linux-kernel - KMSAN: uninit-value in nilfs_add_checksums_on

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Date:   Wed, 15 Feb 2023 18:43:46 -0800
From:   Dipanjan Das <mail.dipanjan.das@...il.com>
To:     konishi.ryusuke@...il.com, linux-nilfs@...r.kernel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:     syzkaller <syzkaller@...glegroups.com>,
        Marius Fleischer <fleischermarius@...glemail.com>,
        Priyanka Bose <its.priyanka.bose@...il.com>
Subject: KMSAN: uninit-value in nilfs_add_checksums_on_logs

Hi,

We would like to report the following bug which has been found by our
modified version of syzkaller.

======================================================
description: KMSAN: uninit-value in nilfs_add_checksums_on_logs
affected file: fs/nilfs2/segbuf.c
kernel version: 6.2.0-rc5
kernel commit: 41c66f47061608dc1fd493eebce198f0e74cc2d7
git tree: kmsan
kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=a9a22da1efde3af6
crash reproducer: attached
======================================================
Crash log:
======================================================
NILFS (loop4): segctord starting. Construction interval = 5 seconds,
CP frequency < 30 seconds
=====================================================
BUG: KMSAN: uninit-value in crc32_body lib/crc32.c:112 [inline]
BUG: KMSAN: uninit-value in crc32_le_generic lib/crc32.c:179 [inline]
BUG: KMSAN: uninit-value in crc32_le_base+0x3b7/0xc30 lib/crc32.c:197
 crc32_body lib/crc32.c:112 [inline]
 crc32_le_generic lib/crc32.c:179 [inline]
 crc32_le_base+0x3b7/0xc30 lib/crc32.c:197
 nilfs_segbuf_fill_in_data_crc fs/nilfs2/segbuf.c:208 [inline]
 nilfs_add_checksums_on_logs+0x6ec/0xea0 fs/nilfs2/segbuf.c:321
 nilfs_segctor_do_construct+0xa636/0xe870 fs/nilfs2/segment.c:2076
 nilfs_segctor_construct+0x222/0xe10 fs/nilfs2/segment.c:2379
 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2487 [inline]
 nilfs_segctor_thread+0xc19/0x11c0 fs/nilfs2/segment.c:2570
 kthread+0x30b/0x420 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

Uninit was created at:
 __alloc_pages+0x767/0xee0 mm/page_alloc.c:5572
 alloc_pages+0xa9a/0xd90 mm/mempolicy.c:2286
 folio_alloc+0x41/0x100 mm/mempolicy.c:2296
 filemap_alloc_folio+0xa5/0x450 mm/filemap.c:972
 __filemap_get_folio+0xe7c/0x1960 mm/filemap.c:1966
 pagecache_get_page+0x46/0x270 mm/folio-compat.c:98
 find_or_create_page include/linux/pagemap.h:612 [inline]
 grow_dev_page fs/buffer.c:946 [inline]
 grow_buffers fs/buffer.c:1011 [inline]
 __getblk_slow fs/buffer.c:1038 [inline]
 __getblk_gfp+0x365/0x1750 fs/buffer.c:1333
 sb_getblk include/linux/buffer_head.h:356 [inline]
 nilfs_segbuf_extend_segsum fs/nilfs2/segbuf.c:99 [inline]
 nilfs_segbuf_reset+0xfd/0x520 fs/nilfs2/segbuf.c:129
 nilfs_segctor_reset_segment_buffer fs/nilfs2/segment.c:421 [inline]
 nilfs_segctor_collect fs/nilfs2/segment.c:1499 [inline]
 nilfs_segctor_do_construct+0x20c6/0xe870 fs/nilfs2/segment.c:2045
 nilfs_segctor_construct+0x222/0xe10 fs/nilfs2/segment.c:2379
 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2487 [inline]
 nilfs_segctor_thread+0xc19/0x11c0 fs/nilfs2/segment.c:2570
 kthread+0x30b/0x420 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

CPU: 1 PID: 11600 Comm: segctord Not tainted 6.2.0-rc5-00010-g41c66f470616 #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
=====================================================

-- 
Thanks and Regards,

Dipanjan

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