[syzbot] [hams?] WARNING: refcount bug in ax25_release (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 56fb6f92854f Merge tag 'drm-next-2024-05-25' of https://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17e2d748980000
kernel config: https://syzkaller.appspot.com/x/.config?x=34e05c35ec964e75
dashboard link: https://syzkaller.appspot.com/bug?extid=33841dc6aa3e1d86b78a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6f3028c1d0fa/disk-56fb6f92.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/81203e55e7d0/vmlinux-56fb6f92.xz
kernel image: https://storage.googleapis.com/syzbot-assets/37bf21eee59d/bzImage-56fb6f92.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+33841d...@syzkaller.appspotmail.com

------------[ cut here ]------------
refcount_t: decrement hit 0; leaking memory.
WARNING: CPU: 1 PID: 19983 at lib/refcount.c:31 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:31
Modules linked in:
CPU: 1 PID: 19983 Comm: syz-executor.4 Not tainted 6.9.0-syzkaller-12277-g56fb6f92854f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
RIP: 0010:refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:31
Code: b2 00 00 00 e8 27 b8 ef fc 5b 5d c3 cc cc cc cc e8 1b b8 ef fc c6 05 fc 35 f0 0a 01 90 48 c7 c7 a0 bf 1e 8c e8 47 e8 b1 fc 90 <0f> 0b 90 90 eb d9 e8 fb b7 ef fc c6 05 d9 35 f0 0a 01 90 48 c7 c7
RSP: 0018:ffffc9001b83f908 EFLAGS: 00010246
RAX: 2a301f9112304400 RBX: ffff88807b02a664 RCX: 0000000000040000
RDX: ffffc9000b33b000 RSI: 000000000000ca38 RDI: 000000000000ca39
RBP: 0000000000000004 R08: ffffffff815846c2 R09: 1ffffffff25ededb
R10: dffffc0000000000 R11: fffffbfff25ededc R12: ffff88807b02a620
R13: 0000000000000000 R14: ffff88807b02a664 R15: dffffc0000000000
FS: 00007f475dfe66c0(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ff2b9901723 CR3: 000000007ac0a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__refcount_dec include/linux/refcount.h:336 [inline]
refcount_dec include/linux/refcount.h:351 [inline]
ref_tracker_free+0x6af/0x7e0 lib/ref_tracker.c:236
netdev_tracker_free include/linux/netdevice.h:4058 [inline]
netdev_put include/linux/netdevice.h:4075 [inline]
ax25_release+0x368/0x950 net/ax25/af_ax25.c:1069
__sock_release net/socket.c:659 [inline]
sock_close+0xbc/0x240 net/socket.c:1421
__fput+0x406/0x8b0 fs/file_table.c:422
task_work_run+0x24f/0x310 kernel/task_work.c:180
get_signal+0x15e6/0x1740 kernel/signal.c:2681
arch_do_signal_or_restart+0x96/0x860 arch/x86/kernel/signal.c:310
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0xc9/0x370 kernel/entry/common.c:218
do_syscall_64+0x100/0x230 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f475d27cee9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 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 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f475dfe60c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: 0000000000000000 RBX: 00007f475d3ac050 RCX: 00007f475d27cee9
RDX: 0000000000000019 RSI: 0000000000000101 RDI: 0000000000000004
RBP: 00007f475d2c949e R08: 0000000000000010 R09: 0000000000000000
R10: 00000000200002c0 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f475d3ac050 R15: 00007ffd8cfeadc8
</TASK>


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

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

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 568ebdaba637 MAINTAINERS: adjust file entry in FREESCALE Q..
git tree: net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=132d6dea980000
kernel config: https://syzkaller.appspot.com/x/.config?x=e78fc116033e0ab7

dashboard link: https://syzkaller.appspot.com/bug?extid=33841dc6aa3e1d86b78a
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=121324ae980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1607cdda980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1d754ea220a6/disk-568ebdab.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/232f2545fca4/vmlinux-568ebdab.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6398bb41810d/bzImage-568ebdab.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+33841d...@syzkaller.appspotmail.com

------------[ cut here ]------------
refcount_t: decrement hit 0; leaking memory.

WARNING: CPU: 0 PID: 5091 at lib/refcount.c:31 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:31
Modules linked in:
CPU: 0 PID: 5091 Comm: syz-executor127 Not tainted 6.10.0-rc4-syzkaller-00875-g568ebdaba637 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024

RIP: 0010:refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:31

Code: b2 00 00 00 e8 37 51 e7 fc 5b 5d c3 cc cc cc cc e8 2b 51 e7 fc c6 05 d6 3f e9 0a 01 90 48 c7 c7 a0 97 1f 8c e8 67 81 a9 fc 90 <0f> 0b 90 90 eb d9 e8 0b 51 e7 fc c6 05 b3 3f e9 0a 01 90 48 c7 c7
RSP: 0018:ffffc900033df9c8 EFLAGS: 00010246
RAX: 9aea901d1711a200 RBX: ffff88807bf2c664 RCX: ffff8880287d9e00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000004 R08: ffffffff81585822 R09: fffffbfff1c39994
R10: dffffc0000000000 R11: fffffbfff1c39994 R12: ffff88807bf2c620
R13: 0000000000000000 R14: ffff88807bf2c664 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9400000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00007fa556961110 CR3: 0000000075faa000 CR4: 00000000003506f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
__refcount_dec include/linux/refcount.h:336 [inline]
refcount_dec include/linux/refcount.h:351 [inline]
ref_tracker_free+0x6af/0x7e0 lib/ref_tracker.c:236

netdev_tracker_free include/linux/netdevice.h:4056 [inline]
netdev_put include/linux/netdevice.h:4073 [inline]

ax25_release+0x368/0x950 net/ax25/af_ax25.c:1069
__sock_release net/socket.c:659 [inline]
sock_close+0xbc/0x240 net/socket.c:1421
__fput+0x406/0x8b0 fs/file_table.c:422
task_work_run+0x24f/0x310 kernel/task_work.c:180

exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0xa27/0x27e0 kernel/exit.c:874
do_group_exit+0x207/0x2c0 kernel/exit.c:1023
__do_sys_exit_group kernel/exit.c:1034 [inline]
__se_sys_exit_group kernel/exit.c:1032 [inline]
__x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1032
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa5568e5c49
Code: Unable to access opcode bytes at 0x7fa5568e5c1f.
RSP: 002b:00007ffc83eaf9b8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fa5568e5c49
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007fa5569602b0 R08: ffffffffffffffb8 R09: 0000000000000006
R10: 00000000200003c0 R11: 0000000000000246 R12: 00007fa5569602b0
R13: 0000000000000000 R14: 00007fa556960d00 R15: 00007fa5568b6e90
</TASK>


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

[syzbot]

syzbot has bisected this issue to:

commit 9fd75b66b8f68498454d685dc4ba13192ae069b0
Author: Duoming Zhou <duo...@zju.edu.cn>
Date: Fri Mar 18 00:54:04 2022 +0000

ax25: Fix refcount leaks caused by ax25_cb_del()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=12f83301980000
start commit: 568ebdaba637 MAINTAINERS: adjust file entry in FREESCALE Q..
git tree: net-next
final oops: https://syzkaller.appspot.com/x/report.txt?x=11f83301980000
console output: https://syzkaller.appspot.com/x/log.txt?x=16f83301980000

kernel config: https://syzkaller.appspot.com/x/.config?x=e78fc116033e0ab7
dashboard link: https://syzkaller.appspot.com/bug?extid=33841dc6aa3e1d86b78a

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=121324ae980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1607cdda980000

Reported-by: syzbot+33841d...@syzkaller.appspotmail.com
Fixes: 9fd75b66b8f6 ("ax25: Fix refcount leaks caused by ax25_cb_del()")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection