From: Jianqun Xu jay.xu@rock-chips.com
mainline inclusion from mainline-v5.9-rc1 commit 835832ba01bb444c7e45139e4b807527c119dafc category: bugfix bugzilla: 41397 CVE: NA
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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 jay.xu@rock-chips.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Reviewed-by: David Hildenbrand david@redhat.com Link: http://lkml.kernel.org/r/20200615010123.15596-1-jay.xu@rock-chips.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Liu Shixin liushixin2@huawei.com Reviewed-by: Chen Wandun chenwandun@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- mm/cma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/cma.c b/mm/cma.c index 4c2864270a39b..f4df1bcbaf3ba 100644 --- a/mm/cma.c +++ b/mm/cma.c @@ -430,7 +430,7 @@ 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,