mm/cma.c: fix NULL pointer dereference when cma could not be activated

In some case the cma area could not be activated, but the cma_alloc be used under this case, then the kernel will crash caused by NULL pointer dereference. Add bitmap valid check in cma_alloc to avoid this issue. Signed-off-by: Jianqun Xu <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Reviewed-by: David Hildenbrand <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Linus Torvalds <[email protected]>
kawasaki · Aug 12, 2020 · 835832b · 835832b
1 parent 1a5bae2
commit 835832b
Showing 1 changed file with 1 addition and 1 deletion.
diff --git a/mm/cma.c b/mm/cma.c
@@ -425,7 +425,7 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
 	struct page *page = NULL;
 	int ret = -ENOMEM;
 
-	if (!cma || !cma->count)
+	if (!cma || !cma->count || !cma->bitmap)
 		return NULL;
 
 	pr_debug("%s(cma %p, count %zu, align %d)\n", __func__, (void *)cma,