Re: [syzbot] KASAN: null-ptr-deref Read in filp_close (2)

From: syzbot
Date: Tue Jul 13 2021 - 00:12:22 EST

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syzbot has found a reproducer for the following issue on:

HEAD commit: 7fef2edf sd: don't mess with SD_MINORS for CONFIG_DEBUG_BL..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=178919b0300000
kernel config: https://syzkaller.appspot.com/x/.config?x=20276914ec6ad813
dashboard link: https://syzkaller.appspot.com/bug?extid=283ce5a46486d6acdbaf
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=120220f2300000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=115f37b4300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+283ce5a46486d6acdbaf@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
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
==================================================================

Next message: Paul E. McKenney: "Re: [PATCH] RCU: Fix macro name CONFIG_TASKS_RCU_TRACE"
Previous message: Hridya Valsaraju: "[PATCH v2] dma-buf: Delete the DMA-BUF attachment sysfs statistics"
Next in thread: Linus Torvalds: "Re: [syzbot] KASAN: null-ptr-deref Read in filp_close (2)"
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