SLUB: Fix merged slab cache names
As explained by Linus "I'm Proud to be an American" Torvalds:
Looking at the merging code, I actually think it's totally
buggy. If you have something like this:
- load module A: create slab cache A
- load module B: create slab cache B that can merge with A
- unload module A
- "cat /proc/slabinfo": BOOM. Oops.
exactly because the name is not handled correctly, and you'll have
module B holding open a slab cache that has a name pointer that points
to module A that no longer exists.
This patch fixes the problem by using kstrdup() to allocate dynamic memory for
->name of "struct kmem_cache" as suggested by Christoph Lameter.
Acked-by: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Conflicts:
mm/slub.c
diff --git a/mm/slub.c b/mm/slub.c
index 05674aa..42ce173 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -209,6 +209,7 @@
{ return 0; }
static inline void sysfs_slab_remove(struct kmem_cache *s)
{
+ kfree(s->name);
kfree(s);
}
@@ -3169,6 +3170,16 @@
slab_state = UP;
/* Provide the correct kmalloc names now that the caches are up */
+ if (KMALLOC_MIN_SIZE <= 32) {
+ kmalloc_caches[1]->name = kstrdup(kmalloc_caches[1]->name, GFP_NOWAIT);
+ BUG_ON(!kmalloc_caches[1]->name);
+ }
+
+ if (KMALLOC_MIN_SIZE <= 64) {
+ kmalloc_caches[2]->name = kstrdup(kmalloc_caches[2]->name, GFP_NOWAIT);
+ BUG_ON(!kmalloc_caches[2]->name);
+ }
+
for (i = KMALLOC_SHIFT_LOW; i < SLUB_PAGE_SHIFT; i++) {
char *s = kasprintf(GFP_NOWAIT, "kmalloc-%d", 1 << i);
@@ -3271,6 +3282,7 @@
size_t align, unsigned long flags, void (*ctor)(void *))
{
struct kmem_cache *s;
+ char *n;
if (WARN_ON(!name))
return NULL;
@@ -3294,19 +3306,25 @@
return s;
}
+ n = kstrdup(name, GFP_KERNEL);
+ if (!n)
+ goto err;
+
s = kmalloc(kmem_size, GFP_KERNEL);
if (s) {
- if (kmem_cache_open(s, name,
+ if (kmem_cache_open(s, n,
size, align, flags, ctor)) {
list_add(&s->list, &slab_caches);
if (sysfs_slab_add(s)) {
list_del(&s->list);
+ kfree(n);
kfree(s);
goto err;
}
up_write(&slub_lock);
return s;
}
+ kfree(n);
kfree(s);
}
up_write(&slub_lock);
@@ -4439,6 +4457,7 @@
{
struct kmem_cache *s = to_slab(kobj);
+ kfree(s->name);
kfree(s);
}