linux-kernel - Re: [PATCH] sysv: use BUILD_BUG

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Message-ID: <dc7771f0-e4db-ee5c-a66d-b5db5f26a59d@gmail.com>
Date:   Wed, 1 Sep 2021 13:15:29 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     dhowells@...hat.com, viro@...iv.linux.org.uk
Cc:     linux-kernel@...r.kernel.org, hch@...radead.org
Subject: Re: [PATCH] sysv: use BUILD_BUG_ON instead of runtime check

On 8/13/21 15:30, Pavel Skripkin wrote:
> There was runtime checks about sizes of struct v7_super_block
> and struct sysv_inode. If one of these checks fail kernel will panic.
> Since these values are known on complite time let's use BUILD_BUG_ON(),
> because it's standard mechanism for validation checking at build time
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
> ---
>   fs/sysv/super.c | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/sysv/super.c b/fs/sysv/super.c
> index cc8e2ed155c8..d1def0771a40 100644
> --- a/fs/sysv/super.c
> +++ b/fs/sysv/super.c
> @@ -474,10 +474,8 @@ static int v7_fill_super(struct super_block *sb, void *data, int silent)
>   	struct sysv_sb_info *sbi;
>   	struct buffer_head *bh;
>   
> -	if (440 != sizeof (struct v7_super_block))
> -		panic("V7 FS: bad super-block size");
> -	if (64 != sizeof (struct sysv_inode))
> -		panic("sysv fs: bad i-node size");
> +	BUILD_BUG_ON(sizeof(struct v7_super_block) != 440);
> +	BUILD_BUG_ON(sizeof(struct sysv_inode) != 64);
>   
>   	sbi = kzalloc(sizeof(struct sysv_sb_info), GFP_KERNEL);
>   	if (!sbi)
> 

Hi, David and Alexander!


Maybe, this one can go through one of your trees? I didn't find any sysv 
related trees, so..

Lore link to the patch: 
https://lore.kernel.org/lkml/20210813123020.22971-1-paskripkin@gmail.com/



Thank you!


With regards,
Pavel Skripkin