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

[syzbot]

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 <vic...@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+84339b...@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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For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

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[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+84339b...@syzkaller.appspotmail.com

Tested on:

commit: 92de776d Merge tag 'mlx5-updates-2023-12-20' of git://..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16a43d1ae80000

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

patch: https://syzkaller.appspot.com/x/patch.diff?x=1662b9a1e80000

Note: testing is done by a robot and is best-effort only.

[Victor Nogueira]

On 31/12/2023 08:04, syzbot wrote:
> HEAD commit: c2b2ee36250d bridge: cfm: fix enum typo in br_cc_ccm_tx_pa..
> git tree: net-next

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15fed8f6e80000

#syz test

[syzbot]

For archival purposes, forwarding an incoming command email to
linux-...@vger.kernel.org, syzkall...@googlegroups.com.

***

Subject: Re: [syzbot] [net?] general protection fault in qdisc_create
Author: ji...@resnulli.us

#syz test: https://github.com/jpirko/linux_mlxsw.git wip_tc_block_fix

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+84339b...@syzkaller.appspotmail.com

Tested on:

commit: 866c2695 net: sched: move block device tracking into t..
git tree: https://github.com/jpirko/linux_mlxsw.git wip_tc_block_fix
console output: https://syzkaller.appspot.com/x/log.txt?x=165bbaa1e80000

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

Note: no patches were applied.