Re: [PATCH 2/2] lockd: change the proc_handler for nsm_use_hostnames

Kees Cook
2021-09-16T22:05:25Z

On Tue, Aug 03, 2021 at 12:59:37PM +0200, Thomas Huth wrote:
> From: Jia He <hejianet@gmail.com>
>
> nsm_use_hostnames is a module parameter and it will be exported to sysctl
> procfs. This is to let user sometimes change it from userspace. But the
> minimal unit for sysctl procfs read/write it sizeof(int).
> In big endian system, the converting from/to bool to/from int will cause
> error for proc items.
>
> This patch use a new proc_handler proc_dobool to fix it.
>
> Signed-off-by: Jia He <hejianet@gmail.com>
> Reviewed-by: Pan Xinhui <xinhui.pan@linux.vnet.ibm.com>
> [thuth: Fix typo in commit message]
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
> fs/lockd/svc.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/lockd/svc.c b/fs/lockd/svc.c
> index 2de048f80eb8..0ab9756ed235 100644
> --- a/fs/lockd/svc.c
> +++ b/fs/lockd/svc.c
> @@ -584,7 +584,7 @@ static struct ctl_table nlm_sysctls[] = {
> .data = &nsm_use_hostnames,
> .maxlen = sizeof(int),

For robustness, maybe this should be:

.maxlen = sizeof(nsm_use_hostnames),

> .mode = 0644,
> - .proc_handler = proc_dointvec,
> + .proc_handler = proc_dobool,
> },
> {
> .procname = "nsm_local_state",
> --
> 2.27.0
>

Reviewed-by: Kees Cook <keescook@chromium.org>

Also, I wonder what other BE-corrupted bools are out there?

--
Kees Cook