From: syzbot <syzbot+bca09f5d8b843bbf7571@syzkaller.appspotmail.com>
To: gregkh@linuxfoundation.org, jirislaby@kernel.org,
linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org,
syzkaller-bugs@googlegroups.com
Subject: [syzbot] [serial?] KASAN: slab-use-after-free Write in release_tty
Date: Mon, 10 Aug 2026 19:03:36 -0700 [thread overview]
Message-ID: <6a7a82f8.01d0871a.3a0d52.00b9.GAE@google.com> (raw)
Hello,
syzbot found the following issue on:
HEAD commit: 0d8395707651 Merge tag 'soc-fixes-7.2-2' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=160e929e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=145fa60d73086782
dashboard link: https://syzkaller.appspot.com/bug?extid=bca09f5d8b843bbf7571
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6ecb6d42b95f/disk-0d839570.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/53481594a62a/vmlinux-0d839570.xz
kernel image: https://storage.googleapis.com/syzbot-assets/11ad64300b74/bzImage-0d839570.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bca09f5d8b843bbf7571@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-use-after-free in release_tty+0x5a8/0x5f0 drivers/tty/tty_io.c:1584
Write of size 8 at addr ffff88803487f128 by task syz.4.4594/23193
CPU: 0 UID: 0 PID: 23193 Comm: syz.4.4594 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x13d/0x4b0 mm/kasan/report.c:482
kasan_report+0xdf/0x1c0 mm/kasan/report.c:595
release_tty+0x5a8/0x5f0 drivers/tty/tty_io.c:1584
tty_release_struct+0xb7/0xe0 drivers/tty/tty_io.c:1692
tty_release+0xd7a/0x1300 drivers/tty/tty_io.c:1852
__fput+0x3ff/0xb50 fs/file_table.c:512
task_work_run+0x150/0x240 kernel/task_work.c:233
get_signal+0x1bd/0x21e0 kernel/signal.c:2818
arch_do_signal_or_restart+0x91/0x7e0 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
exit_to_user_mode_loop+0x139/0x6f0 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
do_syscall_64+0x666/0x870 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fad4599e0d9
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:00007fad468d8028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: fffffffffffffe00 RBX: 00007fad45c26090 RCX: 00007fad4599e0d9
RDX: 0000000000000001 RSI: 0000200000000a00 RDI: 0000000000000006
RBP: 00007fad45a35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fad45c26128 R14: 00007fad45c26090 R15: 00007ffe36320cc8
</TASK>
Allocated by task 8740:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__kmalloc_cache_noprof+0x2e5/0x6c0 mm/slub.c:5489
_kmalloc_noprof include/linux/slab.h:988 [inline]
_kzalloc_noprof include/linux/slab.h:1309 [inline]
gs_port_alloc drivers/usb/gadget/function/u_serial.c:1218 [inline]
gserial_alloc_line_no_console+0xac/0x710 drivers/usb/gadget/function/u_serial.c:1298
obex_alloc_inst+0x86/0x100 drivers/usb/gadget/function/f_obex.c:434
try_get_usb_function_instance+0x136/0x1f0 drivers/usb/gadget/functions.c:28
usb_get_function_instance+0x16/0x70 drivers/usb/gadget/functions.c:44
function_make+0x18c/0x3f0 drivers/usb/gadget/configfs.c:626
configfs_mkdir+0x51e/0xb70 fs/configfs/dir.c:1360
vfs_mkdir+0x361/0x850 fs/namei.c:5276
filename_mkdirat+0x48b/0x5e0 fs/namei.c:5309
__do_sys_mkdirat fs/namei.c:5330 [inline]
__se_sys_mkdirat fs/namei.c:5327 [inline]
__x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5327
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 23197:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5f/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2677 [inline]
slab_free mm/slub.c:6377 [inline]
kfree+0x22b/0x6c0 mm/slub.c:6692
gserial_free_port+0x146/0x2f0 drivers/usb/gadget/function/u_serial.c:1262
gserial_free_line+0xf8/0x1e0 drivers/usb/gadget/function/u_serial.c:1279
obex_free_inst+0x3b/0x50 drivers/usb/gadget/function/f_obex.c:420
usb_put_function_instance+0x89/0xc0 drivers/usb/gadget/functions.c:77
config_item_cleanup+0x146/0x240 fs/configfs/item.c:128
config_item_release fs/configfs/item.c:137 [inline]
kref_put include/linux/kref.h:65 [inline]
config_item_put fs/configfs/item.c:149 [inline]
config_item_put+0x93/0xb0 fs/configfs/item.c:146
configfs_rmdir+0x5e3/0x950 fs/configfs/dir.c:1571
vfs_rmdir fs/namei.c:5381 [inline]
vfs_rmdir+0x328/0x8a0 fs/namei.c:5354
filename_rmdir+0x31a/0x5c0 fs/namei.c:5438
__do_sys_rmdir fs/namei.c:5461 [inline]
__se_sys_rmdir fs/namei.c:5458 [inline]
__x64_sys_rmdir+0x46/0x70 fs/namei.c:5458
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff88803487f000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 296 bytes inside of
freed 2048-byte region [ffff88803487f000, ffff88803487f800)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88803487c000 pfn:0x34878
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88813fe28000 ffffea0001fa6a10 ffffea000158d010
raw: ffff88803487c000 0000000800080006 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88813fe28000 ffffea0001fa6a10 ffffea000158d010
head: ffff88803487c000 0000000800080006 00000000f5000000 0000000000000000
head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd28c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5608, tgid 5608 (syz-executor), ts 68804263185, free_ts 68789261014
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1859
prep_new_page mm/page_alloc.c:1867 [inline]
get_page_from_freelist+0xf48/0x3530 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x299/0x2dc0 mm/page_alloc.c:5304
alloc_slab_page mm/slub.c:3266 [inline]
allocate_slab mm/slub.c:3380 [inline]
new_slab+0xa2/0x640 mm/slub.c:3426
refill_objects+0xe3/0x410 mm/slub.c:7310
refill_sheaf mm/slub.c:2804 [inline]
__pcs_replace_empty_main+0x376/0x680 mm/slub.c:4675
alloc_from_pcs mm/slub.c:4773 [inline]
slab_alloc_node mm/slub.c:4905 [inline]
__do_kmalloc_node mm/slub.c:5333 [inline]
__kmalloc_node_track_caller_noprof+0x679/0x830 mm/slub.c:5471
kmalloc_reserve+0xe8/0x350 net/core/skbuff.c:637
pskb_expand_head+0x249/0x10e0 net/core/skbuff.c:2312
netlink_trim+0x22d/0x2f0 net/netlink/af_netlink.c:1300
netlink_broadcast_filtered+0x6d/0xf20 net/netlink/af_netlink.c:1518
nlmsg_multicast_filtered include/net/netlink.h:1165 [inline]
nlmsg_multicast include/net/netlink.h:1184 [inline]
nlmsg_notify+0xb1/0x290 net/netlink/af_netlink.c:2599
rtnl_notify net/core/rtnetlink.c:963 [inline]
rtmsg_ifinfo_send net/core/rtnetlink.c:4553 [inline]
rtmsg_ifinfo_event net/core/rtnetlink.c:4569 [inline]
rtmsg_ifinfo_event net/core/rtnetlink.c:4556 [inline]
rtnetlink_event+0x1b3/0x1f0 net/core/rtnetlink.c:7136
notifier_call_chain+0x99/0x3f0 kernel/notifier.c:85
call_netdevice_notifiers_info+0xbe/0x110 net/core/dev.c:2250
call_netdevice_notifiers_extack net/core/dev.c:2288 [inline]
call_netdevice_notifiers net/core/dev.c:2302 [inline]
netif_set_mac_address+0x370/0x4a0 net/core/dev.c:10002
page last free pid 5730 tgid 5730 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0x79f/0x1090 mm/page_alloc.c:2950
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x47/0xf0 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4584 [inline]
slab_alloc_node mm/slub.c:4917 [inline]
kmem_cache_alloc_node_noprof+0x27d/0x6b0 mm/slub.c:4989
__alloc_skb+0x140/0x710 net/core/skbuff.c:704
alloc_skb include/linux/skbuff.h:1384 [inline]
mld_newpack.isra.0+0x18e/0xa20 net/ipv6/mcast.c:1789
add_grhead+0x299/0x340 net/ipv6/mcast.c:1900
add_grec+0x1389/0x1930 net/ipv6/mcast.c:2039
mld_send_initial_cr+0x156/0x320 net/ipv6/mcast.c:2284
mld_dad_work+0x32/0x1f0 net/ipv6/mcast.c:2310
process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
process_scheduled_works kernel/workqueue.c:3405 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
kthread+0x370/0x450 kernel/kthread.c:436
ret_from_fork+0x72b/0xd50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
Memory state around the buggy address:
ffff88803487f000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88803487f080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88803487f100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88803487f180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88803487f200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
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reply other threads:[~2026-08-11 2:03 UTC|newest]
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