[PATCH v2] keys: prevent slab cache merging for key_jar

[Jarkko Sakkinen]

On Wed, Jun 10, 2026 at 07:50:52AM +0100, Mohammed EL Kadiri wrote:
> Add SLAB_NO_MERGE to key_jar to prevent the allocator from merging it
> with other similarly-sized caches. This hardens struct key isolation by
> ensuring dedicated slab pages.
> 
> Acked-by: Vlastimil Babka (SUSE) <vbabka at kernel.org>
> Signed-off-by: Mohammed EL Kadiri <med08elkadiri at gmail.com>
> ---
>  security/keys/key.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/security/keys/key.c b/security/keys/key.c
> index 3bbdde778631..592b65cf8539 100644
> --- a/security/keys/key.c
> +++ b/security/keys/key.c
> @@ -1275,7 +1275,7 @@ void __init key_init(void)
>  {
>  	/* allocate a slab in which we can store keys */
>  	key_jar = kmem_cache_create("key_jar", sizeof(struct key),
> -			0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
> +			0, SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_NO_MERGE, NULL);
>  
>  	/* add the special key types */
>  	list_add_tail(&key_type_keyring.link, &key_types_list);
> -- 
> 2.43.0
> 

I swapped the commit.

https://git.kernel.org/pub/scm/linux/kernel/git/jarkko/linux-tpmdd.git/log/?h=for-next-keys

BR, Jarkko