KASAN: null-ptr-deref Read in filp_close (2)

Status: fixed on 2021/11/10 13:22
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+283ce5a46486d6acdbaf@syzkaller.appspotmail.com
Fix commit: 3b0462726e7e cgroup: verify that source is a string 9b5b872215fe file: fix close_range() for unshare+cloexec
First crash: 1957d, last: 1845d
▶ ▼ Discussions (9)
Title Replies (including bot) Last reply
[PATCH 5.10 000/243] 5.10.52-rc1 review 254 (254) 2021/07/21 15:19
[PATCH 5.13 000/351] 5.13.4-rc1 review 353 (353) 2021/07/19 19:32
[PATCH 5.4 000/149] 5.4.134-rc1 review 152 (152) 2021/07/19 17:46
[PATCH 5.12 000/292] 5.12.19-rc1 review 294 (294) 2021/07/19 17:28
[syzbot] KASAN: null-ptr-deref Read in filp_close (2) 10 (15) 2021/07/14 14:16
[PATCH 1/2] cgroup: verify that source is a string 2 (2) 2021/07/14 13:47
[PATCH 5.11 000/210] 5.11.14-rc1 review 214 (214) 2021/04/13 04:46
[PATCH 1/3] file: fix close_range() for unshare+cloexec 1 (1) 2021/04/02 12:35
Re: [syzbot] KASAN: null-ptr-deref Read in filp_close (2) 5 (5) 2021/03/29 17:35
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: null-ptr-deref Read in filp_close fs 11 syz, C done 9 2050d 2052d 19/29 fixed on 2021/03/10 01:48
upstream KASAN: use-after-free Read in filp_close io-uring fs 19 syz, C done 17 1295d 1523d 22/29 fixed on 2023/02/24 13:50
android-54 KASAN: use-after-free Read in filp_close 19 syz, C 3 1822d 2027d 0/2 auto-obsoleted due to no activity on 2023/04/21 02:05
android-5-10 general protection fault in filp_close 2 1 1225d 1225d 0/2 auto-obsoleted due to no activity on 2023/06/22 23:34
android-5-15 general protection fault in filp_close 2 1 107d 107d 0/2 auto-obsoleted due to no activity on 2026/07/14 19:12
▶ ▼ Last patch testing requests (2)
Created Duration User Patch Repo Result
2021/07/14 13:58 16m christian.brauner@ubuntu.com https://gitlab.com/brauner/linux.git 595fac5cecba71935450ec431eb8dfa963cf45fe OK
2021/07/14 13:52 1m christian.brauner@ubuntu.com https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/ 595fac5cecba71935450ec431eb8dfa963cf45fe error

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in instrument_atomic_read include/linux/instrumented.h:71 [inline]
BUG: KASAN: use-after-free in atomic64_read include/asm-generic/atomic-instrumented.h:605 [inline]
BUG: KASAN: use-after-free in atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
BUG: KASAN: use-after-free in filp_close+0x22/0x170 fs/open.c:1306
Read of size 8 at addr ffff888025a40a78 by task syz-executor493/8445

CPU: 1 PID: 8445 Comm: syz-executor493 Not tainted 5.14.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 print_address_description.constprop.0.cold+0x6c/0x309 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report.cold+0x83/0xdf mm/kasan/report.c:436
 check_region_inline mm/kasan/generic.c:183 [inline]
 kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
 instrument_atomic_read include/linux/instrumented.h:71 [inline]
 atomic64_read include/asm-generic/atomic-instrumented.h:605 [inline]
 atomic_long_read include/asm-generic/atomic-long.h:29 [inline]
 filp_close+0x22/0x170 fs/open.c:1306
 close_fd+0x5c/0x80 fs/file.c:628
 __do_sys_close fs/open.c:1331 [inline]
 __se_sys_close fs/open.c:1329 [inline]
 __x64_sys_close+0x2f/0xa0 fs/open.c:1329
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x4021b3
Code: c7 c2 c0 ff ff ff f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb ba 0f 1f 00 64 8b 04 25 18 00 00 00 85 c0 75 14 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8
RSP: 002b:00007ffe62cc73e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 00000000004021b3
RDX: 0000000020000000 RSI: 0000000000000005 RDI: 0000000000000004
RBP: 00007ffe62cc73f8 R08: 0000000000000004 R09: 00000000004aa000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe62cc7400
R13: 0000000000000000 R14: 00000000004ad018 R15: 0000000000400488

Allocated by task 8445:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 __kasan_slab_alloc+0x84/0xa0 mm/kasan/common.c:467
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slab.h:512 [inline]
 slab_alloc_node mm/slub.c:2981 [inline]
 slab_alloc mm/slub.c:2989 [inline]
 kmem_cache_alloc+0x216/0x3a0 mm/slub.c:2994
 kmem_cache_zalloc include/linux/slab.h:711 [inline]
 __alloc_file+0x21/0x280 fs/file_table.c:101
 alloc_empty_file+0x6d/0x170 fs/file_table.c:150
 path_openat+0xde/0x27f0 fs/namei.c:3493
 do_filp_open+0x1aa/0x400 fs/namei.c:3534
 do_sys_openat2+0x16d/0x420 fs/open.c:1204
 do_sys_open fs/open.c:1220 [inline]
 __do_sys_creat fs/open.c:1294 [inline]
 __se_sys_creat fs/open.c:1288 [inline]
 __x64_sys_creat+0xc9/0x120 fs/open.c:1288
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Freed by task 8445:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_set_track+0x1c/0x30 mm/kasan/common.c:46
 kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:360
 ____kasan_slab_free mm/kasan/common.c:366 [inline]
 ____kasan_slab_free mm/kasan/common.c:328 [inline]
 __kasan_slab_free+0xfb/0x130 mm/kasan/common.c:374
 kasan_slab_free include/linux/kasan.h:229 [inline]
 slab_free_hook mm/slub.c:1650 [inline]
 slab_free_freelist_hook+0xdf/0x240 mm/slub.c:1675
 slab_free mm/slub.c:3235 [inline]
 kfree+0xeb/0x650 mm/slub.c:4295
 put_fs_context+0x3fb/0x650 fs/fs_context.c:454
 fscontext_release+0x4c/0x60 fs/fsopen.c:73
 __fput+0x288/0x920 fs/file_table.c:280
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
 exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348
 __call_rcu kernel/rcu/tree.c:3029 [inline]
 call_rcu+0xb1/0x750 kernel/rcu/tree.c:3109
 task_work_run+0xdd/0x1a0 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
 exit_to_user_mode_prepare+0x27e/0x290 kernel/entry/common.c:209
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:302
 do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Second to last potentially related work creation:
 kasan_save_stack+0x1b/0x40 mm/kasan/common.c:38
 kasan_record_aux_stack+0xe5/0x110 mm/kasan/generic.c:348
 task_work_add+0x3a/0x190 kernel/task_work.c:38
 fput_many.part.0+0xbb/0x170 fs/file_table.c:341
 fput_many fs/file_table.c:336 [inline]
 fput+0x3b/0x50 fs/file_table.c:357
 path_openat+0x19bd/0x27f0 fs/namei.c:3516
 do_filp_open+0x1aa/0x400 fs/namei.c:3534
 do_sys_openat2+0x16d/0x420 fs/open.c:1204
 do_sys_open fs/open.c:1220 [inline]
 __do_sys_open fs/open.c:1228 [inline]
 __se_sys_open fs/open.c:1224 [inline]
 __x64_sys_open+0x119/0x1c0 fs/open.c:1224
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

The buggy address belongs to the object at ffff888025a40a00
 which belongs to the cache filp of size 464
The buggy address is located 120 bytes inside of
 464-byte region [ffff888025a40a00, ffff888025a40bd0)
The buggy address belongs to the page:
page:ffffea0000969000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x25a40
head:ffffea0000969000 order:1 compound_mapcount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 0000000b00000001 ffff8880109c4780
raw: 0000000000000000 00000000800c000c 00000001ffffffff 0000000000000000
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 4875, ts 15466439710, free_ts 15379402342
 prep_new_page mm/page_alloc.c:2433 [inline]
 get_page_from_freelist+0xa72/0x2f80 mm/page_alloc.c:4166
 __alloc_pages+0x1b2/0x500 mm/page_alloc.c:5374
 alloc_pages+0x18c/0x2a0 mm/mempolicy.c:2244
 alloc_slab_page mm/slub.c:1713 [inline]
 allocate_slab+0x32b/0x4c0 mm/slub.c:1853
 new_slab mm/slub.c:1916 [inline]
 new_slab_objects mm/slub.c:2662 [inline]
 ___slab_alloc+0x4ba/0x820 mm/slub.c:2825
 __slab_alloc.constprop.0+0xa7/0xf0 mm/slub.c:2865
 slab_alloc_node mm/slub.c:2947 [inline]
 slab_alloc mm/slub.c:2989 [inline]
 kmem_cache_alloc+0x372/0x3a0 mm/slub.c:2994
 kmem_cache_zalloc include/linux/slab.h:711 [inline]
 __alloc_file+0x21/0x280 fs/file_table.c:101
 alloc_empty_file+0x6d/0x170 fs/file_table.c:150
 path_openat+0xde/0x27f0 fs/namei.c:3493
 do_filp_open+0x1aa/0x400 fs/namei.c:3534
 do_sys_openat2+0x16d/0x420 fs/open.c:1204
 do_sys_open fs/open.c:1220 [inline]
 __do_sys_open fs/open.c:1228 [inline]
 __se_sys_open fs/open.c:1224 [inline]
 __x64_sys_open+0x119/0x1c0 fs/open.c:1224
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1343 [inline]
 free_pcp_prepare+0x2c5/0x780 mm/page_alloc.c:1394
 free_unref_page_prepare mm/page_alloc.c:3329 [inline]
 free_unref_page+0x19/0x690 mm/page_alloc.c:3408
 qlink_free mm/kasan/quarantine.c:146 [inline]
 qlist_free_all+0x5a/0xc0 mm/kasan/quarantine.c:165
 kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:272
 __kasan_slab_alloc+0x8e/0xa0 mm/kasan/common.c:444
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slab.h:512 [inline]
 slab_alloc_node mm/slub.c:2981 [inline]
 slab_alloc mm/slub.c:2989 [inline]
 __kmalloc+0x1f4/0x330 mm/slub.c:4133
 kmalloc include/linux/slab.h:596 [inline]
 tomoyo_add_entry security/tomoyo/common.c:2031 [inline]
 tomoyo_supervisor+0xce8/0xf00 security/tomoyo/common.c:2103
 tomoyo_audit_path_log security/tomoyo/file.c:168 [inline]
 tomoyo_path_permission security/tomoyo/file.c:587 [inline]
 tomoyo_path_permission+0x270/0x3a0 security/tomoyo/file.c:573
 tomoyo_path_perm+0x2f0/0x400 security/tomoyo/file.c:838
 security_inode_getattr+0xcf/0x140 security/security.c:1332
 vfs_getattr fs/stat.c:139 [inline]
 vfs_statx+0x164/0x390 fs/stat.c:207
 vfs_fstatat fs/stat.c:225 [inline]
 vfs_lstat include/linux/fs.h:3386 [inline]
 __do_sys_newlstat+0x91/0x110 fs/stat.c:380
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Memory state around the buggy address:
 ffff888025a40900: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
 ffff888025a40980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888025a40a00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff888025a40a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888025a40b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2021/07/13 04:11 upstream 7fef2edf7cc7 f415556d .config console log report syz C ci-upstream-kasan-gce-root KASAN: use-after-free Read in filp_close
2021/03/22 07:43 upstream 5ee96fa9dd78 bea32f74 .config console log report info ci-upstream-kasan-gce KASAN: null-ptr-deref Read in filp_close
2021/06/28 19:38 upstream 62fb9874f5da 9d2ab5df .config console log report info ci-upstream-kasan-gce-root KASAN: use-after-free Read in filp_close
* Struck through repros no longer work on HEAD.