Message-ID: <000000000000443bc506117d05c1@google.com>
Date: Fri, 16 Feb 2024 02:15:17 -0800
From: syzbot <syzbot+615e0ade319f27aeab87@...kaller.appspotmail.com>
To: gregkh@...uxfoundation.org, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com, tj@...nel.org
Subject: [syzbot] [kernfs?] KASAN: slab-use-after-free Read in kernfs_get

Hello,

syzbot found the following issue on:

HEAD commit:    4f5e5092fdbf Merge tag 'net-6.8-rc5' of git://git.kernel.o..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14c58494180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=1d7c92dd8d5c7a1e
dashboard link: https://syzkaller.appspot.com/bug?extid=615e0ade319f27aeab87
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d430539932db/disk-4f5e5092.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/6369586e33b7/vmlinux-4f5e5092.xz
kernel image: https://storage.googleapis.com/syzbot-assets/9c1e38f80254/bzImage-4f5e5092.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+615e0ade319f27aeab87@...kaller.appspotmail.com

usb 4-1: Direct firmware load for ueagle-atm/adi930.fw failed with error -2
usb 4-1: Falling back to sysfs fallback for: ueagle-atm/adi930.fw
==================================================================
BUG: KASAN: slab-use-after-free in instrument_atomic_read include/linux/instrumented.h:68 [inline]
BUG: KASAN: slab-use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
BUG: KASAN: slab-use-after-free in kernfs_get+0x20/0x90 fs/kernfs/dir.c:526
Read of size 4 at addr ffff888029e1f3e0 by task kworker/0:0/8

CPU: 0 PID: 8 Comm: kworker/0:0 Not tainted 6.8.0-rc4-syzkaller-00180-g4f5e5092fdbf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
Workqueue: events request_firmware_work_func
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x167/0x540 mm/kasan/report.c:488
 kasan_report+0x142/0x180 mm/kasan/report.c:601
 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
 instrument_atomic_read include/linux/instrumented.h:68 [inline]
 atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
 kernfs_get+0x20/0x90 fs/kernfs/dir.c:526
 sysfs_get include/linux/sysfs.h:653 [inline]
 create_dir lib/kobject.c:87 [inline]
 kobject_add_internal+0x483/0x8a0 lib/kobject.c:238
 kobject_add_varg lib/kobject.c:372 [inline]
 kobject_add+0x152/0x220 lib/kobject.c:424
 device_add+0x4b5/0xca0 drivers/base/core.c:3563
 fw_load_sysfs_fallback drivers/base/firmware_loader/fallback.c:86 [inline]
 fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:162 [inline]
 firmware_fallback_sysfs+0x307/0x9e0 drivers/base/firmware_loader/fallback.c:238
 _request_firmware+0xc97/0x1250 drivers/base/firmware_loader/main.c:910
 request_firmware_work_func+0x12a/0x280 drivers/base/firmware_loader/main.c:1161
 process_one_work kernel/workqueue.c:2633 [inline]
 process_scheduled_works+0x913/0x1420 kernel/workqueue.c:2706
 worker_thread+0xa5f/0x1000 kernel/workqueue.c:2787
 kthread+0x2ef/0x390 kernel/kthread.c:388
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242
 </TASK>

Allocated by task 8:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 unpoison_slab_object mm/kasan/common.c:314 [inline]
 __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:340
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slub.c:3813 [inline]
 slab_alloc_node mm/slub.c:3860 [inline]
 kmem_cache_alloc+0x16f/0x340 mm/slub.c:3867
 kmem_cache_zalloc include/linux/slab.h:701 [inline]
 __kernfs_new_node+0xd8/0x880 fs/kernfs/dir.c:615
 kernfs_new_node+0x13a/0x240 fs/kernfs/dir.c:691
 kernfs_create_dir_ns+0x43/0x120 fs/kernfs/dir.c:1052
 sysfs_create_dir_ns+0x189/0x3a0 fs/sysfs/dir.c:59
 create_dir lib/kobject.c:73 [inline]
 kobject_add_internal+0x40d/0x8a0 lib/kobject.c:238
 kobject_add_varg lib/kobject.c:372 [inline]
 kobject_add+0x152/0x220 lib/kobject.c:424
 device_add+0x4b5/0xca0 drivers/base/core.c:3563
 fw_load_sysfs_fallback drivers/base/firmware_loader/fallback.c:86 [inline]
 fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:162 [inline]
 firmware_fallback_sysfs+0x307/0x9e0 drivers/base/firmware_loader/fallback.c:238
 _request_firmware+0xc97/0x1250 drivers/base/firmware_loader/main.c:910
 request_firmware_work_func+0x12a/0x280 drivers/base/firmware_loader/main.c:1161
 process_one_work kernel/workqueue.c:2633 [inline]
 process_scheduled_works+0x913/0x1420 kernel/workqueue.c:2706
 worker_thread+0xa5f/0x1000 kernel/workqueue.c:2787
 kthread+0x2ef/0x390 kernel/kthread.c:388
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242

Freed by task 9:
 kasan_save_stack mm/kasan/common.c:47 [inline]
 kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
 kasan_save_free_info+0x4e/0x60 mm/kasan/generic.c:640
 poison_slab_object+0xa6/0xe0 mm/kasan/common.c:241
 __kasan_slab_free+0x34/0x70 mm/kasan/common.c:257
 kasan_slab_free include/linux/kasan.h:184 [inline]
 slab_free_hook mm/slub.c:2121 [inline]
 slab_free mm/slub.c:4299 [inline]
 kmem_cache_free+0x102/0x2a0 mm/slub.c:4363
 kernfs_put+0x2a4/0x420 fs/kernfs/dir.c:569
 __kernfs_remove+0x76e/0x880 fs/kernfs/dir.c:1499
 kernfs_remove+0x7a/0xa0 fs/kernfs/dir.c:1519
 __kobject_del+0xd1/0x300 lib/kobject.c:601
 kobject_del+0x45/0x60 lib/kobject.c:624
 device_del+0x83d/0xa30 drivers/base/core.c:3834
 usb_disconnect+0x60b/0x950 drivers/usb/core/hub.c:2295
 hub_port_connect drivers/usb/core/hub.c:5323 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5623 [inline]
 port_event drivers/usb/core/hub.c:5783 [inline]
 hub_event+0x1e62/0x50f0 drivers/usb/core/hub.c:5865
 process_one_work kernel/workqueue.c:2633 [inline]
 process_scheduled_works+0x913/0x1420 kernel/workqueue.c:2706
 worker_thread+0xa5f/0x1000 kernel/workqueue.c:2787
 kthread+0x2ef/0x390 kernel/kthread.c:388
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242

The buggy address belongs to the object at ffff888029e1f3e0
 which belongs to the cache kernfs_node_cache of size 168
The buggy address is located 0 bytes inside of
 freed 168-byte region [ffff888029e1f3e0, ffff888029e1f488)

The buggy address belongs to the physical page:
page:ffffea0000a787c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29e1f
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff8880162b4dc0 ffffea0001d9c7c0 0000000000000004
raw: 0000000000000000 0000000080100010 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 20250, tgid 20246 (syz-executor.1), ts 407489926347, free_ts 399703976306
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1533
 prep_new_page mm/page_alloc.c:1540 [inline]
 get_page_from_freelist+0x33ea/0x3580 mm/page_alloc.c:3311
 __alloc_pages+0x255/0x680 mm/page_alloc.c:4567
 __alloc_pages_node include/linux/gfp.h:238 [inline]
 alloc_pages_node include/linux/gfp.h:261 [inline]
 alloc_slab_page+0x5f/0x160 mm/slub.c:2190
 allocate_slab mm/slub.c:2354 [inline]
 new_slab+0x84/0x2f0 mm/slub.c:2407
 ___slab_alloc+0xd17/0x13e0 mm/slub.c:3540
 __slab_alloc mm/slub.c:3625 [inline]
 __slab_alloc_node mm/slub.c:3678 [inline]
 slab_alloc_node mm/slub.c:3850 [inline]
 kmem_cache_alloc+0x24d/0x340 mm/slub.c:3867
 kmem_cache_zalloc include/linux/slab.h:701 [inline]
 __kernfs_new_node+0xd8/0x880 fs/kernfs/dir.c:615
 kernfs_new_node+0x13a/0x240 fs/kernfs/dir.c:691
 __kernfs_create_file+0x49/0x2f0 fs/kernfs/file.c:1025
 sysfs_add_file_mode_ns+0x24a/0x310 fs/sysfs/file.c:307
 create_files fs/sysfs/group.c:64 [inline]
 internal_create_group+0x4f4/0xf20 fs/sysfs/group.c:152
 internal_create_groups fs/sysfs/group.c:192 [inline]
 sysfs_create_groups+0x56/0x120 fs/sysfs/group.c:218
 device_add_groups drivers/base/core.c:2727 [inline]
 device_add_attrs+0x199/0x600 drivers/base/core.c:2847
 device_add+0x57d/0xca0 drivers/base/core.c:3579
 netdev_register_kobject+0x17e/0x310 net/core/net-sysfs.c:2055
page last free pid 55 tgid 55 stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1140 [inline]
 free_unref_page_prepare+0x968/0xa90 mm/page_alloc.c:2346
 free_unref_page+0x37/0x3f0 mm/page_alloc.c:2486
 kasan_depopulate_vmalloc_pte+0x74/0x90 mm/kasan/shadow.c:415
 apply_to_pte_range mm/memory.c:2619 [inline]
 apply_to_pmd_range mm/memory.c:2663 [inline]
 apply_to_pud_range mm/memory.c:2699 [inline]
 apply_to_p4d_range mm/memory.c:2735 [inline]
 __apply_to_page_range+0x8ec/0xe40 mm/memory.c:2769
 kasan_release_vmalloc+0x9a/0xb0 mm/kasan/shadow.c:532
 __purge_vmap_area_lazy+0x163f/0x1a10 mm/vmalloc.c:1770
 drain_vmap_area_work+0x40/0xd0 mm/vmalloc.c:1804
 process_one_work kernel/workqueue.c:2633 [inline]
 process_scheduled_works+0x913/0x1420 kernel/workqueue.c:2706
 worker_thread+0xa5f/0x1000 kernel/workqueue.c:2787
 kthread+0x2ef/0x390 kernel/kthread.c:388
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:242

Memory state around the buggy address:
 ffff888029e1f280: fb fb fb fc fc fc fc fc fc fc fc fc fc fb fb fb
 ffff888029e1f300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888029e1f380: fb fb fc fc fc fc fc fc fc fc fc fc fa fb fb fb
                                                       ^
 ffff888029e1f400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888029e1f480: fb fc fc fc fc fc fc fc fc fc fc 00 00 00 00 00
==================================================================


---
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