linux-kernel - Re: [PATCH] squashfs: Avoid mem leak in squashfs_fill

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Message-ID: <2156fc8a-a43b-4986-8537-d1d530821dbf@squashfs.org.uk>
Date: Mon, 11 Aug 2025 23:35:26 +0100
From: Phillip Lougher <phillip@...ashfs.org.uk>
To: scott_gzh@....com
Cc: linux-kernel@...r.kernel.org, Scott GUO <scottzhguo@...cent.com>
Subject: Re: [PATCH] squashfs: Avoid mem leak in squashfs_fill_super



On 11/08/2025 07:19, scott_gzh@....com wrote:
> From: Scott GUO <scottzhguo@...cent.com>
> 
> If sb_min_blocksize returns 0, -EINVAL was returned without freeing
> sb->s_fs_info, causing mem leak.
> 
> Fix it by goto failed_mount.
> 

Thanks for spotting this, but, NACK to the patch.

A better fix is to call sb_min_blocksize and check the
return result before the memory is allocated.

Phillip

> Fixes: 734aa85390ea ("Squashfs: check return result of sb_min_blocksize")
> Signed-off-by: Scott GUO <scottzhguo@...cent.com>
> ---
>   fs/squashfs/super.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
> index 992ea0e37257..7d501083b2e3 100644
> --- a/fs/squashfs/super.c
> +++ b/fs/squashfs/super.c
> @@ -201,10 +201,12 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
>   
>   	msblk->panic_on_errors = (opts->errors == Opt_errors_panic);
>   
> +	err = -EINVAL;
> +
>   	msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);
>   	if (!msblk->devblksize) {
>   		errorf(fc, "squashfs: unable to set blocksize\n");
> -		return -EINVAL;
> +		goto failed_mount;
>   	}
>   
>   	msblk->devblksize_log2 = ffz(~msblk->devblksize);
> @@ -227,8 +229,6 @@ static int squashfs_fill_super(struct super_block *sb, struct fs_context *fc)
>   		goto failed_mount;
>   	}
>   
> -	err = -EINVAL;
> -
>   	/* Check it is a SQUASHFS superblock */
>   	sb->s_magic = le32_to_cpu(sblk->s_magic);
>   	if (sb->s_magic != SQUASHFS_MAGIC) {