syzbot


KASAN: use-after-free Read in kernfs_get

Status: premoderation: reported on 2022/10/18 19:44
Reported-by: syzbot+2165a0748e72cbc7f2df@syzkaller.appspotmail.com
First crash: 107d, last: 35d
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: use-after-free Read in kernfs_get 8 204d 326d 0/24 auto-obsoleted due to no activity on 2022/11/11 09:18
upstream KASAN: use-after-free Read in kernfs_get (2) 1 77d 73d 0/24 upstream: reported on 2022/11/22 13:33

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:71 [inline]
BUG: KASAN: use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
BUG: KASAN: use-after-free in kernfs_get+0x21/0x90 fs/kernfs/dir.c:504
Read of size 4 at addr ffff88811677f3e8 by task kworker/1:31/2538

CPU: 1 PID: 2538 Comm: kworker/1:31 Not tainted 5.15.78-syzkaller-00911-gc73b4619ad86 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: events flush_stashed_error_work
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106
 print_address_description+0x87/0x3d0 mm/kasan/report.c:256
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x1a6/0x1f0 mm/kasan/report.c:452
 kasan_check_range+0x2aa/0x2e0 mm/kasan/generic.c:189
 __kasan_check_read+0x11/0x20 mm/kasan/shadow.c:31
 instrument_atomic_read include/linux/instrumented.h:71 [inline]
 atomic_read include/linux/atomic/atomic-instrumented.h:27 [inline]
 kernfs_get+0x21/0x90 fs/kernfs/dir.c:504
 sysfs_notify+0x9a/0xd0 fs/sysfs/file.c:190
 ext4_notify_error_sysfs+0x25/0x30 fs/ext4/sysfs.c:511
 flush_stashed_error_work+0x305/0x320
 process_one_work+0x6db/0xc00 kernel/workqueue.c:2313
 worker_thread+0xb3e/0x1340 kernel/workqueue.c:2460
 kthread+0x41c/0x500 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>

Allocated by task 3508:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:433 [inline]
 __kasan_slab_alloc+0xb2/0xe0 mm/kasan/common.c:466
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook mm/slab.h:550 [inline]
 slab_alloc_node mm/slub.c:3236 [inline]
 slab_alloc mm/slub.c:3244 [inline]
 kmem_cache_alloc+0x189/0x2f0 mm/slub.c:3249
 kmem_cache_zalloc include/linux/slab.h:711 [inline]
 __kernfs_new_node+0xdb/0x6e0 fs/kernfs/dir.c:593
 kernfs_new_node fs/kernfs/dir.c:655 [inline]
 kernfs_create_dir_ns+0x9b/0x230 fs/kernfs/dir.c:991
 sysfs_create_dir_ns+0x181/0x390 fs/sysfs/dir.c:59
 create_dir lib/kobject.c:89 [inline]
 kobject_add_internal+0x766/0xda0 lib/kobject.c:255
 kobject_add_varg lib/kobject.c:390 [inline]
 kobject_init_and_add+0x123/0x190 lib/kobject.c:473
 ext4_register_sysfs+0xc0/0x2c0 fs/ext4/sysfs.c:524
 ext4_fill_super+0x8983/0x9650 fs/ext4/super.c:4936
 mount_bdev+0x280/0x3b0 fs/super.c:1369
 ext4_mount+0x34/0x40 fs/ext4/super.c:6540
 legacy_get_tree+0xf0/0x190 fs/fs_context.c:610
 vfs_get_tree+0x88/0x290 fs/super.c:1499
 do_new_mount+0x289/0xad0 fs/namespace.c:2994
 path_mount+0x60b/0x1050 fs/namespace.c:3324
 do_mount fs/namespace.c:3337 [inline]
 __do_sys_mount fs/namespace.c:3545 [inline]
 __se_sys_mount+0x2d2/0x3c0 fs/namespace.c:3522
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3522
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 657:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4c/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x126/0x160 mm/kasan/common.c:365
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:373
 kasan_slab_free include/linux/kasan.h:220 [inline]
 slab_free_hook mm/slub.c:1721 [inline]
 slab_free_freelist_hook+0xc9/0x1a0 mm/slub.c:1747
 slab_free mm/slub.c:3515 [inline]
 kmem_cache_free+0x11a/0x2e0 mm/slub.c:3531
 kernfs_put+0x3d9/0x540 fs/kernfs/dir.c:547
 sysfs_put include/linux/sysfs.h:641 [inline]
 __kobject_del+0x10e/0x300 lib/kobject.c:621
 kobject_del+0x45/0x60 lib/kobject.c:643
 ext4_unregister_sysfs+0x91/0xa0 fs/ext4/sysfs.c:558
 ext4_put_super+0x80/0xd70 fs/ext4/super.c:1174
 generic_shutdown_super+0x157/0x2e0 fs/super.c:466
 kill_block_super+0x80/0xe0 fs/super.c:1396
 deactivate_locked_super+0xb0/0x100 fs/super.c:335
 deactivate_super+0xa5/0xd0 fs/super.c:366
 cleanup_mnt+0x45f/0x510 fs/namespace.c:1143
 __cleanup_mnt+0x19/0x20 fs/namespace.c:1150
 task_work_run+0x147/0x1b0 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0xfd/0x110 kernel/entry/common.c:175
 exit_to_user_mode_prepare kernel/entry/common.c:207 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
 syscall_exit_to_user_mode+0x79/0xc0 kernel/entry/common.c:300
 do_syscall_64+0x50/0xd0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff88811677f3e8
 which belongs to the cache kernfs_node_cache of size 136
The buggy address is located 0 bytes inside of
 136-byte region [ffff88811677f3e8, ffff88811677f470)
The buggy address belongs to the page:
page:ffffea000459dfc0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11677f
flags: 0x4000000000000200(slab|zone=1)
raw: 4000000000000200 0000000000000000 dead000000000122 ffff888100276a80
raw: 0000000000000000 0000000000140014 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 3515, ts 2631066974499, free_ts 2618548752105
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1ab/0x1b0 mm/page_alloc.c:2495
 prep_new_page mm/page_alloc.c:2501 [inline]
 get_page_from_freelist+0x38b/0x400 mm/page_alloc.c:4281
 __alloc_pages+0x3a8/0x7c0 mm/page_alloc.c:5548
 allocate_slab+0x62/0x580 mm/slub.c:1928
 new_slab mm/slub.c:1991 [inline]
 ___slab_alloc+0x2e2/0x6f0 mm/slub.c:3024
 __slab_alloc+0x4a/0x90 mm/slub.c:3111
 slab_alloc_node mm/slub.c:3202 [inline]
 slab_alloc mm/slub.c:3244 [inline]
 kmem_cache_alloc+0x205/0x2f0 mm/slub.c:3249
 kmem_cache_zalloc include/linux/slab.h:711 [inline]
 __kernfs_new_node+0xdb/0x6e0 fs/kernfs/dir.c:593
 kernfs_new_node fs/kernfs/dir.c:655 [inline]
 kernfs_create_dir_ns+0x9b/0x230 fs/kernfs/dir.c:991
 internal_create_group+0x29d/0xf60 fs/sysfs/group.c:137
 sysfs_create_group+0x1f/0x30 fs/sysfs/group.c:175
 netdev_queue_add_kobject net/core/net-sysfs.c:1672 [inline]
 netdev_queue_update_kobjects+0x1b4/0x3e0 net/core/net-sysfs.c:1711
 register_queue_kobjects net/core/net-sysfs.c:1772 [inline]
 netdev_register_kobject+0x270/0x320 net/core/net-sysfs.c:2018
 register_netdevice+0x1133/0x1720 net/core/dev.c:10332
 register_netdev+0x3c/0x50 net/core/dev.c:10456
 ip6gre_init_net+0x251/0x320 net/ipv6/ip6_gre.c:1621
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1364 [inline]
 free_pcp_prepare+0x448/0x450 mm/page_alloc.c:1435
 free_unref_page_prepare mm/page_alloc.c:3433 [inline]
 free_unref_page_list+0x16a/0xad0 mm/page_alloc.c:3554
 release_pages+0xf3e/0xf90 mm/swap.c:1010
 free_pages_and_swap_cache+0x97/0xb0 mm/swap_state.c:320
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:242 [inline]
 tlb_flush_mmu+0x860/0xa00 mm/mmu_gather.c:249
 tlb_finish_mmu+0xd2/0x1f0 mm/mmu_gather.c:340
 exit_mmap+0x46e/0x7a0 mm/mmap.c:3202
 __mmput+0x95/0x300 kernel/fork.c:1162
 mmput+0x50/0x60 kernel/fork.c:1184
 exit_mm+0x50d/0x760 kernel/exit.c:504
 do_exit+0x63c/0x24d0 kernel/exit.c:815
 do_group_exit+0x13a/0x300 kernel/exit.c:925
 get_signal+0x77e/0x1600 kernel/signal.c:2890
 arch_do_signal_or_restart+0x9f/0x670 arch/x86/kernel/signal.c:865
 handle_signal_work kernel/entry/common.c:148 [inline]
 exit_to_user_mode_loop+0xd4/0x110 kernel/entry/common.c:172
 exit_to_user_mode_prepare kernel/entry/common.c:207 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
 syscall_exit_to_user_mode+0x79/0xc0 kernel/entry/common.c:300

Memory state around the buggy address:
 ffff88811677f280: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
 ffff88811677f300: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb
>ffff88811677f380: fb fb fb fb fb fc fc fc fc fc fc fc fc fa fb fb
                                                          ^
 ffff88811677f400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
 ffff88811677f480: fc fc fc fc fc fc fa fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (2):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets Title
ci2-android-5-15 2022/12/29 18:08 android13-5.15-lts c73b4619ad86 44712fbc .config console log report info [disk image] [vmlinux] [kernel image] KASAN: use-after-free Read in kernfs_get
ci2-android-5-15 2022/10/18 19:43 android13-5.15-lts 44b8b2ac1d96 b31320fc .config console log report info [disk image] [vmlinux] KASAN: use-after-free Read in kernfs_get
* Struck through repros no longer work on HEAD.