[PATCH] hwrng: core - reject unknown RNG names

[Thorsten Blum <blum@kernel.org>]

In rng_current_store(), err is 0 after successfully locking rng_mutex,
and if the requested RNG name cannot be found, the function reports
success even though the current RNG was not changed.

Set err = -ENODEV before searching the RNG list to reject unknown names.

Fixes: 142a27f0a731 ("hwrng: core - Reset user selected rng by writing "" to rng_current")
Cc: stable@vger.kernel.org
Signed-off-by: Thorsten Blum <blum@kernel.org>
---
 drivers/char/hw_random/core.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index 57eeefe90da9..1f9e31cdc7f0 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -376,6 +376,7 @@ static ssize_t rng_current_store(struct device *dev,
 		cur_rng_set_by_user = 1;
 		drop_current_rng();
 	} else {
+		err = -ENODEV;
 		list_for_each_entry(rng, &rng_list, list) {
 			if (sysfs_streq(rng->name, buf)) {
 				err = set_current_rng(rng);