Re: [Cluster-devel] [PATCH RESEND 2/8] fs: dlm: Fix the size of a buffer in dlm_create_debug_file()

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Oct 10, 2023 at 06:04:42PM -0400, Alexander Aring wrote:
> From: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> 
> 8 is not the maximum size of the suffix used when creating debugfs files.
> 
> Let the compiler compute the correct size, and only give a hint about the
> longest possible string that is used.
> 
> When building with W=1, this fixes the following warnings:
> 
>   fs/dlm/debug_fs.c: In function ‘dlm_create_debug_file’:
>   fs/dlm/debug_fs.c:1020:58: error: ‘snprintf’ output may be truncated before the last format character [-Werror=format-truncation=]
>    1020 |         snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_waiters", ls->ls_name);
>         |                                                          ^
>   fs/dlm/debug_fs.c:1020:9: note: ‘snprintf’ output between 9 and 73 bytes into a destination of size 72
>    1020 |         snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_waiters", ls->ls_name);
>         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>   fs/dlm/debug_fs.c:1031:50: error: ‘_queued_asts’ directive output may be truncated writing 12 bytes into a region of size between 8 and 72 [-Werror=format-truncation=]
>    1031 |         snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_queued_asts", ls->ls_name);
>         |                                                  ^~~~~~~~~~~~
>   fs/dlm/debug_fs.c:1031:9: note: ‘snprintf’ output between 13 and 77 bytes into a destination of size 72
>    1031 |         snprintf(name, DLM_LOCKSPACE_LEN + 8, "%s_queued_asts", ls->ls_name);
>         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> Fixes: 541adb0d4d10b ("fs: dlm: debugfs for queued callbacks")
> Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
> Signed-off-by: Alexander Aring <aahringo@redhat.com>
> ---
>  fs/dlm/debug_fs.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/dlm/debug_fs.c b/fs/dlm/debug_fs.c
> index e9726c6cbdf2..c93359ceaae6 100644
> --- a/fs/dlm/debug_fs.c
> +++ b/fs/dlm/debug_fs.c
> @@ -973,7 +973,8 @@ void dlm_delete_debug_comms_file(void *ctx)
>  
>  void dlm_create_debug_file(struct dlm_ls *ls)
>  {
> -	char name[DLM_LOCKSPACE_LEN + 8];
> +	/* Reserve enough space for the longest file name */
> +	char name[DLM_LOCKSPACE_LEN + sizeof("_queued_asts")];
>  
>  	/* format 1 */
>  
> -- 
> 2.39.3
> 

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>