Date: Fri, 2 Feb 2024 00:17:19 +0800
From: Gao Xiang <hsiangkao@...ux.alibaba.com>
To: syzbot <syzbot+88ad8b0517a9d3bb9dc8@...kaller.appspotmail.com>,
 chao@...nel.org, huyue2@...lpad.com, jefflexu@...ux.alibaba.com,
 linux-erofs@...ts.ozlabs.org, linux-fsdevel@...r.kernel.org,
 linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com,
 xiang@...nel.org
Subject: Re: [syzbot] [erofs?] KMSAN: uninit-value in z_erofs_lz4_decompress
 (3)

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

On 2024/2/1 19:04, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    9f8413c4a66f Merge tag 'cgroup-for-6.8' of git://git.kerne..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=13d26b1fe80000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=656820e61b758b15
> dashboard link: https://syzkaller.appspot.com/bug?extid=88ad8b0517a9d3bb9dc8
> 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=11377218180000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=111fd038180000
> 
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/79d9f2f4b065/disk-9f8413c4.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/cbc68430d9c6/vmlinux-9f8413c4.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/9740ad9fc172/bzImage-9f8413c4.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/2f79f30d7608/mount_0.gz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+88ad8b0517a9d3bb9dc8@...kaller.appspotmail.com
> 
> erofs: (device loop0): z_erofs_lz4_decompress_mem: failed to decompress -42 in[46, 0] out[9000]
> =====================================================
> BUG: KMSAN: uninit-value in hex_dump_to_buffer+0xae9/0x10f0 lib/hexdump.c:194
>   hex_dump_to_buffer+0xae9/0x10f0 lib/hexdump.c:194
>   print_hex_dump+0x13d/0x3e0 lib/hexdump.c:276
>   z_erofs_lz4_decompress_mem fs/erofs/decompressor.c:252 [inline]
>   z_erofs_lz4_decompress+0x257e/0x2a70 fs/erofs/decompressor.c:311
>   z_erofs_decompress_pcluster fs/erofs/zdata.c:1290 [inline]
>   z_erofs_decompress_queue+0x338c/0x6460 fs/erofs/zdata.c:1372
>   z_erofs_decompressqueue_work+0x57/0x70 fs/erofs/zdata.c:1387
>   process_one_work kernel/workqueue.c:2633 [inline]
>   process_scheduled_works+0x104e/0x1e70 kernel/workqueue.c:2706
>   worker_thread+0xf45/0x1490 kernel/workqueue.c:2787
>   kthread+0x3ed/0x540 kernel/kthread.c:388
>   ret_from_fork+0x66/0x80 arch/x86/kernel/process.c:147
>   ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
> 
> Uninit was created at:
>   __alloc_pages+0x9a4/0xe00 mm/page_alloc.c:4591
>   alloc_pages_mpol+0x62b/0x9d0 mm/mempolicy.c:2133
>   alloc_pages mm/mempolicy.c:2204 [inline]
>   folio_alloc+0x1da/0x380 mm/mempolicy.c:2211
>   filemap_alloc_folio+0xa5/0x430 mm/filemap.c:974
>   page_cache_ra_unbounded+0x2cc/0x960 mm/readahead.c:247
>   do_page_cache_ra mm/readahead.c:299 [inline]
>   page_cache_ra_order+0xfeb/0x10a0 mm/readahead.c:546
>   ondemand_readahead+0x132b/0x1710 mm/readahead.c:668
>   page_cache_sync_ra+0x724/0x760 mm/readahead.c:695
>   page_cache_sync_readahead include/linux/pagemap.h:1283 [inline]
>   filemap_get_pages+0x4c7/0x2c90 mm/filemap.c:2497
>   filemap_read+0x59e/0x14d0 mm/filemap.c:2593
>   generic_file_read_iter+0x136/0xad0 mm/filemap.c:2781
>   __kernel_read+0x3bb/0x9e0 fs/read_write.c:434
>   integrity_kernel_read+0x77/0x90 security/integrity/iint.c:221
>   ima_calc_file_hash_tfm security/integrity/ima/ima_crypto.c:485 [inline]
>   ima_calc_file_shash security/integrity/ima/ima_crypto.c:516 [inline]
>   ima_calc_file_hash+0x1743/0x3cc0 security/integrity/ima/ima_crypto.c:573
>   ima_collect_measurement+0x44d/0xdd0 security/integrity/ima/ima_api.c:290
>   process_measurement+0x2936/0x3ef0 security/integrity/ima/ima_main.c:359
>   ima_file_check+0xb3/0x100 security/integrity/ima/ima_main.c:557
>   do_open fs/namei.c:3624 [inline]
>   path_openat+0x4d05/0x5ac0 fs/namei.c:3779
>   do_filp_open+0x20d/0x590 fs/namei.c:3806
>   do_sys_openat2+0x1bf/0x2f0 fs/open.c:1404
>   do_sys_open fs/open.c:1419 [inline]
>   __do_sys_open fs/open.c:1427 [inline]
>   __se_sys_open fs/open.c:1423 [inline]
>   __x64_sys_open+0x275/0x2d0 fs/open.c:1423
>   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>   do_syscall_64+0x6d/0x140 arch/x86/entry/common.c:83
>   entry_SYSCALL_64_after_hwframe+0x63/0x6b
> 
> CPU: 0 PID: 4393 Comm: kworker/u5:1 Not tainted 6.7.0-syzkaller-00562-g9f8413c4a66f #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
> Workqueue: erofs_worker z_erofs_decompressqueue_work
> =====================================================
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@...glegroups.com.
> 
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> 
> If the report is already addressed, 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 overwrite report's subsystems, reply with:
> #syz set subsystems: new-subsystem
> (See the list of subsystem names on the web dashboard)
> 
> If the report is a duplicate of another one, reply with:
> #syz dup: exact-subject-of-another-report
> 
> If you want to undo deduplication, reply with:
> #syz undup

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