From: syzbot <syzbot+fe63e4d633540f230624@syzkaller.appspotmail.com>
To: linux-kernel@vger.kernel.org, syedtayyabfarooq08@gmail.com,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [serial?] KASAN: slab-use-after-free Write in tty_init_dev
Date: Wed, 09 Sep 2026 06:19:02 -0700 [thread overview]
Message-ID: <6aa15cc6.f2639fcc.29487d.0007.GAE@google.com> (raw)
In-Reply-To: <20260909130533.9011-1-syedtayyabfarooq08@gmail.com>
Hello,
syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in gs_close
==================================================================
BUG: KASAN: slab-use-after-free in __raw_spin_lock_irq include/linux/spinlock_api_smp.h:165 [inline]
BUG: KASAN: slab-use-after-free in _raw_spin_lock_irq+0x36/0x50 kernel/locking/spinlock.c:189
Read of size 1 at addr ffff8880364433a0 by task syz-executor276/6040
CPU: 2 UID: 0 PID: 6040 Comm: syz-executor276 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
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
__kasan_check_byte+0x36/0x50 mm/kasan/common.c:574
kasan_check_byte include/linux/kasan.h:402 [inline]
lock_acquire kernel/locking/lockdep.c:5916 [inline]
lock_acquire+0x132/0x380 kernel/locking/lockdep.c:5899
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:165 [inline]
_raw_spin_lock_irq+0x36/0x50 kernel/locking/spinlock.c:189
spin_lock_irq include/linux/spinlock.h:377 [inline]
gs_close+0xc6/0xcd0 drivers/usb/gadget/function/u_serial.c:736
tty_release+0x40e/0x1300 drivers/tty/tty_io.c:1718
tty_open+0x31d/0xe20 drivers/tty/tty_io.c:2119
chrdev_open+0x234/0x6a0 fs/char_dev.c:411
do_dentry_open+0x6ab/0x14d0 fs/open.c:996
vfs_open+0x82/0x3f0 fs/open.c:1101
do_open fs/namei.c:4837 [inline]
path_openat+0x19fa/0x2440 fs/namei.c:5000
do_file_open+0x20e/0x430 fs/namei.c:5029
do_sys_openat2+0x10f/0x1e0 fs/open.c:1417
do_sys_open fs/open.c:1423 [inline]
__do_sys_openat fs/open.c:1439 [inline]
__se_sys_openat fs/open.c:1434 [inline]
__x64_sys_openat+0x12d/0x210 fs/open.c:1434
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb0988eba1e
Code: 08 0f 85 f5 e2 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007fb098896158 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fb0988966c0 RCX: 00007fb0988eba1e
RDX: 0000000000000002 RSI: 00007fb098937028 RDI: ffffffffffffff9c
RBP: 0000000000000021 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffd0
R13: 0000000000000000 R14: 00007ffc902179f0 R15: 00007ffc90217ad8
</TASK>
Allocated by task 6038:
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+0x2f8/0x6d0 mm/slub.c:5563
_kmalloc_noprof include/linux/slab.h:991 [inline]
_kzalloc_noprof include/linux/slab.h:1312 [inline]
gs_port_alloc drivers/usb/gadget/function/u_serial.c:1269 [inline]
gserial_alloc_line_no_console+0xac/0x740 drivers/usb/gadget/function/u_serial.c:1349
gserial_alloc_line+0x16/0xa0 drivers/usb/gadget/function/u_serial.c:1383
acm_alloc_instance+0xd9/0x160 drivers/usb/gadget/function/f_acm.c:891
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+0x525/0xd40 fs/configfs/dir.c:1369
vfs_mkdir+0x364/0x850 fs/namei.c:5410
filename_mkdirat+0x48b/0x5e0 fs/namei.c:5443
__do_sys_mkdir fs/namei.c:5470 [inline]
__se_sys_mkdir fs/namei.c:5467 [inline]
__x64_sys_mkdir+0x6b/0x90 fs/namei.c:5467
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 6038:
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:2748 [inline]
slab_free mm/slub.c:6499 [inline]
kfree+0x22b/0x6d0 mm/slub.c:6792
tty_port_destructor drivers/tty/tty_port.c:294 [inline]
kref_put include/linux/kref.h:65 [inline]
tty_port_put drivers/tty/tty_port.c:309 [inline]
tty_port_put+0x18d/0x1e0 drivers/tty/tty_port.c:306
gserial_free_port+0x13e/0x2f0 drivers/usb/gadget/function/u_serial.c:1313
gserial_free_line+0xf8/0x1e0 drivers/usb/gadget/function/u_serial.c:1330
acm_free_instance+0x3b/0x60 drivers/usb/gadget/function/f_acm.c:875
usb_put_function_instance+0x97/0xc0 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:1580
vfs_rmdir fs/namei.c:5515 [inline]
vfs_rmdir+0x328/0x8a0 fs/namei.c:5488
filename_rmdir+0x31a/0x5c0 fs/namei.c:5572
__do_sys_rmdir fs/namei.c:5595 [inline]
__se_sys_rmdir fs/namei.c:5592 [inline]
__x64_sys_rmdir+0x46/0x70 fs/namei.c:5592
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888036443000
which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 928 bytes inside of
freed 2048-byte region [ffff888036443000, ffff888036443800)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x36440
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801c042f00 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801c042f00 dead000000000100 dead000000000122
head: 0000000000000000 0000000000080008 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 6038, tgid 6038 (syz-executor276), ts 77096280293
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0xfd/0x120 mm/page_alloc.c:1871
prep_new_page mm/page_alloc.c:1879 [inline]
get_page_from_freelist+0x110d/0x35d0 mm/page_alloc.c:3943
__alloc_frozen_pages_noprof+0x2eb/0x3300 mm/page_alloc.c:5436
alloc_slab_page mm/slub.c:3347 [inline]
allocate_slab mm/slub.c:3462 [inline]
new_slab+0xa9/0x6e0 mm/slub.c:3513
refill_objects+0xe3/0x410 mm/slub.c:7410
refill_sheaf mm/slub.c:2885 [inline]
__pcs_replace_empty_main+0x35e/0x650 mm/slub.c:4774
alloc_from_pcs mm/slub.c:4850 [inline]
slab_alloc_node mm/slub.c:4984 [inline]
__kmalloc_cache_noprof+0x4f4/0x6d0 mm/slub.c:5559
_kmalloc_noprof include/linux/slab.h:991 [inline]
_kzalloc_noprof include/linux/slab.h:1312 [inline]
gs_port_alloc drivers/usb/gadget/function/u_serial.c:1269 [inline]
gserial_alloc_line_no_console+0xac/0x740 drivers/usb/gadget/function/u_serial.c:1349
gserial_alloc_line+0x16/0xa0 drivers/usb/gadget/function/u_serial.c:1383
acm_alloc_instance+0xd9/0x160 drivers/usb/gadget/function/f_acm.c:891
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+0x525/0xd40 fs/configfs/dir.c:1369
vfs_mkdir+0x364/0x850 fs/namei.c:5410
filename_mkdirat+0x48b/0x5e0 fs/namei.c:5443
page last free pid 1169 tgid 1169 ts 76886153795 stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
__free_pages_prepare mm/page_alloc.c:1418 [inline]
__free_frozen_pages+0x79f/0x10f0 mm/page_alloc.c:2962
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:4683 [inline]
slab_alloc_node mm/slub.c:4996 [inline]
kmem_cache_alloc_noprof+0x269/0x6a0 mm/slub.c:5010
copy_signal kernel/fork.c:1746 [inline]
copy_process+0x3075/0x8370 kernel/fork.c:2304
kernel_clone+0x176/0x9d0 kernel/fork.c:2766
user_mode_thread+0xd1/0x120 kernel/fork.c:2843
call_usermodehelper_exec_sync kernel/umh.c:130 [inline]
call_usermodehelper_exec_work+0x6b/0x180 kernel/umh.c:161
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
process_scheduled_works kernel/workqueue.c:3479 [inline]
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
kthread+0x373/0x450 kernel/kthread.c:436
ret_from_fork+0x730/0xd60 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:
ffff888036443280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888036443300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888036443380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888036443400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888036443480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
Tested on:
commit: 893e1178 Merge tag 'x86_urgent_for_7.3-rc3' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=167e2ef9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8c5c3949d762a91f
dashboard link: https://syzkaller.appspot.com/bug?extid=fe63e4d633540f230624
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
patch: https://syzkaller.appspot.com/x/patch.diff?x=1006d749580000
next parent reply other threads:[~2026-09-09 13:19 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20260909130533.9011-1-syedtayyabfarooq08@gmail.com>
2026-09-09 13:19 ` syzbot [this message]
[not found] <20260910060923.11410-1-syedtayyabfarooq08@gmail.com>
2026-09-10 6:25 ` syzbot
[not found] <20260909113541.8544-1-syedtayyabfarooq08@gmail.com>
2026-09-09 11:56 ` syzbot
[not found] <20260909074349.7542-1-syedtayyabfarooq08@gmail.com>
2026-09-09 7:58 ` syzbot
[not found] <20260909071013.7123-1-syedtayyabfarooq08@gmail.com>
2026-09-09 7:24 ` syzbot
2026-07-31 6:14 syzbot
2026-09-04 12:38 ` syzbot
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