[PATCH 5.4 097/134] mmc: mmc_test: Fix NULL dereference on allocation failure

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5.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

[ Upstream commit a1e627af32ed60713941cbfc8075d44cad07f6dd ]

If the "test->highmem = alloc_pages()" allocation fails then calling
__free_pages(test->highmem) will result in a NULL dereference.  Also
change the error code to -ENOMEM instead of returning success.

Fixes: 2661081f5ab9 ("mmc_test: highmem tests")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Link: https://lore.kernel.org/r/8c90be28-67b4-4b0d-a105-034dc72a0b31@stanley.mountain
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/mmc/core/mmc_test.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/core/mmc_test.c b/drivers/mmc/core/mmc_test.c
index cd64e0f23ae54..8fcaec5544ff4 100644
--- a/drivers/mmc/core/mmc_test.c
+++ b/drivers/mmc/core/mmc_test.c
@@ -3097,13 +3097,13 @@ static ssize_t mtf_test_write(struct file *file, const char __user *buf,
 	test->buffer = kzalloc(BUFFER_SIZE, GFP_KERNEL);
 #ifdef CONFIG_HIGHMEM
 	test->highmem = alloc_pages(GFP_KERNEL | __GFP_HIGHMEM, BUFFER_ORDER);
+	if (!test->highmem) {
+		count = -ENOMEM;
+		goto free_test_buffer;
+	}
 #endif
 
-#ifdef CONFIG_HIGHMEM
-	if (test->buffer && test->highmem) {
-#else
 	if (test->buffer) {
-#endif
 		mutex_lock(&mmc_test_lock);
 		mmc_test_run(test, testcase);
 		mutex_unlock(&mmc_test_lock);
@@ -3111,6 +3111,7 @@ static ssize_t mtf_test_write(struct file *file, const char __user *buf,
 
 #ifdef CONFIG_HIGHMEM
 	__free_pages(test->highmem, BUFFER_ORDER);
+free_test_buffer:
 #endif
 	kfree(test->buffer);
 	kfree(test);
-- 
2.43.0







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