linux-kernel - Re: [PATCH] fs: exfat: Fix corrupted error code handling in exfat_find_empty

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Message-ID: <5fa3c9d2-e77b-4cf9-95d2-f1fc0eb7292e@samsung.com>
Date: Thu, 4 Dec 2025 20:58:34 +0900
From: Sungjong Seo <sj1557.seo@...sung.com>
To: Haotian Zhang <vulab@...as.ac.cn>, linkinjeon@...nel.org,
	yuezhang.mo@...y.com
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fs: exfat: Fix corrupted error code handling in
 exfat_find_empty_entry()

Hi, Haotian,

On 25. 12. 3. 16:08, Haotian Zhang wrote:
> exfat_find_empty_entry() stores the return value of
> exfat_alloc_cluster() in an unsigned int. When
> exfat_alloc_cluster() returns a negative errno, it is
> converted to a large positive value, which corrupts
> error propagation to the caller.
Have you ever encountered an actual error?
IMO, due to implicit type conversion, it should work as follows,
so, I don't think there will be any real issues.

int -> unsigned int -> int

Anyway, it makes sense to modify the type of ret from unsigned int to int.
What about changing the title and comment?

Thanks.
SJ

> 
> Change the type of ret to int so that negative errno
> values are preserved.
> 
> Fixes: 5f2aa075070c ("exfat: add inode operations")
> Signed-off-by: Haotian Zhang <vulab@...as.ac.cn>
> ---
>  fs/exfat/namei.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
> index f5f1c4e8a29f..f2a87ecd79f9 100644
> --- a/fs/exfat/namei.c
> +++ b/fs/exfat/namei.c
> @@ -304,8 +304,8 @@ static int exfat_find_empty_entry(struct inode *inode,
>  		struct exfat_chain *p_dir, int num_entries,
>  		struct exfat_entry_set_cache *es)
>  {
> -	int dentry;
> -	unsigned int ret, last_clu;
> +	int dentry, ret;
> +	unsigned int last_clu;
>  	loff_t size = 0;
>  	struct exfat_chain clu;
>  	struct super_block *sb = inode->i_sb;