[moderation] [fs?] KASAN: slab-use-after-free Read in bus_remove_driver
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syzbot
Jul 9, 2025, 9:59:31 AMJul 9
to syzkaller-upst...@googlegroups.com
Hello,
syzbot found the following issue on:
HEAD commit: 26ffb3d6f02c Add linux-next specific files for 20250704
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15f82f70580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1e4f88512ae53408
dashboard link: https://syzkaller.appspot.com/bug?extid=1e1f9de12b2231befdaa
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
CC: [da...@kernel.org gre...@linuxfoundation.org linux-...@vger.kernel.org linux-...@vger.kernel.org raf...@kernel.org]
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fd5569903143/disk-26ffb3d6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1b0c9505c543/vmlinux-26ffb3d6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9d864c72bed1/bzImage-26ffb3d6.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1e1f9d...@syzkaller.appspotmail.com
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f9b4bdb5fa0 R15: 00007ffc9b6ea518
</TASK>
comedi comedi1: c6xdigio: I/O port conflict (0x8001,3)
==================================================================
BUG: KASAN: slab-use-after-free in sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:522
Read of size 8 at addr ffff888146a88630 by task syz.2.940/11029
CPU: 1 UID: 0 PID: 11029 Comm: syz.2.940 Not tainted 6.16.0-rc4-next-20250704-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:408 [inline]
print_report+0xd2/0x2b0 mm/kasan/report.c:521
kasan_report+0x118/0x150 mm/kasan/report.c:634
sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:522
remove_bind_files drivers/base/bus.c:605 [inline]
bus_remove_driver+0x198/0x2f0 drivers/base/bus.c:743
comedi_device_detach+0x134/0x720 drivers/comedi/drivers.c:207
comedi_device_attach+0x568/0x670 drivers/comedi/drivers.c:1000
do_devconfig_ioctl drivers/comedi/comedi_fops.c:855 [inline]
comedi_unlocked_ioctl+0x686/0xf40 drivers/comedi/comedi_fops.c:2136
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9b4bb8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9b4c9ec038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f9b4bdb5fa0 RCX: 00007f9b4bb8e929
RDX: 0000200000000100 RSI: 0000000040946400 RDI: 0000000000000003
RBP: 00007f9b4c9ec090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f9b4bdb5fa0 R15: 00007ffc9b6ea518
</TASK>
Allocated by task 11011:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
kasan_kmalloc include/linux/kasan.h:260 [inline]
__kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4396
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
bus_add_driver+0x162/0x640 drivers/base/bus.c:662
driver_register+0x23a/0x320 drivers/base/driver.c:249
c6xdigio_attach+0x94/0x890 drivers/comedi/drivers/c6xdigio.c:253
comedi_device_attach+0x520/0x670 drivers/comedi/drivers.c:996
do_devconfig_ioctl drivers/comedi/comedi_fops.c:855 [inline]
comedi_unlocked_ioctl+0x686/0xf40 drivers/comedi/comedi_fops.c:2136
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 11013:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:247 [inline]
__kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2417 [inline]
slab_free mm/slub.c:4680 [inline]
kfree+0x18e/0x440 mm/slub.c:4879
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x22b/0x480 lib/kobject.c:737
bus_remove_driver+0x245/0x2f0 drivers/base/bus.c:749
comedi_device_detach+0x134/0x720 drivers/comedi/drivers.c:207
do_devconfig_ioctl drivers/comedi/comedi_fops.c:833 [inline]
comedi_unlocked_ioctl+0xc4b/0xf40 drivers/comedi/comedi_fops.c:2136
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888146a88600
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 48 bytes inside of
freed 256-byte region [ffff888146a88600, ffff888146a88700)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x146a88
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88801a441b40 ffffea0001dbe880 dead000000000006
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff88801a441b40 ffffea0001dbe880 dead000000000006
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 057ff00000000001 ffffea00051aa201 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 13106412839, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1848
prep_new_page mm/page_alloc.c:1856 [inline]
get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3855
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5145
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
alloc_slab_page mm/slub.c:2487 [inline]
allocate_slab+0x8a/0x370 mm/slub.c:2655
new_slab mm/slub.c:2709 [inline]
___slab_alloc+0xbeb/0x1410 mm/slub.c:3891
__slab_alloc mm/slub.c:3981 [inline]
__slab_alloc_node mm/slub.c:4056 [inline]
slab_alloc_node mm/slub.c:4217 [inline]
__kmalloc_cache_noprof+0x296/0x3d0 mm/slub.c:4391
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
bus_add_driver+0x162/0x640 drivers/base/bus.c:662
driver_register+0x23a/0x320 drivers/base/driver.c:249
usb_register_driver+0x1e4/0x390 drivers/usb/core/driver.c:1078
__usb_serial_register_drivers+0x204/0xc80 drivers/usb/serial/usb-serial.c:1505
do_one_initcall+0x233/0x820 init/main.c:1269
do_initcall_level+0x137/0x1f0 init/main.c:1331
do_initcalls+0x69/0xd0 init/main.c:1347
kernel_init_freeable+0x3d9/0x570 init/main.c:1579
kernel_init+0x1d/0x1d0 init/main.c:1469
page_owner free stack trace missing
Memory state around the buggy address:
ffff888146a88500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888146a88580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888146a88600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888146a88680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888146a88700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
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 found the following issue on:
HEAD commit: 26ffb3d6f02c Add linux-next specific files for 20250704
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15f82f70580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1e4f88512ae53408
dashboard link: https://syzkaller.appspot.com/bug?extid=1e1f9de12b2231befdaa
compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7
CC: [da...@kernel.org gre...@linuxfoundation.org linux-...@vger.kernel.org linux-...@vger.kernel.org raf...@kernel.org]
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/fd5569903143/disk-26ffb3d6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1b0c9505c543/vmlinux-26ffb3d6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9d864c72bed1/bzImage-26ffb3d6.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1e1f9d...@syzkaller.appspotmail.com
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f9b4bdb5fa0 R15: 00007ffc9b6ea518
</TASK>
comedi comedi1: c6xdigio: I/O port conflict (0x8001,3)
==================================================================
BUG: KASAN: slab-use-after-free in sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:522
Read of size 8 at addr ffff888146a88630 by task syz.2.940/11029
CPU: 1 UID: 0 PID: 11029 Comm: syz.2.940 Not tainted 6.16.0-rc4-next-20250704-syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:408 [inline]
print_report+0xd2/0x2b0 mm/kasan/report.c:521
kasan_report+0x118/0x150 mm/kasan/report.c:634
sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:522
remove_bind_files drivers/base/bus.c:605 [inline]
bus_remove_driver+0x198/0x2f0 drivers/base/bus.c:743
comedi_device_detach+0x134/0x720 drivers/comedi/drivers.c:207
comedi_device_attach+0x568/0x670 drivers/comedi/drivers.c:1000
do_devconfig_ioctl drivers/comedi/comedi_fops.c:855 [inline]
comedi_unlocked_ioctl+0x686/0xf40 drivers/comedi/comedi_fops.c:2136
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9b4bb8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9b4c9ec038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f9b4bdb5fa0 RCX: 00007f9b4bb8e929
RDX: 0000200000000100 RSI: 0000000040946400 RDI: 0000000000000003
RBP: 00007f9b4c9ec090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000000 R14: 00007f9b4bdb5fa0 R15: 00007ffc9b6ea518
</TASK>
Allocated by task 11011:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:377 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:394
kasan_kmalloc include/linux/kasan.h:260 [inline]
__kmalloc_cache_noprof+0x230/0x3d0 mm/slub.c:4396
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
bus_add_driver+0x162/0x640 drivers/base/bus.c:662
driver_register+0x23a/0x320 drivers/base/driver.c:249
c6xdigio_attach+0x94/0x890 drivers/comedi/drivers/c6xdigio.c:253
comedi_device_attach+0x520/0x670 drivers/comedi/drivers.c:996
do_devconfig_ioctl drivers/comedi/comedi_fops.c:855 [inline]
comedi_unlocked_ioctl+0x686/0xf40 drivers/comedi/comedi_fops.c:2136
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 11013:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:247 [inline]
__kasan_slab_free+0x62/0x70 mm/kasan/common.c:264
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2417 [inline]
slab_free mm/slub.c:4680 [inline]
kfree+0x18e/0x440 mm/slub.c:4879
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x22b/0x480 lib/kobject.c:737
bus_remove_driver+0x245/0x2f0 drivers/base/bus.c:749
comedi_device_detach+0x134/0x720 drivers/comedi/drivers.c:207
do_devconfig_ioctl drivers/comedi/comedi_fops.c:833 [inline]
comedi_unlocked_ioctl+0xc4b/0xf40 drivers/comedi/comedi_fops.c:2136
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xf9/0x170 fs/ioctl.c:584
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff888146a88600
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 48 bytes inside of
freed 256-byte region [ffff888146a88600, ffff888146a88700)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x146a88
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88801a441b40 ffffea0001dbe880 dead000000000006
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff88801a441b40 ffffea0001dbe880 dead000000000006
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 057ff00000000001 ffffea00051aa201 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 13106412839, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1848
prep_new_page mm/page_alloc.c:1856 [inline]
get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3855
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5145
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
alloc_slab_page mm/slub.c:2487 [inline]
allocate_slab+0x8a/0x370 mm/slub.c:2655
new_slab mm/slub.c:2709 [inline]
___slab_alloc+0xbeb/0x1410 mm/slub.c:3891
__slab_alloc mm/slub.c:3981 [inline]
__slab_alloc_node mm/slub.c:4056 [inline]
slab_alloc_node mm/slub.c:4217 [inline]
__kmalloc_cache_noprof+0x296/0x3d0 mm/slub.c:4391
kmalloc_noprof include/linux/slab.h:905 [inline]
kzalloc_noprof include/linux/slab.h:1039 [inline]
bus_add_driver+0x162/0x640 drivers/base/bus.c:662
driver_register+0x23a/0x320 drivers/base/driver.c:249
usb_register_driver+0x1e4/0x390 drivers/usb/core/driver.c:1078
__usb_serial_register_drivers+0x204/0xc80 drivers/usb/serial/usb-serial.c:1505
do_one_initcall+0x233/0x820 init/main.c:1269
do_initcall_level+0x137/0x1f0 init/main.c:1331
do_initcalls+0x69/0xd0 init/main.c:1347
kernel_init_freeable+0x3d9/0x570 init/main.c:1579
kernel_init+0x1d/0x1d0 init/main.c:1469
page_owner free stack trace missing
Memory state around the buggy address:
ffff888146a88500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888146a88580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888146a88600: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888146a88680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888146a88700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
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
Sep 24, 2025, 2:30:28 AM (2 days ago) Sep 24
to syzkaller-upst...@googlegroups.com
syzbot has found a reproducer for the following issue on:
HEAD commit: ce7f1a983b07 Add linux-next specific files for 20250923
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=170b8d34580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1be6fa3d47bce66e
dashboard link: https://syzkaller.appspot.com/bug?extid=1e1f9de12b2231befdaa
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13fe94e2580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11912142580000
disk image: https://storage.googleapis.com/syzbot-assets/c30be6f36c31/disk-ce7f1a98.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ae9ea347d4d8/vmlinux-ce7f1a98.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d59682a4f33c/bzImage-ce7f1a98.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1e1f9d...@syzkaller.appspotmail.com
comedi comedi1: c6xdigio: I/O port conflict (0x401,3)
==================================================================
BUG: KASAN: slab-use-after-free in sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:510
Read of size 8 at addr ffff88814c9b5030 by task syz.0.18/6068
CPU: 0 UID: 0 PID: 6068 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
print_report+0xca/0x240 mm/kasan/report.c:482
kasan_report+0x118/0x150 mm/kasan/report.c:595
sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:510
comedi_device_detach drivers/comedi/drivers.c:215 [inline]
comedi_device_attach+0x5d4/0x720 drivers/comedi/drivers.c:1011
do_devconfig_ioctl drivers/comedi/comedi_fops.c:872 [inline]
comedi_unlocked_ioctl+0x5ff/0x1020 drivers/comedi/comedi_fops.c:2178
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9aee78eec9
RAX: ffffffffffffffda RBX: 00007f9aee9e5fa0 RCX: 00007f9aee78eec9
RDX: 0000200000000080 RSI: 0000000040946400 RDI: 0000000000000004
RBP: 00007f9aee811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9aee9e5fa0 R14: 00007f9aee9e5fa0 R15: 0000000000000003
</TASK>
Allocated by task 6067:
kasan_save_stack mm/kasan/common.c:56 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:417
kasan_kmalloc include/linux/kasan.h:262 [inline]
__kmalloc_cache_noprof+0x3d5/0x6f0 mm/slub.c:5723
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
do_devconfig_ioctl drivers/comedi/comedi_fops.c:872 [inline]
comedi_unlocked_ioctl+0x5ff/0x1020 drivers/comedi/comedi_fops.c:2178
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 6067:
kasan_save_stack mm/kasan/common.c:56 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
__kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587
kasan_save_free_info mm/kasan/kasan.h:406 [inline]
poison_slab_object mm/kasan/common.c:252 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284
kasan_slab_free include/linux/kasan.h:234 [inline]
slab_free_hook mm/slub.c:2507 [inline]
slab_free mm/slub.c:6557 [inline]
kfree+0x19a/0x6d0 mm/slub.c:6765
comedi_device_detach drivers/comedi/drivers.c:215 [inline]
comedi_device_attach+0x5d4/0x720 drivers/comedi/drivers.c:1011
do_devconfig_ioctl drivers/comedi/comedi_fops.c:872 [inline]
comedi_unlocked_ioctl+0x5ff/0x1020 drivers/comedi/comedi_fops.c:2178
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff88814c9b5000
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x14c9b4
page_type: f5(slab)
raw: 057ff00000000040 ffff88813fe26b40 0000000000000000 0000000000000001
raw: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff88813fe26b40 0000000000000000 0000000000000001
head: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 057ff00000000001 ffffea0005326d01 00000000ffffffff 00000000ffffffff
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1850
prep_new_page mm/page_alloc.c:1858 [inline]
get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3884
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5183
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
alloc_slab_page mm/slub.c:3023 [inline]
allocate_slab+0x96/0x3a0 mm/slub.c:3196
new_slab mm/slub.c:3250 [inline]
___slab_alloc+0xe94/0x1920 mm/slub.c:4626
__slab_alloc+0x65/0x100 mm/slub.c:4745
__slab_alloc_node mm/slub.c:4821 [inline]
slab_alloc_node mm/slub.c:5232 [inline]
__do_kmalloc_node mm/slub.c:5601 [inline]
__kmalloc_node_track_caller_noprof+0x5c7/0x800 mm/slub.c:5711
__do_krealloc mm/slub.c:6907 [inline]
krealloc_node_align_noprof+0x140/0x390 mm/slub.c:6966
add_sysfs_param+0xd4/0xa30 kernel/params.c:655
kernel_add_sysfs_param+0x7f/0xe0 kernel/params.c:812
param_sysfs_builtin+0x18a/0x230 kernel/params.c:851
param_sysfs_builtin_init+0x23/0x30 kernel/params.c:987
do_one_initcall+0x236/0x820 init/main.c:1283
do_initcall_level+0x104/0x190 init/main.c:1345
do_initcalls+0x59/0xa0 init/main.c:1361
ffff88814c9b4f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88814c9b5000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88814c9b5080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88814c9b5100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
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: ce7f1a983b07 Add linux-next specific files for 20250923
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=170b8d34580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1be6fa3d47bce66e
dashboard link: https://syzkaller.appspot.com/bug?extid=1e1f9de12b2231befdaa
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13fe94e2580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11912142580000
CC: [da...@kernel.org gre...@linuxfoundation.org linux-...@vger.kernel.org linux-...@vger.kernel.org raf...@kernel.org]
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c30be6f36c31/disk-ce7f1a98.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ae9ea347d4d8/vmlinux-ce7f1a98.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d59682a4f33c/bzImage-ce7f1a98.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1e1f9d...@syzkaller.appspotmail.com
==================================================================
BUG: KASAN: slab-use-after-free in sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:510
Read of size 8 at addr ffff88814c9b5030 by task syz.0.18/6068
CPU: 0 UID: 0 PID: 6068 Comm: syz.0.18 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_report+0xca/0x240 mm/kasan/report.c:482
kasan_report+0x118/0x150 mm/kasan/report.c:595
sysfs_remove_file_ns+0x3d/0x70 fs/sysfs/file.c:510
remove_bind_files drivers/base/bus.c:605 [inline]
bus_remove_driver+0x198/0x2f0 drivers/base/bus.c:743
comedi_device_detach_locked+0x178/0x750 drivers/comedi/drivers.c:207
bus_remove_driver+0x198/0x2f0 drivers/base/bus.c:743
comedi_device_detach drivers/comedi/drivers.c:215 [inline]
comedi_device_attach+0x5d4/0x720 drivers/comedi/drivers.c:1011
do_devconfig_ioctl drivers/comedi/comedi_fops.c:872 [inline]
comedi_unlocked_ioctl+0x5ff/0x1020 drivers/comedi/comedi_fops.c:2178
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9aee78eec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe7540fbc8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f9aee9e5fa0 RCX: 00007f9aee78eec9
RDX: 0000200000000080 RSI: 0000000040946400 RDI: 0000000000000004
RBP: 00007f9aee811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9aee9e5fa0 R14: 00007f9aee9e5fa0 R15: 0000000000000003
</TASK>
Allocated by task 6067:
kasan_save_stack mm/kasan/common.c:56 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:417
kasan_kmalloc include/linux/kasan.h:262 [inline]
__kmalloc_cache_noprof+0x3d5/0x6f0 mm/slub.c:5723
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
bus_add_driver+0x162/0x640 drivers/base/bus.c:662
driver_register+0x23a/0x320 drivers/base/driver.c:249
c6xdigio_attach+0x94/0x890 drivers/comedi/drivers/c6xdigio.c:253
comedi_device_attach+0x51f/0x720 drivers/comedi/drivers.c:1007
driver_register+0x23a/0x320 drivers/base/driver.c:249
c6xdigio_attach+0x94/0x890 drivers/comedi/drivers/c6xdigio.c:253
do_devconfig_ioctl drivers/comedi/comedi_fops.c:872 [inline]
comedi_unlocked_ioctl+0x5ff/0x1020 drivers/comedi/comedi_fops.c:2178
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 6067:
kasan_save_stack mm/kasan/common.c:56 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
__kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587
kasan_save_free_info mm/kasan/kasan.h:406 [inline]
poison_slab_object mm/kasan/common.c:252 [inline]
__kasan_slab_free+0x5c/0x80 mm/kasan/common.c:284
kasan_slab_free include/linux/kasan.h:234 [inline]
slab_free_hook mm/slub.c:2507 [inline]
slab_free mm/slub.c:6557 [inline]
kfree+0x19a/0x6d0 mm/slub.c:6765
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x22b/0x480 lib/kobject.c:737
bus_remove_driver+0x245/0x2f0 drivers/base/bus.c:749
comedi_device_detach_locked+0x178/0x750 drivers/comedi/drivers.c:207
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x22b/0x480 lib/kobject.c:737
bus_remove_driver+0x245/0x2f0 drivers/base/bus.c:749
comedi_device_detach drivers/comedi/drivers.c:215 [inline]
comedi_device_attach+0x5d4/0x720 drivers/comedi/drivers.c:1011
do_devconfig_ioctl drivers/comedi/comedi_fops.c:872 [inline]
comedi_unlocked_ioctl+0x5ff/0x1020 drivers/comedi/comedi_fops.c:2178
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff88814c9b5000
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 48 bytes inside of
freed 256-byte region [ffff88814c9b5000, ffff88814c9b5100)
The buggy address is located 48 bytes inside of
The buggy address belongs to the physical page:
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
anon flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88813fe26b40 0000000000000000 0000000000000001
raw: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff88813fe26b40 0000000000000000 0000000000000001
head: 0000000000000000 0000000080100010 00000000f5000000 0000000000000000
head: 057ff00000000001 ffffea0005326d01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 27843801833, free_ts 0
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1850
prep_new_page mm/page_alloc.c:1858 [inline]
get_page_from_freelist+0x2365/0x2440 mm/page_alloc.c:3884
__alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5183
alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
alloc_slab_page mm/slub.c:3023 [inline]
allocate_slab+0x96/0x3a0 mm/slub.c:3196
new_slab mm/slub.c:3250 [inline]
___slab_alloc+0xe94/0x1920 mm/slub.c:4626
__slab_alloc+0x65/0x100 mm/slub.c:4745
__slab_alloc_node mm/slub.c:4821 [inline]
slab_alloc_node mm/slub.c:5232 [inline]
__do_kmalloc_node mm/slub.c:5601 [inline]
__kmalloc_node_track_caller_noprof+0x5c7/0x800 mm/slub.c:5711
__do_krealloc mm/slub.c:6907 [inline]
krealloc_node_align_noprof+0x140/0x390 mm/slub.c:6966
add_sysfs_param+0xd4/0xa30 kernel/params.c:655
kernel_add_sysfs_param+0x7f/0xe0 kernel/params.c:812
param_sysfs_builtin+0x18a/0x230 kernel/params.c:851
param_sysfs_builtin_init+0x23/0x30 kernel/params.c:987
do_one_initcall+0x236/0x820 init/main.c:1283
do_initcall_level+0x104/0x190 init/main.c:1345
do_initcalls+0x59/0xa0 init/main.c:1361
page_owner free stack trace missing
Memory state around the buggy address:
ffff88814c9b4f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
Memory state around the buggy address:
ffff88814c9b4f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88814c9b5000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88814c9b5080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88814c9b5100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
---
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.
syzbot
Sep 24, 2025, 2:31:18 AM (2 days ago) Sep 24
to syzkaller-upst...@googlegroups.com
Sending this report to the next reporting stage.
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