From 84c1cf62465e2fb0a692620dcfeb52323ab03d48 Mon Sep 17 00:00:00 2001 From: Pekka Enberg Date: Tue, 14 Sep 2010 23:21:12 +0300 Subject: [PATCH] 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 Cc: David Rientjes Reported-by: Linus Torvalds Signed-off-by: Pekka Enberg Conflicts: mm/slub.c --- mm/slub.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index 05674aac9294..42ce17304275 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -209,6 +209,7 @@ static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p) { return 0; } static inline void sysfs_slab_remove(struct kmem_cache *s) { + kfree(s->name); kfree(s); } @@ -3169,6 +3170,16 @@ void __init kmem_cache_init(void) 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 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, 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 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size, 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 @@ static void kmem_cache_release(struct kobject *kobj) { struct kmem_cache *s = to_slab(kobj); + kfree(s->name); kfree(s); } -- 2.20.1