KASAN: use-after-free Write in gadgetfs_kill_sb

Status: fixed on 2023/06/08 14:41
Subsystems: usb
[Documentation on labels]
Reported-by: syzbot+33d7ad66d65044b93f16@syzkaller.appspotmail.com
Fix commit: d18dcfe9860e USB: gadgetfs: Fix race between mounting and unmounting
First crash: 1346d, last: 1311d
Cause bisection: failed (error log, bisect log)
  
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[PATCH] USB: gadgetfs: Fix race between mounting and unmounting 1 (1) 2022/12/23 14:59
[syzbot] KASAN: use-after-free Write in gadgetfs_kill_sb 3 (6) 2022/12/14 15:19
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Write in gadgetfs_kill_sb prio:normal actionable usb 22 C 3 7d09h 16d 0/29 upstream: reported C repro on 2026/08/04 02:08
▶ ▼ Last patch testing requests (2)
Created Duration User Patch Repo Result
2022/12/14 01:00 28m stern@rowland.harvard.edu patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ 830b3c68c1fb OK log
2022/12/13 16:05 27m stern@rowland.harvard.edu patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ 830b3c68c1fb report log

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
BUG: KASAN: use-after-free in atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:176 [inline]
BUG: KASAN: use-after-free in __refcount_sub_and_test include/linux/refcount.h:272 [inline]
BUG: KASAN: use-after-free in __refcount_dec_and_test include/linux/refcount.h:315 [inline]
BUG: KASAN: use-after-free in refcount_dec_and_test include/linux/refcount.h:333 [inline]
BUG: KASAN: use-after-free in put_dev drivers/usb/gadget/legacy/inode.c:159 [inline]
BUG: KASAN: use-after-free in gadgetfs_kill_sb+0x33/0x100 drivers/usb/gadget/legacy/inode.c:2086
Write of size 4 at addr ffff88802a065040 by task syz-executor154/5154

CPU: 1 PID: 5154 Comm: syz-executor154 Not tainted 6.1.0-syzkaller-13139-gf9ff5644bcc0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1b1/0x290 lib/dump_stack.c:106
 print_address_description+0x74/0x340 mm/kasan/report.c:306
 print_report+0x107/0x1f0 mm/kasan/report.c:417
 kasan_report+0xcd/0x100 mm/kasan/report.c:517
 kasan_check_range+0x2a7/0x2e0 mm/kasan/generic.c:189
 instrument_atomic_read_write include/linux/instrumented.h:102 [inline]
 atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:176 [inline]
 __refcount_sub_and_test include/linux/refcount.h:272 [inline]
 __refcount_dec_and_test include/linux/refcount.h:315 [inline]
 refcount_dec_and_test include/linux/refcount.h:333 [inline]
 put_dev drivers/usb/gadget/legacy/inode.c:159 [inline]
 gadgetfs_kill_sb+0x33/0x100 drivers/usb/gadget/legacy/inode.c:2086
 deactivate_locked_super+0xa7/0xf0 fs/super.c:332
 vfs_get_super fs/super.c:1149 [inline]
 get_tree_single+0xd0/0x160 fs/super.c:1165
 vfs_get_tree+0x88/0x270 fs/super.c:1489
 vfs_fsconfig_locked fs/fsopen.c:232 [inline]
 __do_sys_fsconfig fs/fsopen.c:439 [inline]
 __se_sys_fsconfig+0xbc0/0x1060 fs/fsopen.c:314
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f30d255fe09
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 90 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffe3583a38 EFLAGS: 00000246 ORIG_RAX: 00000000000001af
RAX: ffffffffffffffda RBX: 00000000000f4240 RCX: 00007f30d255fe09
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000c9da
R13: 00007fffe3583a4c R14: 00007fffe3583a60 R15: 00007fffe3583a50
 </TASK>

Allocated by task 5151:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x3d/0x60 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:371 [inline]
 __kasan_kmalloc+0x97/0xb0 mm/kasan/common.c:380
 kmalloc include/linux/slab.h:580 [inline]
 kzalloc include/linux/slab.h:720 [inline]
 dev_new drivers/usb/gadget/legacy/inode.c:170 [inline]
 gadgetfs_fill_super+0x2f9/0x8a0 drivers/usb/gadget/legacy/inode.c:2041
 vfs_get_super fs/super.c:1128 [inline]
 get_tree_single+0xb4/0x160 fs/super.c:1165
 vfs_get_tree+0x88/0x270 fs/super.c:1489
 vfs_fsconfig_locked fs/fsopen.c:232 [inline]
 __do_sys_fsconfig fs/fsopen.c:439 [inline]
 __se_sys_fsconfig+0xbc0/0x1060 fs/fsopen.c:314
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 5151:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x3d/0x60 mm/kasan/common.c:52
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:518
 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1781 [inline]
 slab_free_freelist_hook+0x12e/0x1a0 mm/slub.c:1807
 slab_free mm/slub.c:3787 [inline]
 __kmem_cache_free+0x71/0x110 mm/slub.c:3800
 put_dev drivers/usb/gadget/legacy/inode.c:163 [inline]
 gadgetfs_kill_sb+0x8a/0x100 drivers/usb/gadget/legacy/inode.c:2086
 deactivate_locked_super+0xa7/0xf0 fs/super.c:332
 put_fs_context+0x90/0x7a0 fs/fs_context.c:465
 fscontext_release+0x61/0x80 fs/fsopen.c:73
 __fput+0x3ba/0x880 fs/file_table.c:320
 task_work_run+0x243/0x300 kernel/task_work.c:179
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0x644/0x2150 kernel/exit.c:867
 do_group_exit+0x1fd/0x2b0 kernel/exit.c:1010
 __do_sys_exit_group kernel/exit.c:1021 [inline]
 __se_sys_exit_group kernel/exit.c:1019 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1019
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88802a065000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 64 bytes inside of
 1024-byte region [ffff88802a065000, ffff88802a065400)

The buggy address belongs to the physical page:
page:ffffea0000a81800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2a060
head:ffffea0000a81800 order:3 compound_mapcount:0 subpages_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffff888012841dc0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5059, tgid 5059 (sshd), ts 51612855816, free_ts 46187228809
 prep_new_page mm/page_alloc.c:2531 [inline]
 get_page_from_freelist+0x742/0x7c0 mm/page_alloc.c:4283
 __alloc_pages+0x259/0x560 mm/page_alloc.c:5549
 alloc_slab_page+0xbd/0x190 mm/slub.c:1851
 allocate_slab+0x5e/0x3c0 mm/slub.c:1998
 new_slab mm/slub.c:2051 [inline]
 ___slab_alloc+0x782/0xe20 mm/slub.c:3193
 __slab_alloc mm/slub.c:3292 [inline]
 __slab_alloc_node mm/slub.c:3345 [inline]
 slab_alloc_node mm/slub.c:3442 [inline]
 __kmem_cache_alloc_node+0x25b/0x340 mm/slub.c:3491
 __do_kmalloc_node mm/slab_common.c:967 [inline]
 __kmalloc_node_track_caller+0x9c/0x190 mm/slab_common.c:988
 kmalloc_reserve net/core/skbuff.c:492 [inline]
 __alloc_skb+0x12c/0x2c0 net/core/skbuff.c:565
 alloc_skb_fclone include/linux/skbuff.h:1320 [inline]
 tcp_stream_alloc_skb+0x3c/0x300 net/ipv4/tcp.c:862
 tcp_sendmsg_locked+0xd80/0x40f0 net/ipv4/tcp.c:1325
 tcp_sendmsg+0x2c/0x40 net/ipv4/tcp.c:1483
 sock_sendmsg_nosec net/socket.c:714 [inline]
 sock_sendmsg net/socket.c:734 [inline]
 sock_write_iter+0x3d4/0x540 net/socket.c:1108
 call_write_iter include/linux/fs.h:2186 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x7dc/0xc50 fs/read_write.c:584
 ksys_write+0x177/0x2a0 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1446 [inline]
 free_pcp_prepare+0x751/0x780 mm/page_alloc.c:1496
 free_unref_page_prepare mm/page_alloc.c:3369 [inline]
 free_unref_page+0x19/0x4c0 mm/page_alloc.c:3464
 discard_slab mm/slub.c:2098 [inline]
 __unfreeze_partials+0x1a5/0x1e0 mm/slub.c:2637
 put_cpu_partial+0x106/0x170 mm/slub.c:2713
 qlist_free_all+0x2b/0x70 mm/kasan/quarantine.c:187
 kasan_quarantine_reduce+0x156/0x170 mm/kasan/quarantine.c:294
 __kasan_slab_alloc+0x1f/0x70 mm/kasan/common.c:302
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook mm/slab.h:761 [inline]
 slab_alloc_node mm/slub.c:3452 [inline]
 slab_alloc mm/slub.c:3460 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3467 [inline]
 kmem_cache_alloc+0x1b3/0x350 mm/slub.c:3476
 getname_flags+0xb8/0x4e0 fs/namei.c:139
 vfs_fstatat fs/stat.c:269 [inline]
 __do_sys_newfstatat fs/stat.c:440 [inline]
 __se_sys_newfstatat+0xcb/0x7d0 fs/stat.c:434
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff88802a064f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802a064f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802a065000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff88802a065080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802a065100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2022/12/18 18:05 upstream f9ff5644bcc0 05494336 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: use-after-free Write in gadgetfs_kill_sb
2022/12/12 21:20 upstream 830b3c68c1fb 67be1ae7 .config strace log report syz C ci2-upstream-fs KASAN: use-after-free Write in gadgetfs_kill_sb
2023/01/16 11:54 upstream 5dc4c995db9e a63719e7 .config console log report info ci2-upstream-fs KASAN: use-after-free Write in gadgetfs_kill_sb
2022/12/29 02:29 upstream 1b929c02afd3 44712fbc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs KASAN: use-after-free Write in gadgetfs_kill_sb
2022/12/12 20:23 upstream 830b3c68c1fb 67be1ae7 .config console log report info ci2-upstream-fs KASAN: use-after-free Write in gadgetfs_kill_sb
* Struck through repros no longer work on HEAD.