[Android 6.1] KASAN: use-after-free Read in get_max_inline_xattr_value_size

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a24911abfd55 ANDROID: Update symbol for Exynos SoC
git tree: android14-6.1
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1457f142a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=b75c7b7ab5a09aff
dashboard link: https://syzkaller.appspot.com/bug?extid=4307d88364336839639e
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=15774f96a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10da132ea80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ebbd9c5d620c/disk-a24911ab.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/91631c1e2a1a/vmlinux-a24911ab.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ec5213f3f38d/bzImage-a24911ab.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/067fb9de89cf/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4307d8...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 2048
EXT4-fs (loop0): mounted filesystem without journal. Quota mode: none.
EXT4-fs error (device loop0): ext4_xattr_ibody_get:619: inode #18: comm syz-executor289: corrupted in-inode xattr
==================================================================
BUG: KASAN: use-after-free in get_max_inline_xattr_value_size+0x36e/0x510 fs/ext4/inline.c:62
Read of size 4 at addr ffff888121308004 by task syz-executor289/312

CPU: 1 PID: 312 Comm: syz-executor289 Not tainted 6.1.25-syzkaller-00027-ga24911abfd55 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:316 [inline]
print_report+0x158/0x4e0 mm/kasan/report.c:427
kasan_report+0x13c/0x170 mm/kasan/report.c:531
__asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:350
get_max_inline_xattr_value_size+0x36e/0x510 fs/ext4/inline.c:62
ext4_get_max_inline_size+0x13d/0x1f0 fs/ext4/inline.c:113
ext4_try_to_write_inline_data+0xd3/0x1420 fs/ext4/inline.c:663
ext4_write_begin+0x200/0xfb0 fs/ext4/inode.c:1179
ext4_da_write_begin+0x2ff/0x920 fs/ext4/inode.c:2987
generic_perform_write+0x2f9/0x5c0 mm/filemap.c:3765
ext4_buffered_write_iter+0x360/0x640 fs/ext4/file.c:285
ext4_file_write_iter+0x194/0x1cf0
call_write_iter include/linux/fs.h:2215 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x8d1/0xe80 fs/read_write.c:584
ksys_write+0x199/0x2c0 fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__x64_sys_write+0x7b/0x90 fs/read_write.c:646
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fc74bc54329
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 18 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdb248cf38 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fc74bc54329
RDX: 0000000000000001 RSI: 0000000020000280 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 431bde82d7b634db R15: 00007ffdb248cfa0
</TASK>

The buggy address belongs to the physical page:
page:ffffea000484c200 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x121308
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea000484c248 ffffea000484c948 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 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 306, tgid 306 (syz-executor289), ts 24774942178, free_ts 24859714760
set_page_owner include/linux/page_owner.h:33 [inline]
post_alloc_hook+0x213/0x220 mm/page_alloc.c:2581
prep_new_page mm/page_alloc.c:2588 [inline]
get_page_from_freelist+0x276c/0x2850 mm/page_alloc.c:4385
__alloc_pages+0x3a1/0x780 mm/page_alloc.c:5662
__folio_alloc+0x15/0x40 mm/page_alloc.c:5694
__folio_alloc_node include/linux/gfp.h:245 [inline]
folio_alloc include/linux/gfp.h:274 [inline]
shmem_alloc_folio mm/shmem.c:1578 [inline]
shmem_alloc_and_acct_folio+0x78c/0xa50 mm/shmem.c:1603
shmem_get_folio_gfp+0x12d4/0x24b0 mm/shmem.c:1931
shmem_get_folio mm/shmem.c:2062 [inline]
shmem_write_begin+0x164/0x3a0 mm/shmem.c:2550
generic_perform_write+0x2f9/0x5c0 mm/filemap.c:3765
__generic_file_write_iter+0x174/0x3a0 mm/filemap.c:3893
generic_file_write_iter+0xb1/0x310 mm/filemap.c:3925
call_write_iter include/linux/fs.h:2215 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x8d1/0xe80 fs/read_write.c:584
ksys_write+0x199/0x2c0 fs/read_write.c:637
__do_sys_write fs/read_write.c:649 [inline]
__se_sys_write fs/read_write.c:646 [inline]
__x64_sys_write+0x7b/0x90 fs/read_write.c:646
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
reset_page_owner include/linux/page_owner.h:26 [inline]
free_pages_prepare mm/page_alloc.c:1493 [inline]
free_pcp_prepare mm/page_alloc.c:1567 [inline]
free_unref_page_prepare+0x83d/0x850 mm/page_alloc.c:3484
free_unref_page_list+0xf6/0x6c0 mm/page_alloc.c:3626
release_pages+0xf7f/0xfe0 mm/swap.c:1055
__pagevec_release+0x84/0x100 mm/swap.c:1075
pagevec_release include/linux/pagevec.h:71 [inline]
folio_batch_release include/linux/pagevec.h:135 [inline]
shmem_undo_range+0x609/0x15b0 mm/shmem.c:949
shmem_truncate_range mm/shmem.c:1048 [inline]
shmem_evict_inode+0x25f/0xa30 mm/shmem.c:1157
evict+0x2a3/0x630 fs/inode.c:664
iput_final fs/inode.c:1747 [inline]
iput+0x642/0x870 fs/inode.c:1773
dentry_unlink_inode+0x34f/0x440 fs/dcache.c:401
__dentry_kill+0x447/0x650 fs/dcache.c:607
dentry_kill+0xc0/0x2a0
dput+0x160/0x310 fs/dcache.c:913
__fput+0x5f0/0x870 fs/file_table.c:328
____fput+0x15/0x20 fs/file_table.c:348
task_work_run+0x24d/0x2e0 kernel/task_work.c:179
ptrace_notify+0x29e/0x350 kernel/signal.c:2357

Memory state around the buggy address:
ffff888121307f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888121307f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888121308000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff888121308080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888121308100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs error (device loop0): ext4_read_block_bitmap_nowait:438: comm syz-executor289: Invalid block bitmap block 4294967295 in block_group 0


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[syzbot]

syzbot suspects this issue was fixed by commit:

commit 1d2caddbeeee56fbbc36b428c5b909c3ad88eb7f
Author: Theodore Ts'o <ty...@mit.edu>
Date: Fri May 12 19:11:02 2023 +0000

ext4: add bounds checking in get_max_inline_xattr_value_size()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=109e7420e80000
start commit: a24911abfd55 ANDROID: Update symbol for Exynos SoC
git tree: android14-6.1

kernel config: https://syzkaller.appspot.com/x/.config?x=b75c7b7ab5a09aff
dashboard link: https://syzkaller.appspot.com/bug?extid=4307d88364336839639e

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15774f96a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10da132ea80000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: ext4: add bounds checking in get_max_inline_xattr_value_size()

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.