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authorVlastimil Babka <vbabka@suse.cz>2022-11-16 15:56:32 +0100
committerVlastimil Babka <vbabka@suse.cz>2022-11-27 23:35:04 +0100
commit346907ceb9d11b9e22677c142b45ff50dd20a66a (patch)
treea322488eba1e68b6ade9ea8e6e09a1deb784b99b /mm/slub.c
parentc18c20f16219516b12a4f2fd29c25e06be97e064 (diff)
mm, slab: ignore hardened usercopy parameters when disabled
With CONFIG_HARDENED_USERCOPY not enabled, there are no __check_heap_object() checks happening that would use the struct kmem_cache useroffset and usersize fields. Yet the fields are still initialized, preventing merging of otherwise compatible caches. Also the fields contribute to struct kmem_cache size unnecessarily when unused. Thus #ifdef them out completely when CONFIG_HARDENED_USERCOPY is disabled. In kmem_dump_obj() print object_size instead of usersize, as that's actually the intention. In a quick virtme boot test, this has reduced the number of caches in /proc/slabinfo from 131 to 111. Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: Christoph Lameter <cl@linux.com>
Diffstat (limited to 'mm/slub.c')
-rw-r--r--mm/slub.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/mm/slub.c b/mm/slub.c
index 157527d7101b..e32db8540767 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5502,11 +5502,13 @@ static ssize_t cache_dma_show(struct kmem_cache *s, char *buf)
SLAB_ATTR_RO(cache_dma);
#endif
+#ifdef CONFIG_HARDENED_USERCOPY
static ssize_t usersize_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(buf, "%u\n", s->usersize);
}
SLAB_ATTR_RO(usersize);
+#endif
static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
{
@@ -5803,7 +5805,9 @@ static struct attribute *slab_attrs[] = {
#ifdef CONFIG_FAILSLAB
&failslab_attr.attr,
#endif
+#ifdef CONFIG_HARDENED_USERCOPY
&usersize_attr.attr,
+#endif
#ifdef CONFIG_KFENCE
&skip_kfence_attr.attr,
#endif