From 835832ba01bb444c7e45139e4b807527c119dafc Mon Sep 17 00:00:00 2001 From: Jianqun Xu Date: Tue, 11 Aug 2020 18:31:54 -0700 Subject: [PATCH] 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 Signed-off-by: Andrew Morton Reviewed-by: David Hildenbrand Link: http://lkml.kernel.org/r/20200615010123.15596-1-jay.xu@rock-chips.com Signed-off-by: Linus Torvalds --- mm/cma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/cma.c b/mm/cma.c index 26ecff818881..3a18f8d8ea5e 100644 --- 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,