linux-kernel - Re: [PATCH] jffs2: fix use of uninitialized variable

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Date: Mon, 1 Jul 2024 14:33:45 +0800
From: Zhihao Cheng <chengzhihao1@...wei.com>
To: Qingfang Deng <dqfext@...il.com>, David Woodhouse <dwmw2@...radead.org>,
	Richard Weinberger <richard@....at>, Qingfang Deng
	<qingfang.deng@...lower.com.cn>, <linux-mtd@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] jffs2: fix use of uninitialized variable

在 2024/7/1 12:52, Qingfang Deng 写道:
> From: Qingfang Deng <qingfang.deng@...lower.com.cn>
> 
> When building the kernel with -Wmaybe-uninitialized, the compiler
> reports this warning:
> 
> In function 'jffs2_mark_erased_block',
>      inlined from 'jffs2_erase_pending_blocks' at fs/jffs2/erase.c:116:4:
> fs/jffs2/erase.c:474:9: warning: 'bad_offset' may be used uninitialized [-Wmaybe-uninitialized]
>    474 |         jffs2_erase_failed(c, jeb, bad_offset);
>        |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> fs/jffs2/erase.c: In function 'jffs2_erase_pending_blocks':
> fs/jffs2/erase.c:402:18: note: 'bad_offset' was declared here
>    402 |         uint32_t bad_offset;
>        |                  ^~~~~~~~~~
> 
> When mtd->point() is used, jffs2_erase_pending_blocks can return -EIO
> without initializing bad_offset, which is later used at the filebad
> label in jffs2_mark_erased_block.
> Fix it by initializing this variable.
> 
> Fixes: 8a0f572397ca ("[JFFS2] Return values of jffs2_block_check_erase error paths")
> Signed-off-by: Qingfang Deng <qingfang.deng@...lower.com.cn>
> ---
>   fs/jffs2/erase.c | 7 +++----
>   1 file changed, 3 insertions(+), 4 deletions(-)
> 
Reviewed-by: Zhihao Cheng <chengzhihao1@...wei.com>
> diff --git a/fs/jffs2/erase.c b/fs/jffs2/erase.c
> index acd32f05b519..ef3a1e1b6cb0 100644
> --- a/fs/jffs2/erase.c
> +++ b/fs/jffs2/erase.c
> @@ -338,10 +338,9 @@ static int jffs2_block_check_erase(struct jffs2_sb_info *c, struct jffs2_erasebl
>   		} while(--retlen);
>   		mtd_unpoint(c->mtd, jeb->offset, c->sector_size);
>   		if (retlen) {
> -			pr_warn("Newly-erased block contained word 0x%lx at offset 0x%08tx\n",
> -				*wordebuf,
> -				jeb->offset +
> -				c->sector_size-retlen * sizeof(*wordebuf));
> +			*bad_offset = jeb->offset + c->sector_size - retlen * sizeof(*wordebuf);
> +			pr_warn("Newly-erased block contained word 0x%lx at offset 0x%08x\n",
> +				*wordebuf, *bad_offset);
>   			return -EIO;
>   		}
>   		return 0;
>