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

[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.alexandrovich@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+53ce40c8c0322c06aea5@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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For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the bug is already fixed, 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 change bug's subsystems, reply with:
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Re: [syzbot] [ntfs3?] KASAN: use-after-free Read in bcmp

[Pavel Skripkin]

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Hi Syzbot,

Syzbot <syzbot+53ce40c8c0322c06aea5@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

[-- Attachment #2: ph --]
[-- Type: text/plain, Size: 494 bytes --]

diff --git a/fs/ntfs3/super.c b/fs/ntfs3/super.c
index 1a02072b6b0e..e04e89b7335e 100644
--- a/fs/ntfs3/super.c
+++ b/fs/ntfs3/super.c
@@ -855,6 +855,11 @@ static int ntfs_init_from_boot(struct super_block *sb, u32 sector_size,
 
 check_boot:
 	err = -EINVAL;
+
+	/* Corrupted image; do not read OOB */
+	if (bh->b_size - sizeof(*boot) < boot_off)
+		goto out;
+
 	boot = (struct NTFS_BOOT *)Add2Ptr(bh->b_data, boot_off);
 
 	if (memcmp(boot->system_id, "NTFS    ", sizeof("NTFS    ") - 1)) {

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

[syzbot]

Hello,

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

Reported-and-tested-by: syzbot+53ce40c8c0322c06aea5@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.