From: syzbot <syzbot+bb9127e278fa198e110c@syzkaller.appspotmail.com>
To: linux-kernel@vger.kernel.org, phil@nwl.cc,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [netfilter?] KASAN: use-after-free Read in nf_hook_entry_head
Date: Thu, 05 Mar 2026 03:09:02 -0800 [thread overview]
Message-ID: <69a9644e.a70a0220.2e49e0.0005.GAE@google.com> (raw)
In-Reply-To: <aaldbOUpumbS940Z@orbyte.nwl.cc>
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: use-after-free Read in nf_hook_entry_head
nft_flowtable_event: unregistering device syzkaller0@ffff88805fae4000 in ops @ffff888035bb2180 of hook @ffff888035bb2200 with flowtable @ffff88807ca60800
==================================================================
BUG: KASAN: use-after-free in read_pnet include/net/net_namespace.h:419 [inline]
BUG: KASAN: use-after-free in dev_net include/linux/netdevice.h:2741 [inline]
BUG: KASAN: use-after-free in nf_hook_entry_head+0x1f1/0x2c0 net/netfilter/core.c:319
Read of size 8 at addr ffff88805fae4108 by task syz.0.20/6546
CPU: 0 UID: 0 PID: 6546 Comm: syz.0.20 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xba/0x230 mm/kasan/report.c:482
kasan_report+0x117/0x150 mm/kasan/report.c:595
read_pnet include/net/net_namespace.h:419 [inline]
dev_net include/linux/netdevice.h:2741 [inline]
nf_hook_entry_head+0x1f1/0x2c0 net/netfilter/core.c:319
__nf_unregister_net_hook+0x74/0x6f0 net/netfilter/core.c:491
nft_unregister_flowtable_ops net/netfilter/nf_tables_api.c:9061 [inline]
__nft_unregister_flowtable_net_hooks net/netfilter/nf_tables_api.c:9076 [inline]
__nft_release_hook net/netfilter/nf_tables_api.c:12071 [inline]
nft_rcv_nl_event+0x7b8/0xdb0 net/netfilter/nf_tables_api.c:12184
notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
blocking_notifier_call_chain+0x6a/0x90 kernel/notifier.c:380
netlink_release+0x123b/0x1ad0 net/netlink/af_netlink.c:761
__sock_release net/socket.c:662 [inline]
sock_close+0xc3/0x240 net/socket.c:1455
__fput+0x44f/0xa70 fs/file_table.c:469
task_work_run+0x1d9/0x270 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1a96f9c629
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff6d5e3748 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f1a97217da0 RCX: 00007f1a96f9c629
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f1a97217da0 R08: 00007f1a97216128 R09: 0000000000000000
R10: 000000000003fdb8 R11: 0000000000000246 R12: 000000000002256b
R13: 00007f1a9721609c R14: 0000000000022267 R15: 00007fff6d5e3850
</TASK>
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88805fae5d40 pfn:0x5fae4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea00017ecd08 ffff88813fffbdd0 0000000000000000
raw: ffff88805fae5d40 0000000000000002 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x446dc0(GFP_KERNEL_ACCOUNT|__GFP_ZERO|__GFP_NOWARN|__GFP_RETRY_MAYFAIL|__GFP_COMP), pid 6548, tgid 6546 (syz.0.20), ts 139889058982, free_ts 140000844378
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x231/0x280 mm/page_alloc.c:1888
prep_new_page mm/page_alloc.c:1896 [inline]
get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3961
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5249
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2485
___kmalloc_large_node+0x4e/0x150 mm/slub.c:5118
__kmalloc_large_node_noprof+0x18/0x90 mm/slub.c:5149
__do_kmalloc_node mm/slub.c:5165 [inline]
__kvmalloc_node_noprof+0x7b/0x8a0 mm/slub.c:6668
alloc_netdev_mqs+0xa6/0x11b0 net/core/dev.c:12012
tun_set_iff+0x532/0xf00 drivers/net/tun.c:2778
__tun_chr_ioctl+0x7bb/0x1e10 drivers/net/tun.c:3088
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 6546 tgid 6546 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1432 [inline]
__free_frozen_pages+0xc00/0xd90 mm/page_alloc.c:2977
device_release+0x9e/0x1d0 drivers/base/core.c:-1
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x228/0x560 lib/kobject.c:737
netdev_run_todo+0xc75/0xde0 net/core/dev.c:11713
tun_detach drivers/net/tun.c:640 [inline]
tun_chr_close+0x13c/0x1c0 drivers/net/tun.c:3436
__fput+0x44f/0xa70 fs/file_table.c:469
task_work_run+0x1d9/0x270 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff88805fae4000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88805fae4080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88805fae4100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88805fae4180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88805fae4200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
Tested on:
commit: 4c51f90d selftests/bpf: Add powerpc support for get_pr..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=111bbe4a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6d9e410399043c26
dashboard link: https://syzkaller.appspot.com/bug?extid=bb9127e278fa198e110c
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch: https://syzkaller.appspot.com/x/patch.diff?x=121b2b5a580000
next parent reply other threads:[~2026-03-05 11:09 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <aaldbOUpumbS940Z@orbyte.nwl.cc>
2026-03-05 11:09 ` syzbot [this message]
[not found] <aahsfpxh9fXPDM9w@orbyte.nwl.cc>
2026-03-04 22:04 ` [syzbot] [netfilter?] KASAN: use-after-free Read in nf_hook_entry_head syzbot
[not found] <aahLgP1Yf1wH0d3U@orbyte.nwl.cc>
2026-03-04 15:34 ` syzbot
[not found] <aahJ1IwXLdc2-BYT@orbyte.nwl.cc>
2026-03-04 15:05 ` syzbot
[not found] <aahHfuzSx1EiUYwh@orbyte.nwl.cc>
2026-03-04 14:53 ` syzbot
[not found] <aag10N-nUBMVDdAm@strlen.de>
2026-03-04 14:17 ` syzbot
[not found] <5162c1cf-4f5e-4852-a60c-1ed0fa2e6e3d@igalia.com>
2026-03-02 15:42 ` syzbot
2026-02-19 10:03 syzbot
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