[moderation] [usb?] KASAN: slab-use-after-free Read in usbtmc_read_bulk_cb

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c03e9c42ae8f Merge tag 'dma-mapping-6.19-2026-01-20' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10767852580000
kernel config: https://syzkaller.appspot.com/x/.config?x=312c0a6c03e6d7df
dashboard link: https://syzkaller.appspot.com/bug?extid=8b78b2f208234fbb75f6
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
userspace arch: i386
CC: [gre...@linuxfoundation.org linux-...@vger.kernel.org linu...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/49ff533e4446/disk-c03e9c42.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b6020552e575/vmlinux-c03e9c42.xz
kernel image: https://storage.googleapis.com/syzbot-assets/228665ff0b0d/bzImage-c03e9c42.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8b78b2...@syzkaller.appspotmail.com

usbtmc 3-1:16.0: usbtmc_read_bulk_cb - nonzero read bulk status received: -71
usbtmc 3-1:16.0: usbtmc_read_bulk_cb - nonzero read bulk status received: -71
usbtmc 3-1:16.0: usbtmc_read_bulk_cb - nonzero read bulk status received: -71
==================================================================
BUG: KASAN: slab-use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:162
Read of size 1 at addr ffff88802a3a7848 by task swapper/0/0

CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026
Call Trace:
<IRQ>
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
__kasan_check_byte+0x2a/0x40 mm/kasan/common.c:574
kasan_check_byte include/linux/kasan.h:402 [inline]
lock_acquire+0x84/0x330 kernel/locking/lockdep.c:5842
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:162
usbtmc_read_bulk_cb+0xc9/0x440 drivers/usb/class/usbtmc.c:791
__usb_hcd_giveback_urb+0x376/0x540 drivers/usb/core/hcd.c:1661
dummy_timer+0xbbd/0x45d0 drivers/usb/gadget/udc/dummy_hcd.c:1995
__run_hrtimer kernel/time/hrtimer.c:1777 [inline]
__hrtimer_run_queues+0x527/0xc30 kernel/time/hrtimer.c:1841
hrtimer_run_softirq+0x187/0x2b0 kernel/time/hrtimer.c:1858
handle_softirqs+0x22a/0x7c0 kernel/softirq.c:622
__do_softirq kernel/softirq.c:656 [inline]
invoke_softirq kernel/softirq.c:496 [inline]
__irq_exit_rcu+0x5f/0x150 kernel/softirq.c:723
irq_exit_rcu+0x9/0x30 kernel/softirq.c:739
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1056 [inline]
sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1056
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0010:finish_task_switch+0x241/0x920 kernel/sched/core.c:5118
Code: 0f 84 bd 01 00 00 48 85 db 0f 85 e4 01 00 00 0f 1f 44 00 00 4c 8b 75 d0 4c 89 e7 e8 f9 42 e8 09 e8 74 96 37 00 fb 4c 8b 65 c0 <49> 8d bc 24 48 16 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0000:ffffffff8e007b58 EFLAGS: 00000202
RAX: 0000000000280a2f RBX: 0000000000000000 RCX: 0000000080000001
RDX: 0000000000000000 RSI: ffffffff8dacf6b8 RDI: ffffffff8be73680
RBP: ffffffff8e007bb0 R08: ffffffff8fced477 R09: 1ffffffff1f9da8e
R10: dffffc0000000000 R11: fffffbfff1f9da8f R12: ffffffff8e0953c0
R13: dffffc0000000000 R14: ffff888033949e80 R15: ffff8880b863b498
context_switch kernel/sched/core.c:5263 [inline]
__schedule+0x14f7/0x4fb0 kernel/sched/core.c:6867
schedule_idle+0x51/0x90 kernel/sched/core.c:6990
do_idle+0x499/0x500 kernel/sched/idle.c:360
cpu_startup_entry+0x43/0x60 kernel/sched/idle.c:430
rest_init+0x2de/0x300 init/main.c:757
start_kernel+0x380/0x3d0 init/main.c:1206
x86_64_start_reservations+0x24/0x30 arch/x86/kernel/head64.c:310
x86_64_start_kernel+0x143/0x1c0 arch/x86/kernel/head64.c:291
common_startup_64+0x13e/0x147
</TASK>

Allocated by task 10641:
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:398 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__kmalloc_cache_noprof+0x3d1/0x6e0 mm/slub.c:5776
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
usbtmc_open+0x9c/0x8e0 drivers/usb/class/usbtmc.c:175
usb_open+0x156/0x1e0 drivers/usb/core/file.c:47
chrdev_open+0x4cd/0x5e0 fs/char_dev.c:414
do_dentry_open+0x7ce/0x1420 fs/open.c:962
vfs_open+0x3b/0x340 fs/open.c:1094
do_open fs/namei.c:4637 [inline]
path_openat+0x3486/0x3e20 fs/namei.c:4796
do_filp_open+0x22d/0x490 fs/namei.c:4823
do_sys_openat2+0x12f/0x220 fs/open.c:1430
do_sys_open fs/open.c:1436 [inline]
__do_compat_sys_openat fs/open.c:1498 [inline]
__se_compat_sys_openat fs/open.c:1496 [inline]
__ia32_compat_sys_openat+0x131/0x160 fs/open.c:1496
do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
do_int80_emulation+0x111/0x400 arch/x86/entry/syscall_32.c:172
asm_int80_emulation+0x1a/0x20 arch/x86/include/asm/idtentry.h:621

Freed by task 10643:
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2540 [inline]
slab_free mm/slub.c:6670 [inline]
kfree+0x1be/0x650 mm/slub.c:6878
usbtmc_release+0x246/0x280 drivers/usb/class/usbtmc.c:261
__fput+0x44f/0xa70 fs/file_table.c:468
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:44 [inline]
exit_to_user_mode_loop+0xed/0x480 kernel/entry/common.c:75
__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_work include/linux/entry-common.h:159 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
__do_fast_syscall_32+0x38e/0x540 arch/x86/entry/syscall_32.c:310
do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:332
entry_SYSENTER_compat_after_hwframe+0x84/0x8e

The buggy address belongs to the object at ffff88802a3a7800
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 72 bytes inside of
freed 1024-byte region [ffff88802a3a7800, ffff88802a3a7c00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2a3a0
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 ffff88813ff26dc0 ffffea0000bcda00 dead000000000002
raw: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813ff26dc0 ffffea0000bcda00 dead000000000002
head: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0000a8e801 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 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1955, tgid 1955 (kworker/u8:7), ts 93840666180, free_ts 93779664948
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x228/0x280 mm/page_alloc.c:1884
prep_new_page mm/page_alloc.c:1892 [inline]
get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3945
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5240
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2486
alloc_slab_page mm/slub.c:3075 [inline]
allocate_slab+0x86/0x3a0 mm/slub.c:3248
new_slab mm/slub.c:3302 [inline]
___slab_alloc+0xd82/0x1760 mm/slub.c:4656
__slab_alloc+0x65/0x100 mm/slub.c:4779
__slab_alloc_node mm/slub.c:4855 [inline]
slab_alloc_node mm/slub.c:5251 [inline]
__do_kmalloc_node mm/slub.c:5656 [inline]
__kmalloc_noprof+0x46c/0x7e0 mm/slub.c:5669
kmalloc_noprof include/linux/slab.h:961 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
ieee802_11_parse_elems_full+0x159/0x2ab0 net/mac80211/parse.c:1031
ieee802_11_parse_elems net/mac80211/ieee80211_i.h:2469 [inline]
ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1571 [inline]
ieee80211_ibss_rx_queued_mgmt+0x4ca/0x2c80 net/mac80211/ibss.c:1602
ieee80211_iface_process_skb net/mac80211/iface.c:1736 [inline]
ieee80211_iface_work+0x85e/0x12b0 net/mac80211/iface.c:1790
cfg80211_wiphy_work+0x2ab/0x450 net/wireless/core.c:438
process_one_work kernel/workqueue.c:3257 [inline]
process_scheduled_works+0xaec/0x17a0 kernel/workqueue.c:3340
worker_thread+0x89f/0xd90 kernel/workqueue.c:3421
kthread+0x726/0x8b0 kernel/kthread.c:463
ret_from_fork+0x51b/0xa40 arch/x86/kernel/process.c:158
page last free pid 5188 tgid 5188 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1433 [inline]
__free_frozen_pages+0xbb0/0xd10 mm/page_alloc.c:2973
discard_slab mm/slub.c:3346 [inline]
__put_partials+0x146/0x170 mm/slub.c:3886
__slab_free+0x294/0x320 mm/slub.c:5952
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x97/0x100 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4953 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
kmem_cache_alloc_node_noprof+0x427/0x6f0 mm/slub.c:5315
__alloc_skb+0x1d7/0x390 net/core/skbuff.c:679
alloc_skb include/linux/skbuff.h:1383 [inline]
alloc_skb_with_frags+0xca/0x890 net/core/skbuff.c:6714
sock_alloc_send_pskb+0x878/0x990 net/core/sock.c:2995
unix_dgram_sendmsg+0x44e/0x17b0 net/unix/af_unix.c:2130
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg+0x21c/0x270 net/socket.c:742
__sys_sendto+0x3c0/0x550 net/socket.c:2206
__do_sys_sendto net/socket.c:2213 [inline]
__se_sys_sendto net/socket.c:2209 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2209
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff88802a3a7700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88802a3a7780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802a3a7800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802a3a7880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802a3a7900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 0f 84 bd 01 00 00 je 0x1c3
6: 48 85 db test %rbx,%rbx
9: 0f 85 e4 01 00 00 jne 0x1f3
f: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
14: 4c 8b 75 d0 mov -0x30(%rbp),%r14
18: 4c 89 e7 mov %r12,%rdi
1b: e8 f9 42 e8 09 call 0x9e84319
20: e8 74 96 37 00 call 0x379699
25: fb sti
26: 4c 8b 65 c0 mov -0x40(%rbp),%r12
* 2a: 49 8d bc 24 48 16 00 lea 0x1648(%r12),%rdi <-- trapping instruction
31: 00
32: 48 89 f8 mov %rdi,%rax
35: 48 c1 e8 03 shr $0x3,%rax
39: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax
3e: 84 c0 test %al,%al


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