808
sfq_change net/sched/sch_sfq.c:740 [inline]
sfq_init+0x1b59/0x2870 net/sched/sch_sfq.c:804
qdisc_create+0x7f3/0x1040 net/sched/sch_api.c:1311
tc_modify_qdisc+0x8ea/0x1900 net/sched/sch_api.c:-1
rtnetlink_rcv_msg+0x9f4/0xcf0 net/core/rtnetlink.c:6153
netlink_rcv_skb+0x1f2/0x440 net/netlink/af_netlink.c:2503
rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6171
netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline]
netlink_unicast+0x8b1/0xa30 net/netlink/af_netlink.c:1338
netlink_sendmsg+0x8aa/0xbc0 net/netlink/af_netlink.c:1860
sock_sendmsg_nosec net/socket.c:716 [inline]
__sock_sendmsg net/socket.c:728 [inline]
____sys_sendmsg+0x5a9/0x990 net/socket.c:2509
___sys_sendmsg+0x21c/0x290 net/socket.c:2563
__sys_sendmsg net/socket.c:2592 [inline]
__do_sys_sendmsg net/socket.c:2601 [inline]
__se_sys_sendmsg net/socket.c:2599 [inline]
__x64_sys_sendmsg+0x1f0/0x2c0 net/socket.c:2599
x64_sys_call+0x171/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:47
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f86b96746a9
Code: 48 83 c4 28 c3 e8 37 17 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:00007ffcd41d1388 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007ffcd41d1558 RCX: 00007f86b96746a9
RDX: 0000000000004000 RSI: 0000200000000040 RDI: 0000000000000006
RBP: 00007f86b96e7610 R08: 000000000000000a R09: 00007ffcd41d1558
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffcd41d1548 R14: 0000000000000001 R15: 0000000000000001
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:htb_deactivate net/sched/sch_htb.c:610 [inline]
RIP: 0010:htb_qlen_notify+0x30/0xc0 net/sched/sch_htb.c:1495
Code: 41 56 41 55 41 54 53 49 89 f6 49 89 ff 49 bc 00 00 00 00 00 fc ff df e8 4e 0f 6f fd 4d 8d ae b8 01 00 00 4c 89 eb 48 c1 eb 03 <42> 0f b6 04 23 84 c0 75 56 45 8b 65 00 31 ff 44 89 e6 e8 49 13 6f
RSP: 0018:ffffc90000df6ea8 EFLAGS: 00010202
RAX: ffffffff8400ef52 RBX: 0000000000000037 RCX: ffff88810ecb2880
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88810ee28000
RBP: ffffc90000df6ed0 R08: ffff88810ecb2880 R09: 0000000000000002
R10: 0000000000000000 R11: ffffffff8400ef30 R12: dffffc0000000000
R13: 00000000000001b8 R14: 0000000000000000 R15: ffff88810ee28000
FS: 00005555762dd380(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055a7f22cd028 CR3: 0000000124006000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 41 56 push %r14
2: 41 55 push %r13
4: 41 54 push %r12
6: 53 push %rbx
7: 49 89 f6 mov %rsi,%r14
a: 49 89 ff mov %rdi,%r15
d: 49 bc 00 00 00 00 00 movabs $0xdffffc0000000000,%r12
14: fc ff df
17: e8 4e 0f 6f fd call 0xfd6f0f6a
1c: 4d 8d ae b8 01 00 00 lea 0x1b8(%r14),%r13
23: 4c 89 eb mov %r13,%rbx
26: 48 c1 eb 03 shr $0x3,%rbx
* 2a: 42 0f b6 04 23 movzbl (%rbx,%r12,1),%eax <-- trapping instruction
2f: 84 c0 test %al,%al
31: 75 56 jne 0x89
33: 45 8b 65 00 mov 0x0(%r13),%r12d
37: 31 ff xor %edi,%edi
39: 44 89 e6 mov %r12d,%esi
3c: e8 .byte 0xe8
3d: 49 rex.WB
3e: 13 .byte 0x13
3f: 6f outsl %ds:(%rsi),(%dx)


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