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test_firmware: fix end of loop test in upload_read_show()

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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: a31ad463b7 ("test_firmware: Add test support for firmware upload")
Reviewed-by: Russ Weight <russell.h.weight@intel.com>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YnTGU3UJOIA09I7e@kili
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Dan Carpenter 2022-05-06 09:55:15 +03:00 committed by Greg Kroah-Hartman
parent 1f7ff11ca6
commit 185b29c615
1 changed files with 7 additions and 4 deletions
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11
lib/test_firmware.c
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@ -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;