Re: [f2fs-dev] [syzbot] [f2fs?] KASAN: slab-use-after-free Read in sanity_check_extent_cache

From: Chao Yu
Date: Thu May 30 2024 - 21:39:49 EST


#syz test: https://git.kernel.org/pub/scm/linux/kernel/git/chao/linux.git wip

On 2024/4/30 2:44, syzbot wrote:
Hello,

syzbot found the following issue on:

HEAD commit: e67572cd2204 Linux 6.9-rc6
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13724f0f180000
kernel config: https://syzkaller.appspot.com/x/.config?x=d2f00edef461175
dashboard link: https://syzkaller.appspot.com/bug?extid=74ebe2104433e9dc610d
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16938440980000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13ae8517180000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/526d150815dd/disk-e67572cd.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/03cba3db92e8/vmlinux-e67572cd.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ec3f54fc8985/bzImage-e67572cd.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/21aa65da230a/mount_0.gz

The issue was bisected to:

commit a53936361330e4c55c0654605178281387d9c761
Author: Chao Yu <chao@xxxxxxxxxx>
Date: Sun Dec 10 09:20:35 2023 +0000

f2fs: delete obsolete FI_FIRST_BLOCK_WRITTEN

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11b78440980000
final oops: https://syzkaller.appspot.com/x/report.txt?x=13b78440980000
console output: https://syzkaller.appspot.com/x/log.txt?x=15b78440980000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+74ebe2104433e9dc610d@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: a53936361330 ("f2fs: delete obsolete FI_FIRST_BLOCK_WRITTEN")

R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3b853316dc
R13: 00007f3b852f8160 R14: 0030656c69662f2e R15: 00007ffdc8faca88
</TASK>
==================================================================
BUG: KASAN: slab-use-after-free in sanity_check_extent_cache+0x370/0x410 fs/f2fs/extent_cache.c:46
Read of size 4 at addr ffff8880739ab220 by task syz-executor200/5097

CPU: 0 PID: 5097 Comm: syz-executor200 Not tainted 6.9.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x169/0x550 mm/kasan/report.c:488
kasan_report+0x143/0x180 mm/kasan/report.c:601
sanity_check_extent_cache+0x370/0x410 fs/f2fs/extent_cache.c:46
do_read_inode fs/f2fs/inode.c:509 [inline]
f2fs_iget+0x33e1/0x46e0 fs/f2fs/inode.c:560
f2fs_nfs_get_inode+0x74/0x100 fs/f2fs/super.c:3237
generic_fh_to_dentry+0x9f/0xf0 fs/libfs.c:1413
exportfs_decode_fh_raw+0x152/0x5f0 fs/exportfs/expfs.c:444
exportfs_decode_fh+0x3c/0x80 fs/exportfs/expfs.c:584
do_handle_to_path fs/fhandle.c:155 [inline]
handle_to_path fs/fhandle.c:210 [inline]
do_handle_open+0x495/0x650 fs/fhandle.c:226
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3b852ab889
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 91 1b 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f3b85239228 EFLAGS: 00000246 ORIG_RAX: 0000000000000130
RAX: ffffffffffffffda RBX: 00007f3b853316d8 RCX: 00007f3b852ab889
RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000004
RBP: 00007f3b853316d0 R08: 00007ffdc8faca87 R09: 00007f3b852396c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f3b853316dc
R13: 00007f3b852f8160 R14: 0030656c69662f2e R15: 00007ffdc8faca88
</TASK>

Allocated by task 5092:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
unpoison_slab_object mm/kasan/common.c:312 [inline]
__kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:338
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slub.c:3798 [inline]
slab_alloc_node mm/slub.c:3845 [inline]
kmem_cache_alloc+0x174/0x340 mm/slub.c:3852
f2fs_kmem_cache_alloc_nofail fs/f2fs/f2fs.h:2817 [inline]
f2fs_kmem_cache_alloc fs/f2fs/f2fs.h:2827 [inline]
__grab_extent_tree+0x183/0x400 fs/f2fs/extent_cache.c:334
f2fs_init_read_extent_tree+0x455/0x910 fs/f2fs/extent_cache.c:405
do_read_inode fs/f2fs/inode.c:506 [inline]
f2fs_iget+0x33d1/0x46e0 fs/f2fs/inode.c:560
f2fs_nfs_get_inode+0x74/0x100 fs/f2fs/super.c:3237
generic_fh_to_dentry+0x9f/0xf0 fs/libfs.c:1413
exportfs_decode_fh_raw+0x152/0x5f0 fs/exportfs/expfs.c:444
exportfs_decode_fh+0x3c/0x80 fs/exportfs/expfs.c:584
do_handle_to_path fs/fhandle.c:155 [inline]
handle_to_path fs/fhandle.c:210 [inline]
do_handle_open+0x495/0x650 fs/fhandle.c:226
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5092:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
poison_slab_object+0xa6/0xe0 mm/kasan/common.c:240
__kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2106 [inline]
slab_free mm/slub.c:4280 [inline]
kmem_cache_free+0x10b/0x2c0 mm/slub.c:4344
__destroy_extent_tree+0x307/0x600 fs/f2fs/extent_cache.c:1132
f2fs_destroy_extent_tree+0x17/0x30 fs/f2fs/extent_cache.c:1143
f2fs_evict_inode+0x44d/0x1550 fs/f2fs/inode.c:831
evict+0x2a8/0x630 fs/inode.c:667
f2fs_iget+0x1a68/0x46e0 fs/f2fs/inode.c:621
f2fs_nfs_get_inode+0x74/0x100 fs/f2fs/super.c:3237
generic_fh_to_dentry+0x9f/0xf0 fs/libfs.c:1413
exportfs_decode_fh_raw+0x152/0x5f0 fs/exportfs/expfs.c:444
exportfs_decode_fh+0x3c/0x80 fs/exportfs/expfs.c:584
do_handle_to_path fs/fhandle.c:155 [inline]
handle_to_path fs/fhandle.c:210 [inline]
do_handle_open+0x495/0x650 fs/fhandle.c:226
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880739ab1a0
which belongs to the cache f2fs_extent_tree of size 144
The buggy address is located 128 bytes inside of
freed 144-byte region [ffff8880739ab1a0, ffff8880739ab230)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x739ab
flags: 0xfff80000000800(slab|node=0|zone=1|lastcpupid=0xfff)
page_type: 0xffffffff()
raw: 00fff80000000800 ffff88801afb08c0 dead000000000122 0000000000000000
raw: 0000000000000000 0000000080130013 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Reclaimable, gfp_mask 0x12c50(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_RECLAIMABLE), pid 5076, tgid -326355158 (syz-executor200), ts 5083, free_ts 26740999480
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1534
prep_new_page mm/page_alloc.c:1541 [inline]
get_page_from_freelist+0x3410/0x35b0 mm/page_alloc.c:3317
__alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575
__alloc_pages_node include/linux/gfp.h:238 [inline]
alloc_pages_node include/linux/gfp.h:261 [inline]
alloc_slab_page+0x5f/0x160 mm/slub.c:2175
allocate_slab mm/slub.c:2338 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2391
___slab_alloc+0xc73/0x1260 mm/slub.c:3525
__slab_alloc mm/slub.c:3610 [inline]
__slab_alloc_node mm/slub.c:3663 [inline]
slab_alloc_node mm/slub.c:3835 [inline]
kmem_cache_alloc+0x252/0x340 mm/slub.c:3852
f2fs_kmem_cache_alloc_nofail fs/f2fs/f2fs.h:2817 [inline]
f2fs_kmem_cache_alloc fs/f2fs/f2fs.h:2827 [inline]
__grab_extent_tree+0x183/0x400 fs/f2fs/extent_cache.c:334
f2fs_init_read_extent_tree+0x455/0x910 fs/f2fs/extent_cache.c:405
do_read_inode fs/f2fs/inode.c:506 [inline]
f2fs_iget+0x33d1/0x46e0 fs/f2fs/inode.c:560
f2fs_nfs_get_inode+0x74/0x100 fs/f2fs/super.c:3237
generic_fh_to_dentry+0x9f/0xf0 fs/libfs.c:1413
exportfs_decode_fh_raw+0x152/0x5f0 fs/exportfs/expfs.c:444
exportfs_decode_fh+0x3c/0x80 fs/exportfs/expfs.c:584
do_handle_to_path fs/fhandle.c:155 [inline]
handle_to_path fs/fhandle.c:210 [inline]
do_handle_open+0x495/0x650 fs/fhandle.c:226
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
page last free pid 1 tgid 1 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1141 [inline]
free_unref_page_prepare+0x97b/0xaa0 mm/page_alloc.c:2347
free_unref_page+0x37/0x3f0 mm/page_alloc.c:2487
free_contig_range+0x9e/0x160 mm/page_alloc.c:6572
destroy_args+0x8a/0x890 mm/debug_vm_pgtable.c:1036
debug_vm_pgtable+0x4be/0x550 mm/debug_vm_pgtable.c:1416
do_one_initcall+0x248/0x880 init/main.c:1245
do_initcall_level+0x157/0x210 init/main.c:1307
do_initcalls+0x3f/0x80 init/main.c:1323
kernel_init_freeable+0x435/0x5d0 init/main.c:1555
kernel_init+0x1d/0x2b0 init/main.c:1444
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Memory state around the buggy address:
ffff8880739ab100: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff8880739ab180: fc fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb
ffff8880739ab200: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
^
ffff8880739ab280: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8880739ab300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.

syzbot will keep track of this issue. See:
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup


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