syzbot
KASAN: null-ptr-deref Read in tcf_idrinfo_destroy (2)
Status:
premoderation: reported on 2026/07/31 01:46
Reported-by: syzbot+e19b4a93eaad1b79c1e2@syzkaller.appspotmail.com
First crash: 4d19h, last: 4d19h
Sample crash report:
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:72 [inline]
BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
BUG: KASAN: null-ptr-deref in __tcf_idr_release net/sched/act_api.c:416 [inline]
BUG: KASAN: null-ptr-deref in tcf_idrinfo_destroy+0xbf/0x220 net/sched/act_api.c:902
Read of size 4 at addr 0000000000000010 by task kworker/u4:10/1060
CPU: 1 PID: 1060 Comm: kworker/u4:10 Tainted: G W syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: netns cleanup_net
Call Trace:
<TASK>
__dump_stack+0x21/0x24 lib/dump_stack.c:88
dump_stack_lvl+0x110/0x170 lib/dump_stack.c:106
print_report+0x3d/0x60 mm/kasan/report.c:423
kasan_report+0x122/0x150 mm/kasan/report.c:524
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189
__kasan_check_read+0x11/0x20 mm/kasan/shadow.c:31
instrument_atomic_read include/linux/instrumented.h:72 [inline]
atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
__tcf_idr_release net/sched/act_api.c:416 [inline]
tcf_idrinfo_destroy+0xbf/0x220 net/sched/act_api.c:902
tc_action_net_exit include/net/act_api.h:176 [inline]
gact_exit_net+0xe3/0x150 net/sched/act_gact.c:307
ops_exit_list net/core/net_namespace.c:177 [inline]
cleanup_net+0x630/0xb10 net/core/net_namespace.c:604
process_one_work+0x717/0xc30 kernel/workqueue.c:2302
worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449
kthread+0x281/0x320 kernel/kthread.c:386
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
==================================================================
general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 1 PID: 1060 Comm: kworker/u4:10 Tainted: G B W syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: netns cleanup_net
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:29 [inline]
RIP: 0010:atomic_read include/linux/atomic/atomic-instrumented.h:28 [inline]
RIP: 0010:__tcf_idr_release net/sched/act_api.c:416 [inline]
RIP: 0010:tcf_idrinfo_destroy+0xc6/0x220 net/sched/act_api.c:902
Code: 40 e8 4e 2b e1 00 48 85 c0 0f 84 1a 01 00 00 49 89 c4 4c 8d 68 20 4c 89 ef be 04 00 00 00 e8 81 f1 aa fd 4c 89 e8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 ba 00 00 00 45 8b 6d 00 31 ff 44 89 ee
RSP: 0018:ffffc90011407b60 EFLAGS: 00010202
RAX: 0000000000000002 RBX: ffff888136540db0 RCX: ffff888141f4e540
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90011407c08 R08: ffffffff87b757e7 R09: 1ffffffff0f6eafc
R10: dffffc0000000000 R11: fffffbfff0f6eafd R12: fffffffffffffff0
R13: 0000000000000010 R14: ffffffff877adb90 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcf373eb700 CR3: 0000000128efa000 CR4: 00000000003526a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
tc_action_net_exit include/net/act_api.h:176 [inline]
gact_exit_net+0xe3/0x150 net/sched/act_gact.c:307
ops_exit_list net/core/net_namespace.c:177 [inline]
cleanup_net+0x630/0xb10 net/core/net_namespace.c:604
process_one_work+0x717/0xc30 kernel/workqueue.c:2302
worker_thread+0xa4d/0x11d0 kernel/workqueue.c:2449
kthread+0x281/0x320 kernel/kthread.c:386
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:29 [inline]
RIP: 0010:atomic_read include/linux/atomic/atomic-instrumented.h:28 [inline]
RIP: 0010:__tcf_idr_release net/sched/act_api.c:416 [inline]
RIP: 0010:tcf_idrinfo_destroy+0xc6/0x220 net/sched/act_api.c:902
Code: 40 e8 4e 2b e1 00 48 85 c0 0f 84 1a 01 00 00 49 89 c4 4c 8d 68 20 4c 89 ef be 04 00 00 00 e8 81 f1 aa fd 4c 89 e8 48 c1 e8 03 <42> 0f b6 04 38 84 c0 0f 85 ba 00 00 00 45 8b 6d 00 31 ff 44 89 ee
RSP: 0018:ffffc90011407b60 EFLAGS: 00010202
RAX: 0000000000000002 RBX: ffff888136540db0 RCX: ffff888141f4e540
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90011407c08 R08: ffffffff87b757e7 R09: 1ffffffff0f6eafc
R10: dffffc0000000000 R11: fffffbfff0f6eafd R12: fffffffffffffff0
R13: 0000000000000010 R14: ffffffff877adb90 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcebb5ef2f8 CR3: 0000000110087000 CR4: 00000000003526a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 40 e8 4e 2b e1 00 rex call 0xe12b54
6: 48 85 c0 test %rax,%rax
9: 0f 84 1a 01 00 00 je 0x129
f: 49 89 c4 mov %rax,%r12
12: 4c 8d 68 20 lea 0x20(%rax),%r13
16: 4c 89 ef mov %r13,%rdi
19: be 04 00 00 00 mov $0x4,%esi
1e: e8 81 f1 aa fd call 0xfdaaf1a4
23: 4c 89 e8 mov %r13,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 0f b6 04 38 movzbl (%rax,%r15,1),%eax <-- trapping instruction
2f: 84 c0 test %al,%al
31: 0f 85 ba 00 00 00 jne 0xf1
37: 45 8b 6d 00 mov 0x0(%r13),%r13d
3b: 31 ff xor %edi,%edi
3d: 44 89 ee mov %r13d,%esi
Struck through repros no longer work on HEAD.