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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 <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>
This commit is contained in:
Jianqun Xu 2020-08-11 18:31:54 -07:00 committed by Linus Torvalds
parent 1a5bae25e3
commit 835832ba01
1 changed files with 1 additions and 1 deletions
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mm/cma.c
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@ -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,