If a list_for_each_entry() loop exits without hitting a break statement
then the iterator points to invalid memory. So in this code the
"tst->name" dereference is an out bounds read. It's an offset from the
&test_upload_list pointer and it will likely work fine most of the time
but it's not correct.
One alternative is to fix this this by changing the test to:
if (list_entry_is_head(tst, &test_upload_list, node)) {
But the simpler, trendy new way is just create a new variable and test
for NULL.
Fixes: a31ad463b72d ("test_firmware: Add test support for firmware upload")
Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
---
lib/test_firmware.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/lib/test_firmware.c b/lib/test_firmware.c
index 76115c1a2629..c82b65947ce6 100644
--- a/lib/test_firmware.c
+++ b/lib/test_firmware.c
@@ -1392,7 +1392,8 @@ static ssize_t upload_read_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
- struct test_firmware_upload *tst;
+ struct test_firmware_upload *tst = NULL;
+ struct test_firmware_upload *tst_iter;
int ret = -EINVAL;
if (!test_fw_config->upload_name) {
@@ -1401,11 +1402,13 @@ static ssize_t upload_read_show(struct device *dev,
}
mutex_lock(&test_fw_mutex);
- list_for_each_entry(tst, &test_upload_list, node)
- if (tst->name == test_fw_config->upload_name)
+ list_for_each_entry(tst_iter, &test_upload_list, node)
+ if (tst_iter->name == test_fw_config->upload_name) {
+ tst = tst_iter;
break;
+ }
- if (tst->name != test_fw_config->upload_name) {
+ if (!tst) {
pr_err("Firmware name not found: %s\n",
test_fw_config->upload_name);
goto out;
--
2.35.1
