From: syzbot <syzbot+ffc483dc87891d3c107b@syzkaller.appspotmail.com>
To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: [syzbot] [usb?] KASAN: slab-use-after-free Read in printer_func_unbind
Date: Thu, 08 Oct 2026 19:07:37 -0700 [thread overview]
Message-ID: <6ac84c69.70ed5d86.2ac85.0025.GAE@google.com> (raw)
Hello,
syzbot found the following issue on:
HEAD commit: f0406245cb98 Add linux-next specific files for 20261002
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1142b7f5580000
kernel config: https://syzkaller.appspot.com/x/.config?x=dfd189b706ddeebe
dashboard link: https://syzkaller.appspot.com/bug?extid=ffc483dc87891d3c107b
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/3727ac4f2c2d/disk-f0406245.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fb9b2c85f6d9/vmlinux-f0406245.xz
kernel image: https://storage.googleapis.com/syzbot-assets/738723ef945a/bzImage-f0406245.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ffc483dc87891d3c107b@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-use-after-free in printer_req_free drivers/usb/gadget/function/f_printer.c:258 [inline]
BUG: KASAN: slab-use-after-free in printer_func_unbind+0x2e6/0x6d0 drivers/usb/gadget/function/f_printer.c:1466
Read of size 8 at addr ffff8880742abb18 by task syz.1.167/6184
CPU: 1 UID: 0 PID: 6184 Comm: syz.1.167 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_address_description+0x55/0x1e0 mm/kasan/report.c:378
print_report+0x58/0x70 mm/kasan/report.c:482
kasan_report+0x117/0x150 mm/kasan/report.c:595
printer_req_free drivers/usb/gadget/function/f_printer.c:258 [inline]
printer_func_unbind+0x2e6/0x6d0 drivers/usb/gadget/function/f_printer.c:1466
purge_configs_funcs+0x248/0x3d0 drivers/usb/gadget/configfs.c:1600
configfs_composite_unbind+0xa4/0x1c0 drivers/usb/gadget/configfs.c:1846
gadget_unbind_driver+0x1cb/0x410 drivers/usb/gadget/udc/core.c:1725
device_remove drivers/base/dd.c:616 [inline]
__device_release_driver drivers/base/dd.c:1349 [inline]
device_release_driver_internal+0x48b/0x880 drivers/base/dd.c:1372
driver_detach+0x1f3/0x2d0 drivers/base/dd.c:1435
bus_remove_driver+0x226/0x320 drivers/base/bus.c:840
usb_gadget_unregister_driver+0x4e/0x70 drivers/usb/gadget/udc/core.c:1785
unregister_gadget drivers/usb/gadget/configfs.c:263 [inline]
config_usb_cfg_unlink+0x84/0x260 drivers/usb/gadget/configfs.c:502
configfs_unlink+0x44f/0x6b0 fs/configfs/symlink.c:258
vfs_unlink+0x27b/0x6d0 fs/namei.c:5662
filename_unlinkat+0x3cd/0x610 fs/namei.c:5732
__do_sys_unlinkat fs/namei.c:5761 [inline]
__se_sys_unlinkat+0x83/0x1a0 fs/namei.c:5753
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f796539e159
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:00007f79635b4028 EFLAGS: 00000246 ORIG_RAX: 0000000000000107
RAX: ffffffffffffffda RBX: 00007f7965626180 RCX: 00007f796539e159
RDX: 0000000000000000 RSI: 0000200000000440 RDI: ffffffffffffff9c
RBP: 00007f796543506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7965626218 R14: 00007f7965626180 R15: 00007ffc6fa5e9f8
</TASK>
Allocated by task 5932:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:409 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:426
kasan_kmalloc include/linux/kasan.h:263 [inline]
__kmalloc_cache_noprof+0x31c/0x600 mm/slub.c:5680
_kmalloc_noprof include/linux/slab.h:991 [inline]
_kzalloc_noprof include/linux/slab.h:1312 [inline]
dummy_alloc_request+0x7f/0x130 drivers/usb/gadget/udc/dummy_hcd.c:695
usb_ep_alloc_request+0x67/0x280 drivers/usb/gadget/udc/core.c:198
printer_req_alloc drivers/usb/gadget/function/f_printer.c:240 [inline]
printer_func_bind+0x55c/0xbc0 drivers/usb/gadget/function/f_printer.c:1150
usb_add_function+0x2e1/0x9f0 drivers/usb/gadget/composite.c:333
configfs_composite_bind+0xde0/0x1410 drivers/usb/gadget/configfs.c:1802
gadget_bind_driver+0x2ca/0x9e0 drivers/usb/gadget/udc/core.c:1663
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x254/0xae0 drivers/base/dd.c:706
__driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868
driver_probe_device+0x4f/0x240 drivers/base/dd.c:898
__driver_attach+0x339/0x600 drivers/base/dd.c:1292
bus_for_each_dev+0x23b/0x2c0 drivers/base/bus.c:386
bus_add_driver+0x38f/0x6e0 drivers/base/bus.c:771
driver_register+0x23a/0x320 drivers/base/driver.c:174
usb_gadget_register_driver_owner+0xf9/0x270 drivers/usb/gadget/udc/core.c:1753
gadget_dev_desc_UDC_store+0x1c9/0x2f0 drivers/usb/gadget/configfs.c:300
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x337/0x430 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x612/0xba0 fs/read_write.c:687
ksys_write+0x150/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 6168:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:264 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:296
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2780 [inline]
slab_free mm/slub.c:6630 [inline]
kfree+0x1c5/0x650 mm/slub.c:6923
printer_req_free drivers/usb/gadget/function/f_printer.c:259 [inline]
printer_func_unbind+0x2fa/0x6d0 drivers/usb/gadget/function/f_printer.c:1466
purge_configs_funcs+0x248/0x3d0 drivers/usb/gadget/configfs.c:1600
configfs_composite_unbind+0xa4/0x1c0 drivers/usb/gadget/configfs.c:1846
gadget_unbind_driver+0x1cb/0x410 drivers/usb/gadget/udc/core.c:1725
device_remove drivers/base/dd.c:616 [inline]
__device_release_driver drivers/base/dd.c:1349 [inline]
device_release_driver_internal+0x48b/0x880 drivers/base/dd.c:1372
driver_detach+0x1f3/0x2d0 drivers/base/dd.c:1435
bus_remove_driver+0x226/0x320 drivers/base/bus.c:840
usb_gadget_unregister_driver+0x4e/0x70 drivers/usb/gadget/udc/core.c:1785
unregister_gadget drivers/usb/gadget/configfs.c:263 [inline]
gadget_dev_desc_UDC_store+0x17a/0x2f0 drivers/usb/gadget/configfs.c:290
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x337/0x430 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x612/0xba0 fs/read_write.c:687
ksys_write+0x150/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff8880742abb00
which belongs to the cache kmalloc-128 of size 128
The buggy address is located 24 bytes inside of
freed 128-byte region [ffff8880742abb00, ffff8880742abb80)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x742ab
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000000 ffff88813ff24a00 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0xd2cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5932, tgid 5931 (syz.0.63), ts 80748630940
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1854
prep_new_page mm/page_alloc.c:1862 [inline]
get_page_from_freelist+0x220f/0x2280 mm/page_alloc.c:3933
__alloc_frozen_pages_noprof+0x1fc/0x400 mm/page_alloc.c:5471
alloc_slab_page mm/slub.c:3384 [inline]
allocate_slab+0x7d/0x5e0 mm/slub.c:3499
new_slab mm/slub.c:3550 [inline]
refill_objects+0x2d5/0x350 mm/slub.c:7539
refill_sheaf mm/slub.c:2917 [inline]
__pcs_replace_empty_main+0x2c8/0x6c0 mm/slub.c:4811
alloc_from_pcs mm/slub.c:4887 [inline]
slab_alloc_node mm/slub.c:5021 [inline]
__kmalloc_cache_noprof+0x396/0x600 mm/slub.c:5676
_kmalloc_noprof include/linux/slab.h:991 [inline]
_kzalloc_noprof include/linux/slab.h:1312 [inline]
dummy_alloc_request+0x7f/0x130 drivers/usb/gadget/udc/dummy_hcd.c:695
usb_ep_alloc_request+0x67/0x280 drivers/usb/gadget/udc/core.c:198
printer_req_alloc drivers/usb/gadget/function/f_printer.c:240 [inline]
printer_func_bind+0x265/0xbc0 drivers/usb/gadget/function/f_printer.c:1143
usb_add_function+0x2e1/0x9f0 drivers/usb/gadget/composite.c:333
configfs_composite_bind+0xde0/0x1410 drivers/usb/gadget/configfs.c:1802
gadget_bind_driver+0x2ca/0x9e0 drivers/usb/gadget/udc/core.c:1663
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x254/0xae0 drivers/base/dd.c:706
__driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868
driver_probe_device+0x4f/0x240 drivers/base/dd.c:898
page last free pid 16 tgid 16 ts 80343580851 stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
__free_pages_prepare mm/page_alloc.c:1401 [inline]
__free_frozen_pages+0xc97/0xd90 mm/page_alloc.c:2952
rcu_do_batch kernel/rcu/tree.c:2650 [inline]
rcu_core+0x926/0x1260 kernel/rcu/tree.c:2919
handle_softirqs+0x223/0x840 kernel/softirq.c:645
__do_softirq kernel/softirq.c:679 [inline]
invoke_softirq kernel/softirq.c:519 [inline]
__irq_exit_rcu+0xcb/0x220 kernel/softirq.c:758
irq_exit_rcu+0x9/0x30 kernel/softirq.c:775
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1062
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674
Memory state around the buggy address:
ffff8880742aba00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8880742aba80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880742abb00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff8880742abb80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880742abc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
This report is generated by a bot. It may contain errors.
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reply other threads:[~2026-10-09 2:07 UTC|newest]
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