From: syzbot <syzbot+9cb1ac7fce4944ba9165@syzkaller.appspotmail.com>
To: dakr@kernel.org, driver-core@lists.linux.dev,
gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
rafael@kernel.org, syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [kernel?] KASAN: slab-use-after-free Write in bus_for_each_drv
Date: Mon, 10 Aug 2026 15:39:30 -0700 [thread overview]
Message-ID: <6a7a5322.01d0871a.3a0d52.00ae.GAE@google.com> (raw)
In-Reply-To: <6a7919c6.9c11d2ce.289b96.00de.GAE@google.com>
syzbot has found a reproducer for the following issue on:
HEAD commit: d58772d8520c Merge tag 'regmap-fix-v7.2-rc7' of git://git...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16e012c6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6ddb3079499f48cb
dashboard link: https://syzkaller.appspot.com/bug?extid=9cb1ac7fce4944ba9165
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=1719d132580000
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9cb1ac7fce4944ba9165@syzkaller.appspotmail.com
Need at least one configuration in g3.
udc dummy_udc.0: failed to start g3: -22
configfs-gadget.g3 gadget.0: probe with driver configfs-gadget.g3 failed with error -22
==================================================================
BUG: KASAN: slab-use-after-free in knode_set_klist lib/klist.c:60 [inline]
BUG: KASAN: slab-use-after-free in klist_release lib/klist.c:201 [inline]
BUG: KASAN: slab-use-after-free in kref_put include/linux/kref.h:65 [inline]
BUG: KASAN: slab-use-after-free in klist_dec_and_del+0x386/0x3d0 lib/klist.c:206
Write of size 8 at addr ffff88803fe920e0 by task syz-executor321/5936
CPU: 1 UID: 0 PID: 5936 Comm: syz-executor321 Not tainted syzkaller #0 PREEMPT_{RT,(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
knode_set_klist lib/klist.c:60 [inline]
klist_release lib/klist.c:201 [inline]
kref_put include/linux/kref.h:65 [inline]
klist_dec_and_del+0x386/0x3d0 lib/klist.c:206
klist_next+0xc3/0x2f0 lib/klist.c:386
next_driver drivers/base/bus.c:457 [inline]
bus_for_each_drv+0x268/0x2f0 drivers/base/bus.c:499
__device_attach+0x2c7/0x450 drivers/base/dd.c:1098
device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1153
bus_probe_device+0x12d/0x220 drivers/base/bus.c:620
device_add+0x7d7/0xb80 drivers/base/core.c:3772
usb_add_gadget+0x47d/0x700 drivers/usb/gadget/udc/core.c:1461
usb_add_gadget_udc_release+0x1a4/0x1f0 drivers/usb/gadget/udc/core.c:1517
dummy_udc_probe+0x6e1/0x7e0 drivers/usb/gadget/udc/dummy_hcd.c:1121
platform_probe+0xf9/0x190 drivers/base/platform.c:1439
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
device_driver_attach+0xe0/0x1d0 drivers/base/dd.c:1203
bind_store+0x1d3/0x220 drivers/base/bus.c:267
kernfs_fop_write_iter+0x3a5/0x540 fs/kernfs/file.c:345
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x61e/0xbb0 fs/read_write.c:687
ksys_write+0x156/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f453d1641de
Code: 08 0f 85 f5 e2 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 90 41 57 41 56 4d 89 c6 41 55 4d 89 cd 41 54 55 53 48 83 ec 08
RSP: 002b:00007f453d106f98 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f453d1076c0 RCX: 00007f453d1641de
RDX: 000000000000000b RSI: 00007f453d1ad1b9 RDI: 0000000000000003
RBP: 0000000000000005 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000003
R13: 0000000000000010 R14: 00007ffca4345660 R15: 00007ffca4345748
</TASK>
Allocated by task 5940:
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+0x3d2/0x6b0 mm/slub.c:5489
_kmalloc_noprof include/linux/slab.h:988 [inline]
_kzalloc_noprof include/linux/slab.h:1309 [inline]
bus_add_driver+0x165/0x670 drivers/base/bus.c:747
driver_register+0x23a/0x320 drivers/base/driver.c:174
usb_gadget_register_driver_owner+0xf9/0x270 drivers/usb/gadget/udc/core.c:1752
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+0x33a/0x430 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x61e/0xbb0 fs/read_write.c:687
ksys_write+0x156/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 5940:
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: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:2677 [inline]
slab_free mm/slub.c:6377 [inline]
kfree+0x1c5/0x6c0 mm/slub.c:6692
kobject_cleanup lib/kobject.c:689 [inline]
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0x222/0x550 lib/kobject.c:737
bus_remove_driver+0x248/0x320 drivers/base/bus.c:834
usb_gadget_register_driver_owner+0x223/0x270 drivers/usb/gadget/udc/core.c:1774
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+0x33a/0x430 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x61e/0xbb0 fs/read_write.c:687
ksys_write+0x156/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
The buggy address belongs to the object at ffff88803fe92000
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 224 bytes inside of
freed 512-byte region [ffff88803fe92000, ffff88803fe92200)
The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3fe90
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff88813ffb3c80 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 0080000000000040 ffff88813ffb3c80 dead000000000100 dead000000000122
head: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000
head: 0080000000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5633, tgid 5633 (syz-executor), ts 102640041714, free_ts 80262861649
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1859
prep_new_page mm/page_alloc.c:1867 [inline]
get_page_from_freelist+0x262a/0x26a0 mm/page_alloc.c:3946
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5304
alloc_slab_page mm/slub.c:3266 [inline]
allocate_slab+0x79/0x5e0 mm/slub.c:3380
new_slab mm/slub.c:3426 [inline]
refill_objects+0x2d8/0x350 mm/slub.c:7310
refill_sheaf mm/slub.c:2804 [inline]
__pcs_replace_empty_main+0x330/0x690 mm/slub.c:4675
alloc_from_pcs mm/slub.c:4773 [inline]
slab_alloc_node mm/slub.c:4905 [inline]
__kmalloc_cache_noprof+0x468/0x6b0 mm/slub.c:5485
_kmalloc_noprof include/linux/slab.h:988 [inline]
_kzalloc_noprof include/linux/slab.h:1309 [inline]
mca_alloc net/ipv6/mcast.c:871 [inline]
__ipv6_dev_mc_inc+0x447/0xa40 net/ipv6/mcast.c:961
ipv6_add_dev+0xe83/0x1400 net/ipv6/addrconf.c:475
addrconf_notify+0x771/0x1050 net/ipv6/addrconf.c:3685
notifier_call_chain+0x1a5/0x3d0 kernel/notifier.c:85
call_netdevice_notifiers_extack net/core/dev.c:2288 [inline]
call_netdevice_notifiers net/core/dev.c:2302 [inline]
register_netdevice+0x18c0/0x1ed0 net/core/dev.c:11484
__ip_tunnel_create+0x3e8/0x550 net/ipv4/ip_tunnel.c:268
ip_tunnel_init_net+0x2e5/0x820 net/ipv4/ip_tunnel.c:1150
ops_init+0x35d/0x5d0 net/core/net_namespace.c:137
setup_net+0x118/0x350 net/core/net_namespace.c:446
page last free pid 5564 tgid 5564 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
__free_pages_prepare mm/page_alloc.c:1406 [inline]
__free_frozen_pages+0x10e7/0x11c0 mm/page_alloc.c:2950
__slab_free+0x252/0x2a0 mm/slub.c:5741
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x99/0x100 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:4584 [inline]
slab_alloc_node mm/slub.c:4917 [inline]
__kmalloc_cache_noprof+0x351/0x6b0 mm/slub.c:5485
_kmalloc_noprof include/linux/slab.h:988 [inline]
single_open+0x5a/0x240 fs/seq_file.c:576
do_dentry_open+0x849/0x1420 fs/open.c:947
vfs_open+0x3b/0x350 fs/open.c:1052
do_open fs/namei.c:4700 [inline]
path_openat+0x2e60/0x3850 fs/namei.c:4863
do_file_open+0x23e/0x4a0 fs/namei.c:4892
do_sys_openat2+0x115/0x200 fs/open.c:1368
do_sys_open fs/open.c:1374 [inline]
__do_sys_openat fs/open.c:1390 [inline]
__se_sys_openat fs/open.c:1385 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1385
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Memory state around the buggy address:
ffff88803fe91f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88803fe92000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88803fe92080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88803fe92100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88803fe92180: 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.
prev parent reply other threads:[~2026-08-10 22:39 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-10 0:22 [syzbot] [kernel?] KASAN: slab-use-after-free Write in bus_for_each_drv syzbot
2026-08-10 22:39 ` syzbot [this message]
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