[v6.1] KASAN: use-after-free Read in ep_open
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syzbot
Aug 14, 2026, 3:28:46 PM (3 days ago) Aug 14
to syzkaller...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: e4f7d8be268e Linux 6.1.182
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14f82949580000
kernel config: https://syzkaller.appspot.com/x/.config?x=31dfefc4a14efea3
dashboard link: https://syzkaller.appspot.com/bug?extid=7264e75089561d6b35df
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/156843a60452/disk-e4f7d8be.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/719d532a0151/vmlinux-e4f7d8be.xz
kernel image: https://storage.googleapis.com/syzbot-assets/12160bc2f9ec/bzImage-e4f7d8be.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7264e7...@syzkaller.appspotmail.com
gadgetfs: bound to dummy_udc driver
==================================================================
BUG: KASAN: use-after-free in __mutex_lock_common kernel/locking/mutex.c:582 [inline]
BUG: KASAN: use-after-free in __mutex_lock+0xf4/0xae0 kernel/locking/mutex.c:747
Read of size 8 at addr ffff888054be3460 by task syz.4.975/8502
CPU: 1 PID: 8502 Comm: syz.4.975 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
__mutex_lock_common kernel/locking/mutex.c:582 [inline]
__mutex_lock+0xf4/0xae0 kernel/locking/mutex.c:747
ep_open+0x4a/0x260 drivers/usb/gadget/legacy/inode.c:819
do_dentry_open+0x7dd/0x10b0 fs/open.c:882
do_open fs/namei.c:3634 [inline]
path_openat+0x2674/0x2f10 fs/namei.c:3791
do_filp_open+0x1ee/0x420 fs/namei.c:3818
do_sys_openat2+0x14b/0x4f0 fs/open.c:1320
do_sys_open fs/open.c:1336 [inline]
__do_sys_openat fs/open.c:1352 [inline]
__se_sys_openat fs/open.c:1347 [inline]
__x64_sys_openat+0x135/0x160 fs/open.c:1347
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: 0033:0x7f4c2e19e0d9
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:00007f4c2f0e3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f4c2e426270 RCX: 00007f4c2e19e0d9
RDX: 0000000000000002 RSI: 0000200000000600 RDI: ffffffffffffff9c
RBP: 00007f4c2e235024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4c2e426308 R14: 00007f4c2e426270 R15: 00007ffd1b6d6828
</TASK>
Allocated by task 8502:
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
kmalloc include/linux/slab.h:563 [inline]
kzalloc include/linux/slab.h:699 [inline]
activate_ep_files drivers/usb/gadget/legacy/inode.c:1596 [inline]
gadgetfs_bind+0x25b/0x820 drivers/usb/gadget/legacy/inode.c:1687
gadget_bind_driver+0x2af/0x760 drivers/usb/gadget/udc/core.c:1651
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
driver_probe_device+0x4f/0x420 drivers/base/dd.c:834
__driver_attach+0x43d/0x6c0 drivers/base/dd.c:1220
bus_for_each_dev+0x182/0x1f0 drivers/base/bus.c:303
bus_add_driver+0x324/0x5d0 drivers/base/bus.c:620
driver_register+0x32d/0x430 drivers/base/driver.c:246
usb_gadget_register_driver_owner+0xf5/0x260 drivers/usb/gadget/udc/core.c:1730
dev_config+0xe45/0x1260 drivers/usb/gadget/legacy/inode.c:1878
vfs_write+0x2dc/0x9a0 fs/read_write.c:582
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 8498:
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
destroy_ep_files+0x280/0x340 drivers/usb/gadget/legacy/inode.c:1571
gadgetfs_unbind+0x105/0x2a0 drivers/usb/gadget/legacy/inode.c:1650
gadget_unbind_driver+0x1bb/0x3d0 drivers/usb/gadget/udc/core.c:1702
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
driver_detach+0x1ef/0x2d0 drivers/base/dd.c:1368
bus_remove_driver+0x11c/0x230 drivers/base/bus.c:679
usb_gadget_unregister_driver+0x4a/0x70 drivers/usb/gadget/udc/core.c:1762
dev_release+0x82/0x1f0 drivers/usb/gadget/legacy/inode.c:1194
__fput+0x20a/0x8b0 fs/file_table.c:320
task_work_run+0x1d0/0x260 kernel/task_work.c:203
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
The buggy address belongs to the object at ffff888054be3400
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 96 bytes inside of
512-byte region [ffff888054be3400, ffff888054be3600)
The buggy address belongs to the physical page:
page:ffffea000152f800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x54be0
head:ffffea000152f800 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888017441c80
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd28c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4272, tgid 4272 (syz-executor), ts 74711631843, free_ts 23278782755
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_slab_page+0x5d/0x180 mm/slub.c:1799
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_track_caller+0xa0/0x240 mm/slab_common.c:956
kmalloc_reserve net/core/skbuff.c:446 [inline]
pskb_expand_head+0x1c0/0x13a0 net/core/skbuff.c:1849
netlink_trim+0x180/0x220 net/netlink/af_netlink.c:1299
netlink_broadcast+0x66/0x10f0 net/netlink/af_netlink.c:1505
nlmsg_multicast include/net/netlink.h:1078 [inline]
nlmsg_notify+0xe3/0x1a0 net/netlink/af_netlink.c:2559
fib_table_insert+0xd4e/0x1af0 net/ipv4/fib_trie.c:1385
fib_magic+0x2ca/0x3b0 net/ipv4/fib_frontend.c:1118
fib_add_ifaddr+0x135/0x5c0 net/ipv4/fib_frontend.c:1140
fib_inetaddr_event+0x13c/0x1c0 net/ipv4/fib_frontend.c:1454
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:
ffff888054be3300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888054be3380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888054be3400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888054be3480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888054be3500: fb 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.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
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If the report is a duplicate of another one, reply with:
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If you want to undo deduplication, reply with:
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syzbot found the following issue on:
HEAD commit: e4f7d8be268e Linux 6.1.182
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=14f82949580000
kernel config: https://syzkaller.appspot.com/x/.config?x=31dfefc4a14efea3
dashboard link: https://syzkaller.appspot.com/bug?extid=7264e75089561d6b35df
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/156843a60452/disk-e4f7d8be.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/719d532a0151/vmlinux-e4f7d8be.xz
kernel image: https://storage.googleapis.com/syzbot-assets/12160bc2f9ec/bzImage-e4f7d8be.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7264e7...@syzkaller.appspotmail.com
gadgetfs: bound to dummy_udc driver
==================================================================
BUG: KASAN: use-after-free in __mutex_lock_common kernel/locking/mutex.c:582 [inline]
BUG: KASAN: use-after-free in __mutex_lock+0xf4/0xae0 kernel/locking/mutex.c:747
Read of size 8 at addr ffff888054be3460 by task syz.4.975/8502
CPU: 1 PID: 8502 Comm: syz.4.975 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
__mutex_lock_common kernel/locking/mutex.c:582 [inline]
__mutex_lock+0xf4/0xae0 kernel/locking/mutex.c:747
ep_open+0x4a/0x260 drivers/usb/gadget/legacy/inode.c:819
do_dentry_open+0x7dd/0x10b0 fs/open.c:882
do_open fs/namei.c:3634 [inline]
path_openat+0x2674/0x2f10 fs/namei.c:3791
do_filp_open+0x1ee/0x420 fs/namei.c:3818
do_sys_openat2+0x14b/0x4f0 fs/open.c:1320
do_sys_open fs/open.c:1336 [inline]
__do_sys_openat fs/open.c:1352 [inline]
__se_sys_openat fs/open.c:1347 [inline]
__x64_sys_openat+0x135/0x160 fs/open.c:1347
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: 0033:0x7f4c2e19e0d9
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:00007f4c2f0e3028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f4c2e426270 RCX: 00007f4c2e19e0d9
RDX: 0000000000000002 RSI: 0000200000000600 RDI: ffffffffffffff9c
RBP: 00007f4c2e235024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f4c2e426308 R14: 00007f4c2e426270 R15: 00007ffd1b6d6828
</TASK>
Allocated by task 8502:
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
kmalloc include/linux/slab.h:563 [inline]
kzalloc include/linux/slab.h:699 [inline]
activate_ep_files drivers/usb/gadget/legacy/inode.c:1596 [inline]
gadgetfs_bind+0x25b/0x820 drivers/usb/gadget/legacy/inode.c:1687
gadget_bind_driver+0x2af/0x760 drivers/usb/gadget/udc/core.c:1651
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
driver_probe_device+0x4f/0x420 drivers/base/dd.c:834
__driver_attach+0x43d/0x6c0 drivers/base/dd.c:1220
bus_for_each_dev+0x182/0x1f0 drivers/base/bus.c:303
bus_add_driver+0x324/0x5d0 drivers/base/bus.c:620
driver_register+0x32d/0x430 drivers/base/driver.c:246
usb_gadget_register_driver_owner+0xf5/0x260 drivers/usb/gadget/udc/core.c:1730
dev_config+0xe45/0x1260 drivers/usb/gadget/legacy/inode.c:1878
vfs_write+0x2dc/0x9a0 fs/read_write.c:582
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 8498:
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
destroy_ep_files+0x280/0x340 drivers/usb/gadget/legacy/inode.c:1571
gadgetfs_unbind+0x105/0x2a0 drivers/usb/gadget/legacy/inode.c:1650
gadget_unbind_driver+0x1bb/0x3d0 drivers/usb/gadget/udc/core.c:1702
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
driver_detach+0x1ef/0x2d0 drivers/base/dd.c:1368
bus_remove_driver+0x11c/0x230 drivers/base/bus.c:679
usb_gadget_unregister_driver+0x4a/0x70 drivers/usb/gadget/udc/core.c:1762
dev_release+0x82/0x1f0 drivers/usb/gadget/legacy/inode.c:1194
__fput+0x20a/0x8b0 fs/file_table.c:320
task_work_run+0x1d0/0x260 kernel/task_work.c:203
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
The buggy address belongs to the object at ffff888054be3400
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 96 bytes inside of
512-byte region [ffff888054be3400, ffff888054be3600)
The buggy address belongs to the physical page:
page:ffffea000152f800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x54be0
head:ffffea000152f800 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 dead000000000100 dead000000000122 ffff888017441c80
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd28c0(GFP_NOWAIT|__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4272, tgid 4272 (syz-executor), ts 74711631843, free_ts 23278782755
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_slab_page+0x5d/0x180 mm/slub.c:1799
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_track_caller+0xa0/0x240 mm/slab_common.c:956
kmalloc_reserve net/core/skbuff.c:446 [inline]
pskb_expand_head+0x1c0/0x13a0 net/core/skbuff.c:1849
netlink_trim+0x180/0x220 net/netlink/af_netlink.c:1299
netlink_broadcast+0x66/0x10f0 net/netlink/af_netlink.c:1505
nlmsg_multicast include/net/netlink.h:1078 [inline]
nlmsg_notify+0xe3/0x1a0 net/netlink/af_netlink.c:2559
fib_table_insert+0xd4e/0x1af0 net/ipv4/fib_trie.c:1385
fib_magic+0x2ca/0x3b0 net/ipv4/fib_frontend.c:1118
fib_add_ifaddr+0x135/0x5c0 net/ipv4/fib_frontend.c:1140
fib_inetaddr_event+0x13c/0x1c0 net/ipv4/fib_frontend.c:1454
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:
ffff888054be3300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888054be3380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888054be3400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888054be3480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888054be3500: fb 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.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title
If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)
If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report
If you want to undo deduplication, reply with:
#syz undup
syzbot
Aug 15, 2026, 11:54:47 PM (2 days ago) Aug 15
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following issue on:
HEAD commit: e4f7d8be268e Linux 6.1.182
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11689a79580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1656c6c6580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/156843a60452/disk-e4f7d8be.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/719d532a0151/vmlinux-e4f7d8be.xz
kernel image: https://storage.googleapis.com/syzbot-assets/12160bc2f9ec/bzImage-e4f7d8be.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7264e7...@syzkaller.appspotmail.com
CPU: 1 PID: 4780 Comm: syz.3.310 Not tainted syzkaller #0
RAX: ffffffffffffffda RBX: 00007f820ba25fa0 RCX: 00007f820b79e0d9
</TASK>
Allocated by task 4776:
The buggy address belongs to the object at ffff888077560400
The buggy address belongs to the physical page:
page:ffffea0001dd5800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x77560
head:ffffea0001dd5800 order:2 compound_mapcount:0 compound_pincount:0
alloc_skb include/linux/skbuff.h:1303 [inline]
alloc_uevent_skb+0x7d/0x230 lib/kobject_uevent.c:290
uevent_net_broadcast_tagged lib/kobject_uevent.c:351 [inline]
kobject_uevent_net_broadcast+0x17e/0x530 lib/kobject_uevent.c:412
kobject_uevent_env+0x555/0x890 lib/kobject_uevent.c:608
rx_queue_add_kobject net/core/net-sysfs.c:1072 [inline]
net_rx_queue_update_kobjects+0x244/0x4d0 net/core/net-sysfs.c:1112
register_queue_kobjects net/core/net-sysfs.c:1772 [inline]
netdev_register_kobject+0x231/0x320 net/core/net-sysfs.c:2017
register_netdevice+0x133a/0x1b80 net/core/dev.c:10243
vxcan_newlink+0x553/0x670 drivers/net/can/vxcan.c:244
qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:306
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook+0x4b/0x490 mm/slab.h:737
slab_alloc_node mm/slub.c:3359 [inline]
kmem_cache_alloc_node+0x1ad/0x310 mm/slub.c:3404
__alloc_skb+0xf9/0x7d0 net/core/skbuff.c:505
alloc_skb include/linux/skbuff.h:1303 [inline]
netlink_alloc_large_skb net/netlink/af_netlink.c:1182 [inline]
netlink_sendmsg+0x654/0xbd0 net/netlink/af_netlink.c:1852
sock_sendmsg_nosec net/socket.c:718 [inline]
__sock_sendmsg net/socket.c:730 [inline]
__sys_sendto+0x497/0x650 net/socket.c:2153
__do_sys_sendto net/socket.c:2165 [inline]
__se_sys_sendto net/socket.c:2161 [inline]
__x64_sys_sendto+0xda/0xf0 net/socket.c:2161
ffff888077560380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888077560400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888077560480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888077560500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
HEAD commit: e4f7d8be268e Linux 6.1.182
git tree: linux-6.1.y
kernel config: https://syzkaller.appspot.com/x/.config?x=31dfefc4a14efea3
dashboard link: https://syzkaller.appspot.com/bug?extid=7264e75089561d6b35df
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=16887279580000
dashboard link: https://syzkaller.appspot.com/bug?extid=7264e75089561d6b35df
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1656c6c6580000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/156843a60452/disk-e4f7d8be.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/719d532a0151/vmlinux-e4f7d8be.xz
kernel image: https://storage.googleapis.com/syzbot-assets/12160bc2f9ec/bzImage-e4f7d8be.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7264e7...@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: use-after-free in __mutex_lock_common kernel/locking/mutex.c:582 [inline]
BUG: KASAN: use-after-free in __mutex_lock+0xf4/0xae0 kernel/locking/mutex.c:747
Read of size 8 at addr ffff888077560460 by task syz.3.310/4780
BUG: KASAN: use-after-free in __mutex_lock_common kernel/locking/mutex.c:582 [inline]
BUG: KASAN: use-after-free in __mutex_lock+0xf4/0xae0 kernel/locking/mutex.c:747
CPU: 1 PID: 4780 Comm: syz.3.310 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
__mutex_lock_common kernel/locking/mutex.c:582 [inline]
__mutex_lock+0xf4/0xae0 kernel/locking/mutex.c:747
ep_open+0x4a/0x260 drivers/usb/gadget/legacy/inode.c:819
do_dentry_open+0x7dd/0x10b0 fs/open.c:882
do_open fs/namei.c:3634 [inline]
path_openat+0x2674/0x2f10 fs/namei.c:3791
do_filp_open+0x1ee/0x420 fs/namei.c:3818
do_sys_openat2+0x14b/0x4f0 fs/open.c:1320
do_sys_open fs/open.c:1336 [inline]
__do_sys_openat fs/open.c:1352 [inline]
__se_sys_openat fs/open.c:1347 [inline]
__x64_sys_openat+0x135/0x160 fs/open.c:1347
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: 0033:0x7f820b79e0d9
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
__mutex_lock_common kernel/locking/mutex.c:582 [inline]
__mutex_lock+0xf4/0xae0 kernel/locking/mutex.c:747
ep_open+0x4a/0x260 drivers/usb/gadget/legacy/inode.c:819
do_dentry_open+0x7dd/0x10b0 fs/open.c:882
do_open fs/namei.c:3634 [inline]
path_openat+0x2674/0x2f10 fs/namei.c:3791
do_filp_open+0x1ee/0x420 fs/namei.c:3818
do_sys_openat2+0x14b/0x4f0 fs/open.c:1320
do_sys_open fs/open.c:1336 [inline]
__do_sys_openat fs/open.c:1352 [inline]
__se_sys_openat fs/open.c:1347 [inline]
__x64_sys_openat+0x135/0x160 fs/open.c:1347
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
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:00007ffd7ca989c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f820ba25fa0 RCX: 00007f820b79e0d9
RDX: 0000000000000002 RSI: 0000200000000600 RDI: ffffffffffffff9c
RBP: 00007f820b835024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f820ba25fac R14: 00007f820ba25fa0 R15: 00007f820ba25fa0
</TASK>
Allocated by task 4776:
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
kmalloc include/linux/slab.h:563 [inline]
kzalloc include/linux/slab.h:699 [inline]
activate_ep_files drivers/usb/gadget/legacy/inode.c:1596 [inline]
gadgetfs_bind+0x25b/0x820 drivers/usb/gadget/legacy/inode.c:1687
gadget_bind_driver+0x2af/0x760 drivers/usb/gadget/udc/core.c:1651
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
driver_probe_device+0x4f/0x420 drivers/base/dd.c:834
__driver_attach+0x43d/0x6c0 drivers/base/dd.c:1220
bus_for_each_dev+0x182/0x1f0 drivers/base/bus.c:303
bus_add_driver+0x324/0x5d0 drivers/base/bus.c:620
driver_register+0x32d/0x430 drivers/base/driver.c:246
usb_gadget_register_driver_owner+0xf5/0x260 drivers/usb/gadget/udc/core.c:1730
dev_config+0xe45/0x1260 drivers/usb/gadget/legacy/inode.c:1878
vfs_write+0x2dc/0x9a0 fs/read_write.c:582
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 4776:
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
kmalloc include/linux/slab.h:563 [inline]
kzalloc include/linux/slab.h:699 [inline]
activate_ep_files drivers/usb/gadget/legacy/inode.c:1596 [inline]
gadgetfs_bind+0x25b/0x820 drivers/usb/gadget/legacy/inode.c:1687
gadget_bind_driver+0x2af/0x760 drivers/usb/gadget/udc/core.c:1651
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
driver_probe_device+0x4f/0x420 drivers/base/dd.c:834
__driver_attach+0x43d/0x6c0 drivers/base/dd.c:1220
bus_for_each_dev+0x182/0x1f0 drivers/base/bus.c:303
bus_add_driver+0x324/0x5d0 drivers/base/bus.c:620
driver_register+0x32d/0x430 drivers/base/driver.c:246
usb_gadget_register_driver_owner+0xf5/0x260 drivers/usb/gadget/udc/core.c:1730
dev_config+0xe45/0x1260 drivers/usb/gadget/legacy/inode.c:1878
vfs_write+0x2dc/0x9a0 fs/read_write.c:582
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
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 96 bytes inside of
512-byte region [ffff888077560400, ffff888077560600)
The buggy address is located 96 bytes inside of
The buggy address belongs to the physical page:
head:ffffea0001dd5800 order:2 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000001 ffff888017441c80
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 4395, tgid 4395 (syz-executor), ts 91073498086, free_ts 88791479158
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
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_slab_page+0x5d/0x180 mm/slub.c:1799
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_track_caller+0xa0/0x240 mm/slab_common.c:956
kmalloc_reserve net/core/skbuff.c:446 [inline]
__alloc_skb+0x226/0x7d0 net/core/skbuff.c:515
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_slab_page+0x5d/0x180 mm/slub.c:1799
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_track_caller+0xa0/0x240 mm/slab_common.c:956
kmalloc_reserve net/core/skbuff.c:446 [inline]
alloc_skb include/linux/skbuff.h:1303 [inline]
alloc_uevent_skb+0x7d/0x230 lib/kobject_uevent.c:290
uevent_net_broadcast_tagged lib/kobject_uevent.c:351 [inline]
kobject_uevent_net_broadcast+0x17e/0x530 lib/kobject_uevent.c:412
kobject_uevent_env+0x555/0x890 lib/kobject_uevent.c:608
rx_queue_add_kobject net/core/net-sysfs.c:1072 [inline]
net_rx_queue_update_kobjects+0x244/0x4d0 net/core/net-sysfs.c:1112
register_queue_kobjects net/core/net-sysfs.c:1772 [inline]
netdev_register_kobject+0x231/0x320 net/core/net-sysfs.c:2017
register_netdevice+0x133a/0x1b80 net/core/dev.c:10243
vxcan_newlink+0x553/0x670 drivers/net/can/vxcan.c:244
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
qlink_free mm/kasan/quarantine.c:168 [inline]
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
qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:306
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook+0x4b/0x490 mm/slab.h:737
slab_alloc_node mm/slub.c:3359 [inline]
kmem_cache_alloc_node+0x1ad/0x310 mm/slub.c:3404
__alloc_skb+0xf9/0x7d0 net/core/skbuff.c:505
alloc_skb include/linux/skbuff.h:1303 [inline]
netlink_alloc_large_skb net/netlink/af_netlink.c:1182 [inline]
netlink_sendmsg+0x654/0xbd0 net/netlink/af_netlink.c:1852
sock_sendmsg_nosec net/socket.c:718 [inline]
__sock_sendmsg net/socket.c:730 [inline]
__sys_sendto+0x497/0x650 net/socket.c:2153
__do_sys_sendto net/socket.c:2165 [inline]
__se_sys_sendto net/socket.c:2161 [inline]
__x64_sys_sendto+0xda/0xf0 net/socket.c:2161
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
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
Memory state around the buggy address:
ffff888077560300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888077560380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888077560400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888077560480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888077560500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.
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