linux-kernel - [PATCH] mm/vmalloc: fix unsafe dereference of potential null ptr in vmalloc

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Date:   Fri, 17 Feb 2023 15:51:05 +0300
From:   Alexander Sapozhnikov <alsp705@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Alexander Sapozhnikov <alsp705@...il.com>,
        Uladzislau Rezki <urezki@...il.com>,
        Christoph Hellwig <hch@...radead.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, lvc-project@...uxtesting.org
Subject: [PATCH] mm/vmalloc: fix unsafe dereference of potential null ptr in vmalloc_init()

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@...il.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