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Date: Thu, 28 Dec 2023 09:29:55 +0800
From: Yue Hu <zbestahu@gmail.com>
To: Gao Xiang <hsiangkao@linux.alibaba.com>
Cc: linux-erofs@lists.ozlabs.org,
 syzbot+6c746eea496f34b3161d@syzkaller.appspotmail.com, LKML
 <linux-kernel@vger.kernel.org>, huyue2@coolpad.com
Subject: Re: [PATCH] erofs: avoid debugging output for (de)compressed data
Message-ID: <20231228092955.00000520.zbestahu@gmail.com>
In-Reply-To: <20231227151903.2900413-1-hsiangkao@linux.alibaba.com>
References: <000000000000321c24060d7cfa1c@google.com>
	<20231227151903.2900413-1-hsiangkao@linux.alibaba.com>
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On Wed, 27 Dec 2023 23:19:03 +0800
Gao Xiang <hsiangkao@linux.alibaba.com> wrote:

> Syzbot reported a KMSAN warning,
> erofs: (device loop0): z_erofs_lz4_decompress_mem: failed to decompress -12 in[46, 4050] out[917]
> =====================================================
> BUG: KMSAN: uninit-value in 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_runqueue+0x36cd/0x3830
>   z_erofs_read_folio+0x435/0x810 fs/erofs/zdata.c:1843
> 
> The root cause is that the printed decompressed buffer may be filled
> incompletely due to decompression failure.  Since they were once only
> used for debugging, get rid of them now.
> 
> Reported-by: syzbot+6c746eea496f34b3161d@syzkaller.appspotmail.com
> Closes: https://lore.kernel.org/r/000000000000321c24060d7cfa1c@google.com
> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Reviewed-by: Yue Hu <huyue2@coolpad.com>