[PATCH] mm/vmalloc: fix unsafe dereference of potential null ptr in vmalloc_init()

[PATCH] mm/vmalloc: fix unsafe dereference of potential null ptr in vmalloc_init()

[Alexander Sapozhnikov]

Return value of a function 'kmem_cache_create' is dereferenced 
at vmalloc.c:2444 without checking for null, but it is usually 
checked for this function.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Signed-off-by: Alexander Sapozhnikov <alsp705@gmail.com>
---
 mm/vmalloc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ca71de7c9d77..ed75dfd44b85 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2426,6 +2426,8 @@ void __init vmalloc_init(void)
 	 * Create the cache for vmap_area objects.
 	 */
 	vmap_area_cachep = KMEM_CACHE(vmap_area, SLAB_PANIC);
+	if (!vmap_area_cachep)
+		return;
 
 	for_each_possible_cpu(i) {
 		struct vmap_block_queue *vbq;
-- 
2.34.1

Re: [PATCH] mm/vmalloc: fix unsafe dereference of potential null ptr in vmalloc_init()

[Christoph Hellwig]

On Fri, Feb 17, 2023 at 03:51:05PM +0300, Alexander Sapozhnikov wrote:
> Return value of a function 'kmem_cache_create' is dereferenced 
> at vmalloc.c:2444 without checking for null, but it is usually 
> checked for this function.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.

I think that checker needs to learn about SLAB_PANIC..