[v6.1] KASAN: use-after-free Read in raw_process_ep_io

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fb28aa725e05 Linux 6.1.180
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14c1ec9e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=31dfefc4a14efea3
dashboard link: https://syzkaller.appspot.com/bug?extid=7f18d6ec1645063a871d
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=165a43b9580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15e12649580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9a6fe2a54d0f/disk-fb28aa72.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/742b23a1d931/vmlinux-fb28aa72.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b3f257c16d2e/bzImage-fb28aa72.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7f18d6...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in string_nocheck lib/vsprintf.c:643 [inline]
BUG: KASAN: use-after-free in string+0x204/0x290 lib/vsprintf.c:725
Read of size 1 at addr ffff8880590f7ca0 by task syz.0.110/4586

CPU: 1 PID: 4586 Comm: syz.0.110 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<TASK>
dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
print_address_description mm/kasan/report.c:316 [inline]
print_report+0xa8/0x210 mm/kasan/report.c:420
kasan_report+0x10b/0x140 mm/kasan/report.c:524
string_nocheck lib/vsprintf.c:643 [inline]
string+0x204/0x290 lib/vsprintf.c:725
vsnprintf+0x10db/0x1c20 lib/vsprintf.c:2805
snprintf+0xe5/0x140 lib/vsprintf.c:2940
set_dev_info drivers/base/core.c:4936 [inline]
dev_vprintk_emit+0x303/0x3de drivers/base/core.c:4946
dev_printk_emit+0xeb/0x139 drivers/base/core.c:4959
_dev_err+0x11b/0x16c drivers/base/core.c:5014
raw_process_ep_io+0x7e8/0xc80 drivers/usb/gadget/legacy/raw_gadget.c:1070
raw_ioctl_ep_write drivers/usb/gadget/legacy/raw_gadget.c:1108 [inline]
raw_ioctl+0x2417/0x3cd0 drivers/usb/gadget/legacy/raw_gadget.c:1280
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfa/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6d9f39dcab
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007ffd881bc4a0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f6d9f39dcab
RDX: 00007ffd881bc520 RSI: 0000000040085507 RDI: 0000000000000003
RBP: 0000000000000003 R08: 00007f6d9f750320 R09: 0000000000000000
R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000a R14: 00007f6d9f625fa0 R15: 00007f6d9f625fa0
</TASK>

Allocated by task 4585:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
____kasan_kmalloc mm/kasan/common.c:375 [inline]
__kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slab_common.c:936 [inline]
__kmalloc_node_track_caller+0xb0/0x240 mm/slab_common.c:956
kvasprintf+0xe8/0x1a0 lib/kasprintf.c:25
kobject_set_name_vargs+0x5d/0x110 lib/kobject.c:265
dev_set_name+0xdf/0x130 drivers/base/core.c:3485
usb_add_gadget+0x474/0x6f0 drivers/usb/gadget/udc/core.c:1448
usb_add_gadget_udc_release+0x198/0x1e0 drivers/usb/gadget/udc/core.c:1506
dummy_udc_probe+0x686/0x780 drivers/usb/gadget/udc/dummy_hcd.c:1102
platform_probe+0x137/0x1c0 drivers/base/platform.c:1400
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x24a/0xb40 drivers/base/dd.c:638
__driver_probe_device+0x1f5/0x390 drivers/base/dd.c:804
device_driver_attach+0xd9/0x1c0 drivers/base/dd.c:1131
bind_store+0x33b/0x380 drivers/base/bus.c:216
kernfs_fop_write_iter+0x3a0/0x520 fs/kernfs/file.c:352
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x482/0x9a0 fs/read_write.c:584
ksys_write+0x14d/0x260 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2

Freed by task 4587:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
kasan_slab_free include/linux/kasan.h:177 [inline]
slab_free_hook mm/slub.c:1729 [inline]
slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1755
slab_free mm/slub.c:3687 [inline]
__kmem_cache_free+0xb6/0x200 mm/slub.c:3700
kobject_cleanup lib/kobject.c:687 [inline]
kobject_release lib/kobject.c:712 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x25c/0x450 lib/kobject.c:729
dummy_udc_remove+0x54/0x60 drivers/usb/gadget/udc/dummy_hcd.c:1123
platform_remove+0x92/0xe0 drivers/base/platform.c:1422
device_remove drivers/base/dd.c:547 [inline]
__device_release_driver drivers/base/dd.c:1279 [inline]
device_release_driver_internal+0x47d/0x7c0 drivers/base/dd.c:1305
unbind_store+0x2e2/0x300 drivers/base/bus.c:193
kernfs_fop_write_iter+0x3a0/0x520 fs/kernfs/file.c:352
call_write_iter include/linux/fs.h:2265 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x482/0x9a0 fs/read_write.c:584
ksys_write+0x14d/0x260 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff8880590f7ca0
which belongs to the cache kmalloc-16 of size 16
The buggy address is located 0 bytes inside of
16-byte region [ffff8880590f7ca0, ffff8880590f7cb0)

The buggy address belongs to the physical page:
page:ffffea0001643dc0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x590f7
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 dead000000000100 dead000000000122 ffff8880174413c0
raw: 0000000000000000 0000000000800080 00000001ffffffff 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 0x112cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY), pid 4330, tgid 4330 (syz-executor), ts 87662239838, free_ts 25365765421
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2560
prep_new_page mm/page_alloc.c:2567 [inline]
get_page_from_freelist+0x206b/0x2180 mm/page_alloc.c:4358
__alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5658
__alloc_pages_node include/linux/gfp.h:237 [inline]
alloc_slab_page+0x4f/0x180 mm/slub.c:1801
allocate_slab mm/slub.c:1944 [inline]
new_slab+0x87/0x2d0 mm/slub.c:1997
___slab_alloc+0xbc5/0x1240 mm/slub.c:3154
__slab_alloc mm/slub.c:3240 [inline]
slab_alloc_node mm/slub.c:3325 [inline]
__kmem_cache_alloc_node+0x126/0x270 mm/slub.c:3398
__do_kmalloc_node mm/slab_common.c:935 [inline]
__kmalloc_node+0xa2/0x240 mm/slab_common.c:943
kmalloc_node include/linux/slab.h:589 [inline]
kvmalloc_node+0x6c/0x180 mm/util.c:581
xt_jumpstack_alloc net/netfilter/x_tables.c:1377 [inline]
xt_replace_table+0x176/0x790 net/netfilter/x_tables.c:1416
xt_register_table+0x151/0x450 net/netfilter/x_tables.c:1502
arpt_register_table+0x171/0x690 net/ipv4/netfilter/arp_tables.c:1543
arptable_filter_table_init+0x3d/0x60 net/ipv4/netfilter/arptable_filter.c:39
xt_find_table_lock+0x220/0x360 net/netfilter/x_tables.c:1282
xt_request_find_table_lock+0x22/0x100 net/netfilter/x_tables.c:1307
get_info net/ipv4/netfilter/arp_tables.c:818 [inline]
do_arpt_get_ctl+0x686/0x10a0 net/ipv4/netfilter/arp_tables.c:1461
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1487 [inline]
free_pcp_prepare mm/page_alloc.c:1537 [inline]
free_unref_page_prepare+0x8e5/0x9e0 mm/page_alloc.c:3414
free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3509
free_contig_range+0x9d/0x150 mm/page_alloc.c:9626
destroy_args+0xef/0xa0e mm/debug_vm_pgtable.c:1031
debug_vm_pgtable+0x33c/0x38e mm/debug_vm_pgtable.c:1359
do_one_initcall+0x257/0x800 init/main.c:1309
do_initcall_level+0x13d/0x1ed init/main.c:1382
do_initcalls+0x4b/0x8a init/main.c:1398
kernel_init_freeable+0x401/0x5ab init/main.c:1637
kernel_init+0x19/0x1b0 init/main.c:1525
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Memory state around the buggy address:
ffff8880590f7b80: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc
ffff8880590f7c00: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc
>ffff8880590f7c80: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc
^
ffff8880590f7d00: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc
ffff8880590f7d80: fa fb fc fc fa fb fc fc fa fb fc fc fa fb fc fc
==================================================================


---
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