From: "Mickaël Salaün" <mic@digikod.net>
To: Kees Cook <keescook@chromium.org>
Cc: James Morris <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH] landlock: Drop "const" argument qualifier to avoid GCC 4.9 warnings
Date: Mon, 13 Sep 2021 13:19:19 +0200 [thread overview]
Message-ID: <b269cdc1-a4f0-d614-f026-dc0f7c455da0@digikod.net> (raw)
In-Reply-To: <20210910223613.3225685-1-keescook@chromium.org>
On 11/09/2021 00:36, Kees Cook wrote:
> When building under GCC 4.9, the compiler warns about const mismatches:
>
> security/landlock/ruleset.c: In function 'insert_rule':
> security/landlock/ruleset.c:196:34: error: passing argument 2 of 'create_rule' from incompatible pointer type [-Werror]
> new_rule = create_rule(object, &this->layers, this->num_layers,
> ^
> security/landlock/ruleset.c:69:30: note: expected 'const struct landlock_layer ** const' but argument is of type 'struct landlock_layer (*)[]'
> static struct landlock_rule *create_rule(
> ^
> security/landlock/ruleset.c: In function 'landlock_insert_rule':
> security/landlock/ruleset.c:240:38: error: passing argument 3 of 'insert_rule' from incompatible pointer type [-Werror]
> return insert_rule(ruleset, object, &layers, ARRAY_SIZE(layers));
> ^
> security/landlock/ruleset.c:144:12: note: expected 'const struct landlock_layer ** const' but argument is of type 'struct landlock_layer (*)[1]'
> static int insert_rule(struct landlock_ruleset *const ruleset,
I guess this is a bug in GCC 4.9 (i.e. missing automatic const upgrade).
Couldn't we backport a fix to GCC 4.9 instead?
> ^
>
> Drop "const" from the function definition.
>
> Cc: "Mickaël Salaün" <mic@digikod.net>
> Cc: James Morris <jmorris@namei.org>
> Cc: "Serge E. Hallyn" <serge@hallyn.com>
> Cc: linux-security-module@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
> security/landlock/ruleset.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/security/landlock/ruleset.c b/security/landlock/ruleset.c
> index ec72b9262bf3..64c37af88ee7 100644
> --- a/security/landlock/ruleset.c
> +++ b/security/landlock/ruleset.c
> @@ -68,7 +68,7 @@ static void build_check_rule(void)
>
> static struct landlock_rule *create_rule(
> struct landlock_object *const object,
> - const struct landlock_layer (*const layers)[],
> + struct landlock_layer (*layers)[],
The "const layers" is not an issue, it should not be removed.
> const u32 num_layers,
> const struct landlock_layer *const new_layer)
> {
> @@ -143,7 +143,7 @@ static void build_check_ruleset(void)
> */
> static int insert_rule(struct landlock_ruleset *const ruleset,
> struct landlock_object *const object,
> - const struct landlock_layer (*const layers)[],
> + struct landlock_layer (*layers)[],
Same here for the second const.
> size_t num_layers)
> {
> struct rb_node **walker_node;
>
next prev parent reply other threads:[~2021-09-13 11:27 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-10 22:36 [PATCH] landlock: Drop "const" argument qualifier to avoid GCC 4.9 warnings Kees Cook
2021-09-13 11:19 ` Mickaël Salaün [this message]
2021-09-13 16:16 ` Kees Cook
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