linux-kernel - Re: [PATCH] ext4: Avoid a potential slab-out-of-bounds in ext4_group_desc

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Date:   Sat, 13 May 2023 00:59:31 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     jack@...e.cz, Tudor Ambarus <tudor.ambarus@...aro.org>
Cc:     "Theodore Ts'o" <tytso@....edu>, adilger.kernel@...ger.ca,
        cmm@...ibm.com, aneesh.kumar@...ux.vnet.ibm.com, mathur@...ibm.com,
        linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org,
        joneslee@...gle.com,
        syzbot+fc51227e7100c9294894@...kaller.appspotmail.com,
        stable@...r.kernel.org
Subject: Re: [PATCH] ext4: Avoid a potential slab-out-of-bounds in ext4_group_desc_csum


On Thu, 04 May 2023 12:15:25 +0000, Tudor Ambarus wrote:
> When modifying the block device while it is mounted by the filesystem,
> syzbot reported the following:
> 
> BUG: KASAN: slab-out-of-bounds in crc16+0x206/0x280 lib/crc16.c:58
> Read of size 1 at addr ffff888075f5c0a8 by task syz-executor.2/15586
> 
> CPU: 1 PID: 15586 Comm: syz-executor.2 Not tainted 6.2.0-rc5-syzkaller-00205-gc96618275234 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0x1b1/0x290 lib/dump_stack.c:106
>  print_address_description+0x74/0x340 mm/kasan/report.c:306
>  print_report+0x107/0x1f0 mm/kasan/report.c:417
>  kasan_report+0xcd/0x100 mm/kasan/report.c:517
>  crc16+0x206/0x280 lib/crc16.c:58
>  ext4_group_desc_csum+0x81b/0xb20 fs/ext4/super.c:3187
>  ext4_group_desc_csum_set+0x195/0x230 fs/ext4/super.c:3210
>  ext4_mb_clear_bb fs/ext4/mballoc.c:6027 [inline]
>  ext4_free_blocks+0x191a/0x2810 fs/ext4/mballoc.c:6173
>  ext4_remove_blocks fs/ext4/extents.c:2527 [inline]
>  ext4_ext_rm_leaf fs/ext4/extents.c:2710 [inline]
>  ext4_ext_remove_space+0x24ef/0x46a0 fs/ext4/extents.c:2958
>  ext4_ext_truncate+0x177/0x220 fs/ext4/extents.c:4416
>  ext4_truncate+0xa6a/0xea0 fs/ext4/inode.c:4342
>  ext4_setattr+0x10c8/0x1930 fs/ext4/inode.c:5622
>  notify_change+0xe50/0x1100 fs/attr.c:482
>  do_truncate+0x200/0x2f0 fs/open.c:65
>  handle_truncate fs/namei.c:3216 [inline]
>  do_open fs/namei.c:3561 [inline]
>  path_openat+0x272b/0x2dd0 fs/namei.c:3714
>  do_filp_open+0x264/0x4f0 fs/namei.c:3741
>  do_sys_openat2+0x124/0x4e0 fs/open.c:1310
>  do_sys_open fs/open.c:1326 [inline]
>  __do_sys_creat fs/open.c:1402 [inline]
>  __se_sys_creat fs/open.c:1396 [inline]
>  __x64_sys_creat+0x11f/0x160 fs/open.c:1396
>  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: 0033:0x7f72f8a8c0c9
> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 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:00007f72f97e3168 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
> RAX: ffffffffffffffda RBX: 00007f72f8bac050 RCX: 00007f72f8a8c0c9
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000280
> RBP: 00007f72f8ae7ae9 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: 00007ffd165348bf R14: 00007f72f97e3300 R15: 0000000000022000
> 
> [...]

Applied, thanks!

[1/1] ext4: Avoid a potential slab-out-of-bounds in ext4_group_desc_csum
      commit: 707548336a9a5b1745074265c4d4d2cf2b4b0f43

Best regards,
-- 
Theodore Ts'o <tytso@....edu>