[moderation] [fs?] KASAN: use-after-free Read in sysv_new_inode (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fec50db7033e Linux 6.9-rc3
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15ae4f8d180000
kernel config: https://syzkaller.appspot.com/x/.config?x=c224a427bd88059
dashboard link: https://syzkaller.appspot.com/bug?extid=9ed0a70ae2fec439d528
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-fec50db7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5e63714293fb/vmlinux-fec50db7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4be8125de692/bzImage-fec50db7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9ed0a7...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in sysv_new_inode+0xed4/0x1190 fs/sysv/ialloc.c:153
Read of size 2 at addr ffff88803cc941ce by task syz-executor.3/10932

CPU: 0 PID: 10932 Comm: syz-executor.3 Not tainted 6.9.0-rc3-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0xc3/0x620 mm/kasan/report.c:488
kasan_report+0xd9/0x110 mm/kasan/report.c:601
sysv_new_inode+0xed4/0x1190 fs/sysv/ialloc.c:153
sysv_mknod fs/sysv/namei.c:53 [inline]
sysv_create+0x20/0xf0 fs/sysv/namei.c:67
lookup_open.isra.0+0x10a1/0x13c0 fs/namei.c:3497
open_last_lookups fs/namei.c:3566 [inline]
path_openat+0x92f/0x2990 fs/namei.c:3796
do_filp_open+0x1dc/0x430 fs/namei.c:3826
do_sys_openat2+0x17a/0x1e0 fs/open.c:1406
do_sys_open fs/open.c:1421 [inline]
__do_sys_creat fs/open.c:1497 [inline]
__se_sys_creat fs/open.c:1491 [inline]
__x64_sys_creat+0xcd/0x120 fs/open.c:1491
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x72/0x7a
RIP: 0033:0x7f552187de69
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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:00007f55225440c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007f55219ac050 RCX: 00007f552187de69
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000440
RBP: 00007f55218ca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f55219ac050 R15: 00007ffd41ddadc8
</TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x3cc94
flags: 0xfff80000000000(node=0|zone=1|lastcpupid=0xfff)
page_type: 0xffffffff()
raw: 00fff80000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x100cca(GFP_HIGHUSER_MOVABLE), pid 11325, tgid 11324 (syz-executor.3), ts 298644282239, free_ts 298951393779
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x2d4/0x350 mm/page_alloc.c:1534
prep_new_page mm/page_alloc.c:1541 [inline]
get_page_from_freelist+0xa28/0x3780 mm/page_alloc.c:3317
__alloc_pages+0x22b/0x2460 mm/page_alloc.c:4575
alloc_pages_mpol+0x275/0x610 mm/mempolicy.c:2264
shmem_alloc_folio+0x114/0x150 mm/shmem.c:1634
shmem_alloc_and_add_folio+0x14f/0x6f0 mm/shmem.c:1674
shmem_get_folio_gfp+0x685/0x13e0 mm/shmem.c:2061
shmem_get_folio mm/shmem.c:2166 [inline]
shmem_write_begin+0x15a/0x370 mm/shmem.c:2750
generic_perform_write+0x272/0x620 mm/filemap.c:3974
shmem_file_write_iter+0x114/0x140 mm/shmem.c:2926
call_write_iter include/linux/fs.h:2110 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0x6db/0x1100 fs/read_write.c:590
ksys_write+0x12f/0x260 fs/read_write.c:643
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x72/0x7a
page last free pid 11325 tgid 11324 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+0x527/0xb10 mm/page_alloc.c:2347
free_unref_folios+0x256/0xad0 mm/page_alloc.c:2536
folios_put_refs+0x49c/0x750 mm/swap.c:1034
folio_batch_release include/linux/pagevec.h:101 [inline]
shmem_undo_range+0x5a1/0x1170 mm/shmem.c:1011
shmem_truncate_range mm/shmem.c:1120 [inline]
shmem_evict_inode+0x3a3/0xbb0 mm/shmem.c:1248
evict+0x2ed/0x6c0 fs/inode.c:667
iput_final fs/inode.c:1741 [inline]
iput.part.0+0x5a8/0x7f0 fs/inode.c:1767
iput+0x5c/0x80 fs/inode.c:1757
dentry_unlink_inode+0x295/0x440 fs/dcache.c:400
__dentry_kill+0x1d0/0x600 fs/dcache.c:603
dput.part.0+0x4b1/0x9b0 fs/dcache.c:845
dput+0x1f/0x30 fs/dcache.c:835
__fput+0x3bc/0xb80 fs/file_table.c:430
__fput_sync+0x47/0x50 fs/file_table.c:507
__do_sys_close fs/open.c:1556 [inline]
__se_sys_close fs/open.c:1541 [inline]
__x64_sys_close+0x86/0x100 fs/open.c:1541
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd2/0x260 arch/x86/entry/common.c:83

Memory state around the buggy address:
ffff88803cc94080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88803cc94100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88803cc94180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88803cc94200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88803cc94280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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