[syzbot] [btrfs?] KASAN: use-after-free Read in wait_subpage_spinlock

From: syzbot
Date: Mon Jan 02 2023 - 05:02:51 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 1b929c02afd3 Linux 6.2-rc1
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=170cedb0480000
kernel config: https://syzkaller.appspot.com/x/.config?x=2651619a26b4d687
dashboard link: https://syzkaller.appspot.com/bug?extid=042fc0183073dc434e78
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: i386

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+042fc0183073dc434e78@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KASAN: use-after-free in btrfs_sb fs/btrfs/super.h:14 [inline]
BUG: KASAN: use-after-free in wait_subpage_spinlock+0x1be/0x210 fs/btrfs/inode.c:8232
Read of size 8 at addr ffff888076b74678 by task syz-executor.1/31086

CPU: 0 PID: 31086 Comm: syz-executor.1 Not tainted 6.2.0-rc1-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:306 [inline]
print_report+0x15e/0x45d mm/kasan/report.c:417
kasan_report+0xbf/0x1f0 mm/kasan/report.c:517
btrfs_sb fs/btrfs/super.h:14 [inline]
wait_subpage_spinlock+0x1be/0x210 fs/btrfs/inode.c:8232
__btrfs_release_folio fs/btrfs/inode.c:8261 [inline]
btrfs_release_folio+0x109/0x130 fs/btrfs/inode.c:8271
filemap_release_folio+0x13f/0x1b0 mm/filemap.c:3967
shrink_folio_list+0x1ea9/0x3a60 mm/vmscan.c:2000
shrink_inactive_list mm/vmscan.c:2526 [inline]
shrink_list mm/vmscan.c:2767 [inline]
shrink_lruvec+0xd0e/0x27a0 mm/vmscan.c:5951
shrink_node_memcgs mm/vmscan.c:6138 [inline]
shrink_node+0x8f2/0x1f40 mm/vmscan.c:6169
shrink_zones mm/vmscan.c:6407 [inline]
do_try_to_free_pages+0x3b4/0x17a0 mm/vmscan.c:6469
try_to_free_pages+0x2e5/0x960 mm/vmscan.c:6704
__perform_reclaim mm/page_alloc.c:4750 [inline]
__alloc_pages_direct_reclaim mm/page_alloc.c:4772 [inline]
__alloc_pages_slowpath.constprop.0+0x8b6/0x23d0 mm/page_alloc.c:5178
__alloc_pages+0x4aa/0x5b0 mm/page_alloc.c:5562
__alloc_pages_node include/linux/gfp.h:237 [inline]
alloc_pages_node include/linux/gfp.h:260 [inline]
bpf_ringbuf_area_alloc kernel/bpf/ringbuf.c:130 [inline]
bpf_ringbuf_alloc kernel/bpf/ringbuf.c:167 [inline]
ringbuf_map_alloc kernel/bpf/ringbuf.c:207 [inline]
ringbuf_map_alloc+0x2a9/0x7d0 kernel/bpf/ringbuf.c:183
find_and_alloc_map kernel/bpf/syscall.c:131 [inline]
map_create+0x4d3/0x18d0 kernel/bpf/syscall.c:1123
__sys_bpf+0x13b7/0x5000 kernel/bpf/syscall.c:4961
__do_sys_bpf kernel/bpf/syscall.c:5083 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5081 [inline]
__ia32_sys_bpf+0x78/0xe0 kernel/bpf/syscall.c:5081
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
entry_SYSENTER_compat_after_hwframe+0x70/0x82
RIP: 0023:0xf7ff8549
Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f7ff35cc EFLAGS: 00000296
ORIG_RAX: 0000000000000165
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000200004c0
RDX: 0000000000000048 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>

Allocated by task 31068:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:371 [inline]
____kasan_kmalloc mm/kasan/common.c:330 [inline]
__kasan_kmalloc+0xa5/0xb0 mm/kasan/common.c:380
kasan_kmalloc include/linux/kasan.h:211 [inline]
__do_kmalloc_node mm/slab_common.c:968 [inline]
__kmalloc+0x5a/0xd0 mm/slab_common.c:981
kmalloc include/linux/slab.h:584 [inline]
tomoyo_realpath_from_path+0xc3/0x600 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_number_perm+0x217/0x570 security/tomoyo/file.c:723
security_file_ioctl+0x54/0xb0 security/security.c:1624
__do_compat_sys_ioctl+0x4e/0x2b0 fs/ioctl.c:920
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
entry_SYSENTER_compat_after_hwframe+0x70/0x82

Freed by task 31068:
kasan_save_stack+0x22/0x40 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
kasan_save_free_info+0x2e/0x40 mm/kasan/generic.c:518
____kasan_slab_free mm/kasan/common.c:236 [inline]
____kasan_slab_free+0x160/0x1c0 mm/kasan/common.c:200
kasan_slab_free include/linux/kasan.h:177 [inline]
slab_free_hook mm/slub.c:1781 [inline]
slab_free_freelist_hook+0x8b/0x1c0 mm/slub.c:1807
slab_free mm/slub.c:3787 [inline]
__kmem_cache_free+0xaf/0x3b0 mm/slub.c:3800
tomoyo_realpath_from_path+0x190/0x600 security/tomoyo/realpath.c:286
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_number_perm+0x217/0x570 security/tomoyo/file.c:723
security_file_ioctl+0x54/0xb0 security/security.c:1624
__do_compat_sys_ioctl+0x4e/0x2b0 fs/ioctl.c:920
do_syscall_32_irqs_on arch/x86/entry/common.c:112 [inline]
__do_fast_syscall_32+0x65/0xf0 arch/x86/entry/common.c:178
do_fast_syscall_32+0x33/0x70 arch/x86/entry/common.c:203
entry_SYSENTER_compat_after_hwframe+0x70/0x82

The buggy address belongs to the object at ffff888076b74000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1656 bytes inside of
4096-byte region [ffff888076b74000, ffff888076b75000)

The buggy address belongs to the physical page:
page:ffffea0001dadc00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x76b70
head:ffffea0001dadc00 order:3 compound_mapcount:0 subpages_mapcount:0 compound_pincount:0
anon flags: 0x4fff00000010200(slab|head|node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000010200 ffff888012443040 0000000000000000 0000000000000001
raw: 0000000000000000 0000000000040004 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 0x1d2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 4589, tgid 4589 (udevd), ts 844464905092, free_ts 844431282822
prep_new_page mm/page_alloc.c:2531 [inline]
get_page_from_freelist+0x119c/0x2ce0 mm/page_alloc.c:4283
__alloc_pages+0x1cb/0x5b0 mm/page_alloc.c:5549
alloc_pages+0x1aa/0x270 mm/mempolicy.c:2286
alloc_slab_page mm/slub.c:1851 [inline]
allocate_slab+0x25f/0x350 mm/slub.c:1998
new_slab mm/slub.c:2051 [inline]
___slab_alloc+0xa91/0x1400 mm/slub.c:3193
__slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3292
__slab_alloc_node mm/slub.c:3345 [inline]
slab_alloc_node mm/slub.c:3442 [inline]
__kmem_cache_alloc_node+0x1a4/0x430 mm/slub.c:3491
__do_kmalloc_node mm/slab_common.c:967 [inline]
__kmalloc+0x4a/0xd0 mm/slab_common.c:981
kmalloc include/linux/slab.h:584 [inline]
tomoyo_realpath_from_path+0xc3/0x600 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_check_open_permission+0x297/0x3a0 security/tomoyo/file.c:771
tomoyo_file_open security/tomoyo/tomoyo.c:332 [inline]
tomoyo_file_open+0xa1/0xc0 security/tomoyo/tomoyo.c:327
security_file_open+0x49/0xb0 security/security.c:1718
do_dentry_open+0x575/0x13f0 fs/open.c:869
do_open fs/namei.c:3557 [inline]
path_openat+0x1bbc/0x2a50 fs/namei.c:3714
do_filp_open+0x1ba/0x410 fs/namei.c:3741
do_sys_openat2+0x16d/0x4c0 fs/open.c:1310
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+0x65c/0xc00 mm/page_alloc.c:1496
free_unref_page_prepare mm/page_alloc.c:3369 [inline]
free_unref_page+0x1d/0x490 mm/page_alloc.c:3464
__unfreeze_partials+0x17c/0x1a0 mm/slub.c:2637
qlink_free mm/kasan/quarantine.c:168 [inline]
qlist_free_all+0x6a/0x170 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x192/0x220 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0x66/0x90 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+0x1e4/0x430 mm/slub.c:3476
kmem_cache_zalloc include/linux/slab.h:710 [inline]
jbd2_alloc_handle include/linux/jbd2.h:1596 [inline]
new_handle fs/jbd2/transaction.c:476 [inline]
jbd2__journal_start+0x195/0x9b0 fs/jbd2/transaction.c:503
__ext4_journal_start_sb+0x6e9/0x860 fs/ext4/ext4_jbd2.c:111
__ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
ext4_dirty_inode+0xa5/0x130 fs/ext4/inode.c:6107
__mark_inode_dirty+0x247/0x11e0 fs/fs-writeback.c:2419
mark_inode_dirty include/linux/fs.h:2462 [inline]
generic_write_end+0x354/0x440 fs/buffer.c:2184
ext4_da_write_end+0x1f5/0xa30 fs/ext4/inode.c:3175
generic_perform_write+0x316/0x570 mm/filemap.c:3783
ext4_buffered_write_iter+0x15b/0x460 fs/ext4/file.c:285
ext4_file_write_iter+0x8bf/0x1710 fs/ext4/file.c:700

Memory state around the buggy address:
ffff888076b74500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888076b74580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888076b74600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888076b74680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888076b74700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
----------------
Code disassembly (best guess):
0: 03 74 c0 01 add 0x1(%rax,%rax,8),%esi
4: 10 05 03 74 b8 01 adc %al,0x1b87403(%rip) # 0x1b8740d
a: 10 06 adc %al,(%rsi)
c: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi
10: 10 07 adc %al,(%rdi)
12: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi
16: 10 08 adc %cl,(%rax)
18: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi
1c: 00 00 add %al,(%rax)
1e: 00 00 add %al,(%rax)
20: 00 51 52 add %dl,0x52(%rcx)
23: 55 push %rbp
24: 89 e5 mov %esp,%ebp
26: 0f 34 sysenter
28: cd 80 int $0x80
* 2a: 5d pop %rbp <-- trapping instruction
2b: 5a pop %rdx
2c: 59 pop %rcx
2d: c3 retq
2e: 90 nop
2f: 90 nop
30: 90 nop
31: 90 nop
32: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi
39: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi

---
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