| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20251121101155.173d63bd6611cd3c4aa22cf9@linux-foundation.org>
Date: Fri, 21 Nov 2025 10:11:55 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: syzbot <syzbot+b0a0670332b6b3230a0a@...kaller.appspotmail.com>
Cc: linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
syzkaller-bugs@...glegroups.com, willy@...radead.org
Subject: Re: [syzbot] [ext4?] WARNING in __folio_mark_dirty (3)
On Thu, 20 Nov 2025 08:41:31 -0800 syzbot <syzbot+b0a0670332b6b3230a0a@...kaller.appspotmail.com> wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 23cb64fb7625 Merge tag 'soc-fixes-6.18-3' of git://git.ker..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1287997c580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=38a0c4cddc846161
> dashboard link: https://syzkaller.appspot.com/bug?extid=b0a0670332b6b3230a0a
> compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=172cd658580000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15378484580000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/a14ebce6c664/disk-23cb64fb.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/7703c3032e2f/vmlinux-23cb64fb.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/a16c5b94924d/bzImage-23cb64fb.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/4fa9525269b6/mount_0.gz
> fsck result: failed (log: https://syzkaller.appspot.com/x/fsck.log?x=11d42a12580000)
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b0a0670332b6b3230a0a@...kaller.appspotmail.com
Thanks.
: void __folio_mark_dirty(struct folio *folio, struct address_space *mapping,
: int warn)
: {
: unsigned long flags;
:
: /*
: * Shmem writeback relies on swap, and swap writeback is LRU based,
: * not using the dirty mark.
: */
: VM_WARN_ON_ONCE(folio_test_swapcache(folio) || shmem_mapping(mapping));
:
: xa_lock_irqsave(&mapping->i_pages, flags);
: if (folio->mapping) { /* Race with truncate? */
: WARN_ON_ONCE(warn && !folio_test_uptodate(folio));
this
: folio_account_dirtied(folio, mapping);
: __xa_set_mark(&mapping->i_pages, folio->index,
: PAGECACHE_TAG_DIRTY);
: }
: xa_unlock_irqrestore(&mapping->i_pages, flags);
: }
I'm guessing that ext4 permitted a non-uptodate folio to find its way
into the blockdev mapping then the pagefault code tried to modify it
and got upset.
> EXT4-fs error (device loop0): ext4_ext_remove_space:2955: inode #15: comm syz.0.51: pblk 0 bad header/extent: invalid extent entries - magic f30a, entries 2, max 4(4), depth 0(0)
> EXT4-fs error (device loop0) in ext4_setattr:6050: Corrupt filesystem
> EXT4-fs error (device loop0): ext4_validate_block_bitmap:441: comm syz.0.51: bg 0: block 112: padding at end of block bitmap is not set
> EXT4-fs error (device loop0): ext4_map_blocks:778: inode #15: block 3: comm syz.0.51: lblock 3 mapped to illegal pblock 3 (length 1)
> EXT4-fs error (device loop0): ext4_ext_remove_space:2955: inode #15: comm syz.0.51: pblk 0 bad header/extent: invalid extent entries - magic f30a, entries 2, max 4(4), depth 0(0)
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 6107 at mm/page-writeback.c:2716 __folio_mark_dirty+0x1fb/0xe20 mm/page-writeback.c:2716
> Modules linked in:
> CPU: 0 UID: 0 PID: 6107 Comm: syz.0.51 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
> RIP: 0010:__folio_mark_dirty+0x1fb/0xe20 mm/page-writeback.c:2716
> Code: 3c 38 00 74 08 48 89 df e8 52 a7 26 00 4c 8b 33 4c 89 f6 48 83 e6 08 31 ff e8 d1 ed c4 ff 49 83 e6 08 75 1c e8 66 e8 c4 ff 90 <0f> 0b 90 eb 16 e8 5b e8 c4 ff e9 7e 07 00 00 e8 51 e8 c4 ff eb 05
> RSP: 0018:ffffc90003a079d0 EFLAGS: 00010293
> RAX: ffffffff81f9c4ea RBX: ffffea0001213400 RCX: ffff888025260000
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
> RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000
> R10: dffffc0000000000 R11: fffff94000242681 R12: ffff8880416cb4f0
> R13: ffff8880416cb4e8 R14: 0000000000000000 R15: dffffc0000000000
> FS: 0000555587ebe500(0000) GS:ffff888126df7000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000200000000440 CR3: 000000002e288000 CR4: 00000000003526f0
> Call Trace:
> <TASK>
> block_dirty_folio+0x17a/0x1d0 fs/buffer.c:754
> fault_dirty_shared_page+0x103/0x570 mm/memory.c:3519
> wp_page_shared mm/memory.c:3906 [inline]
> do_wp_page+0x263e/0x4930 mm/memory.c:4109
> handle_pte_fault mm/memory.c:6211 [inline]
> __handle_mm_fault mm/memory.c:6336 [inline]
> handle_mm_fault+0x97c/0x3400 mm/memory.c:6505
> do_user_addr_fault+0xa7c/0x1380 arch/x86/mm/fault.c:1336
> handle_page_fault arch/x86/mm/fault.c:1476 [inline]
> exc_page_fault+0x82/0x100 arch/x86/mm/fault.c:1532
> asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
> RIP: 0033:0x7f385fe87398
> Code: fc 89 37 c3 c5 fa 6f 06 c5 fa 6f 4c 16 f0 c5 fa 7f 07 c5 fa 7f 4c 17 f0 c3 66 0f 1f 84 00 00 00 00 00 48 8b 4c 16 f8 48 8b 36 <48> 89 37 48 89 4c 17 f8 c3 c5 fe 6f 54 16 e0 c5 fe 6f 5c 16 c0 c5
> RSP: 002b:00007ffd3b8738f8 EFLAGS: 00010246
> RAX: 0000200000000440 RBX: 0000000000000004 RCX: 0030656c69662f2e
> RDX: 0000000000000008 RSI: 0030656c69662f2e RDI: 0000200000000440
> RBP: 0000000000000000 R08: 0000001b2d820000 R09: 0000000000000001
> R10: 0000000000000001 R11: 0000000000000009 R12: 00007f3860115fac
> R13: 00007f3860115fa0 R14: fffffffffffffffe R15: 0000000000000004
> </TASK>
Powered by blists - more mailing lists