[PATCH v1 1/1] test_firmware: fix a memory leak with reqs buffer

[Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>]

[ commit be37bed754ed90b2655382f93f9724b3c1aae847 upstream ]

Dan Carpenter spotted that test_fw_config->reqs will be leaked if
trigger_batched_requests_store() is called two or more times.
The same appears with trigger_batched_requests_async_store().

This bug wasn't triggered by the tests, but observed by Dan's visual
inspection of the code.

The recommended workaround was to return -EBUSY if test_fw_config->reqs
is already allocated.

Fixes: c92316bf8e94 ("test_firmware: add batched firmware tests")
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Russ Weight <russell.h.weight@intel.com>
Cc: Tianfei Zhang <tianfei.zhang@intel.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Colin Ian King <colin.i.king@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-kselftest@vger.kernel.org
Cc: stable@vger.kernel.org # v4.19
Suggested-by: Dan Carpenter <error27@gmail.com>
Suggested-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Link: https://lore.kernel.org/r/20230509084746.48259-2-mirsad.todorovac@alu.unizg.hr
Signed-off-by: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>

[ This is a backport to v4.19 stable branch without a change in code from the 5.4+ patch ]
---
v1:
 patch sumbmitted verbatim from the 5.4+ branch to 4.19

 lib/test_firmware.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/test_firmware.c b/lib/test_firmware.c
index f4cc874021da..e4688821eab8 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -618,6 +618,11 @@ static ssize_t trigger_batched_requests_store(struct device *dev,
 
 	mutex_lock(&test_fw_mutex);
 
+	if (test_fw_config->reqs) {
+		rc = -EBUSY;
+		goto out_bail;
+	}
+
 	test_fw_config->reqs =
 		vzalloc(array3_size(sizeof(struct test_batched_req),
 				    test_fw_config->num_requests, 2));
@@ -721,6 +726,11 @@ ssize_t trigger_batched_requests_async_store(struct device *dev,
 
 	mutex_lock(&test_fw_mutex);
 
+	if (test_fw_config->reqs) {
+		rc = -EBUSY;
+		goto out_bail;
+	}
+
 	test_fw_config->reqs =
 		vzalloc(array3_size(sizeof(struct test_batched_req),
 				    test_fw_config->num_requests, 2));
-- 
2.34.1