[syzbot] [ntfs3?] KASAN: use-after-free Read in bcmp

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8689f4f2ea56 Merge tag 'mmc-v6.5-2' of git://git.kernel.or..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1658af44a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=15873d91ff37a949
dashboard link: https://syzkaller.appspot.com/bug?extid=53ce40c8c0322c06aea5
compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12f82688a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12d54a78a80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c84becffd011/disk-8689f4f2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/cfa539e85d0d/vmlinux-8689f4f2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c60700b69248/bzImage-8689f4f2.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/15e5129dfa97/mount_0.gz

The issue was bisected to:

commit 6a4cd3ea7d771be17177d95ff67d22cfa2a38b50
Author: Konstantin Komarov <almaz.ale...@paragon-software.com>
Date: Mon May 8 07:56:13 2023 +0000

fs/ntfs3: Alternative boot if primary boot is corrupted

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=10346eb0a80000
final oops: https://syzkaller.appspot.com/x/report.txt?x=12346eb0a80000
console output: https://syzkaller.appspot.com/x/log.txt?x=14346eb0a80000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+53ce40...@syzkaller.appspotmail.com
Fixes: 6a4cd3ea7d77 ("fs/ntfs3: Alternative boot if primary boot is corrupted")

ntfs3: loop0: Different NTFS sector size (4096) and media sector size (512).
ntfs3: loop0: RAW NTFS volume: Filesystem size 16384.00 Gb > volume size 0.00 Gb. Mount in read-only.
ntfs3: loop0: NTFS 16384.00 Gb is too big to use 32 bits per cluster.
==================================================================
BUG: KASAN: use-after-free in memcmp lib/string.c:681 [inline]
BUG: KASAN: use-after-free in bcmp+0xc0/0x1e0 lib/string.c:713
Read of size 8 at addr ffff888074005002 by task syz-executor256/5017

CPU: 0 PID: 5017 Comm: syz-executor256 Not tainted 6.4.0-syzkaller-12365-g8689f4f2ea56 #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+0x1e7/0x2d0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0x163/0x540 mm/kasan/report.c:475
kasan_report+0x175/0x1b0 mm/kasan/report.c:588
memcmp lib/string.c:681 [inline]
bcmp+0xc0/0x1e0 lib/string.c:713
ntfs_init_from_boot fs/ntfs3/super.c:860 [inline]
ntfs_fill_super+0x9e6/0x4cb0 fs/ntfs3/super.c:1141
get_tree_bdev+0x468/0x6c0 fs/super.c:1318
vfs_get_tree+0x8c/0x270 fs/super.c:1519
do_new_mount+0x28f/0xae0 fs/namespace.c:3335
do_mount fs/namespace.c:3675 [inline]
__do_sys_mount fs/namespace.c:3884 [inline]
__se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3861
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f08206ada0a
Code: 48 c7 c2 c0 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff eb d2 e8 a8 00 00 00 0f 1f 84 00 00 00 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc5e683e78 EFLAGS: 00000286 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f08206ada0a
RDX: 00000000200000c0 RSI: 0000000020000000 RDI: 00007ffc5e683e90
RBP: 00007ffc5e683e90 R08: 00007ffc5e683ed0 R09: 0000000000000000
R10: 0000000000800000 R11: 0000000000000286 R12: 0000000000000004
R13: 0000555555bbb2c0 R14: 0000000000800000 R15: 00007ffc5e683ed0
</TASK>

The buggy address belongs to the physical page:
page:ffffea0001d00140 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x74005
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 ffffea0001d00188 ffff8880b9843020 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 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO), pid 5017, tgid 5017 (syz-executor256), ts 72917555675, free_ts 72955416955
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1570
prep_new_page mm/page_alloc.c:1577 [inline]
get_page_from_freelist+0x31e8/0x3370 mm/page_alloc.c:3221
__alloc_pages+0x255/0x670 mm/page_alloc.c:4477
__folio_alloc+0x13/0x30 mm/page_alloc.c:4509
vma_alloc_folio+0x48a/0x9a0 mm/mempolicy.c:2240
do_anonymous_page mm/memory.c:4097 [inline]
do_pte_missing mm/memory.c:3662 [inline]
handle_pte_fault mm/memory.c:4932 [inline]
__handle_mm_fault mm/memory.c:5072 [inline]
handle_mm_fault+0x20c7/0x5410 mm/memory.c:5226
do_user_addr_fault arch/x86/mm/fault.c:1343 [inline]
handle_page_fault arch/x86/mm/fault.c:1486 [inline]
exc_page_fault+0x3cf/0x7c0 arch/x86/mm/fault.c:1542
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1161 [inline]
free_unref_page_prepare+0x903/0xa30 mm/page_alloc.c:2348
free_unref_page_list+0x596/0x830 mm/page_alloc.c:2489
release_pages+0x2193/0x2470 mm/swap.c:1042
tlb_batch_pages_flush mm/mmu_gather.c:97 [inline]
tlb_flush_mmu_free mm/mmu_gather.c:292 [inline]
tlb_flush_mmu+0x100/0x210 mm/mmu_gather.c:299
tlb_finish_mmu+0xd4/0x1f0 mm/mmu_gather.c:391
unmap_region+0x258/0x2a0 mm/mmap.c:2313
do_vmi_align_munmap+0x135d/0x1630 mm/mmap.c:2552
do_vmi_munmap+0x24d/0x2d0 mm/mmap.c:2619
__vm_munmap+0x230/0x450 mm/mmap.c:2899
__do_sys_munmap mm/mmap.c:2916 [inline]
__se_sys_munmap mm/mmap.c:2913 [inline]
__x64_sys_munmap+0x69/0x80 mm/mmap.c:2913
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
ffff888074004f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff888074004f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888074005000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff888074005080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff888074005100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


---
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[Pavel Skripkin]

Hi Syzbot,

Syzbot <syzbot+53ce40...@syzkaller.appspotmail.com> says:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 8689f4f2ea56 Merge tag 'mmc-v6.5-2' of git://git.kernel.or..
> git tree: upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=1658af44a80000
> kernel config: https://syzkaller.appspot.com/x/.config?x=15873d91ff37a949
> dashboard link: https://syzkaller.appspot.com/bug?extid=53ce40c8c0322c06aea5
> compiler: Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12f82688a80000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12d54a78a80000
>

#syz test
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master





With regards,
Pavel Skripkin

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+53ce40...@syzkaller.appspotmail.com

Tested on:

commit: eb26cbb1 Merge tag 'platform-drivers-x86-v6.5-2' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=119e1bd4a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=6d0f369ef5fb88c9
dashboard link: https://syzkaller.appspot.com/bug?extid=53ce40c8c0322c06aea5
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
patch: https://syzkaller.appspot.com/x/patch.diff?x=1405dac4a80000

Note: testing is done by a robot and is best-effort only.