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From: Colin King <>
To: Andrew Morton <>,
	Minchan Kim <>,
	John Hubbard <>,
	Stephen Rothwell <>,
	Greg Kroah-Hartman <>,
Subject: [PATCH] mm: cma: Fix potential null dereference on pointer cma
Date: Tue, 16 Mar 2021 10:04:33 +0000	[thread overview]
Message-ID: <> (raw)

From: Colin Ian King <>

At the start of the function there is a null pointer check on cma
and then branch to error handling label 'out'.  The subsequent call
to cma_sysfs_fail_pages_count dereferences cma, hence there is a
potential null pointer deference issue.  Fix this by only calling
cma_sysfs_fail_pages_count if cma is not null.

Addresses-Coverity: ("Dereference after null check")
Fixes: dc4764f7e9ac ("mm: cma: support sysfs")
Signed-off-by: Colin Ian King <>
 mm/cma.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/cma.c b/mm/cma.c
index 6d4dbafdb318..90e27458ddb7 100644
--- a/mm/cma.c
+++ b/mm/cma.c
@@ -512,7 +512,8 @@ struct page *cma_alloc(struct cma *cma, size_t count, unsigned int align,
 		cma_sysfs_alloc_pages_count(cma, count);
 	} else {
-		cma_sysfs_fail_pages_count(cma, count);
+		if (cma)
+			cma_sysfs_fail_pages_count(cma, count);
 	return page;

             reply	other threads:[~2021-03-16 10:04 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-16 10:04 Colin King [this message]
2021-03-16 18:09 ` [PATCH] mm: cma: Fix potential null dereference on pointer cma Minchan Kim
2021-03-17  7:13 ` John Hubbard

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