Re: [PATCH] landlock: Drop "const" argument qualifier to avoid GCC 4.9 warnings
From: Mickaël Salaün <mic@digikod.net>
Date: 2021-09-13 11:27:07
Also in:
linux-hardening, lkml
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?
quoted hunk ↗ jump to hunk
^ 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 <redacted> --- 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.
quoted hunk ↗ jump to hunk
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;