Re: [dm-devel] [PATCH] md: dm-ioctl: drop always-false condition

Mikulas Patocka
2023-01-18T12:37:13Z

On Tue, 17 Jan 2023, Sergey Shtylyov wrote:

> The expression 'indata[3] > ULONG_MAX' always evaluates to false since
> indata[] is declared as an array of *unsigned long* elements and #define
> ULONG_MAX represents the max value of that exact type...
>
> Note that gcc seems to be able to detect the dead code here and eliminate
> this check anyway...
>
> Found by Linux Verification Center (linuxtesting.org) with the SVACE static
> analysis tool.
>
> Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>

Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>

> ---
> This patch is atop of the 'for-next' branch of the device-mapper repo...
>
> drivers/md/dm-ioctl.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> Index: linux-dm/drivers/md/dm-ioctl.c
> ===================================================================
> --- linux-dm.orig/drivers/md/dm-ioctl.c
> +++ linux-dm/drivers/md/dm-ioctl.c
> @@ -1073,8 +1073,7 @@ static int dev_set_geometry(struct file
> goto out;
> }
>
> - if (indata[0] > 65535 || indata[1] > 255 ||
> - indata[2] > 255 || indata[3] > ULONG_MAX) {
> + if (indata[0] > 65535 || indata[1] > 255 || indata[2] > 255) {
> DMERR("Geometry exceeds range limits.");
> goto out;
> }
>
> --
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