Replaced old manual mutex locking/unlocking with
new safe guard(mutex) in drbg_instantiate().
This ensures mutex gets unlocked on every return and prevents deadlocks.

Signed-off-by: Rajveer Chaudhari <rajveer.chaudhari.linux@gmail.com>
---
 crypto/drbg.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/crypto/drbg.c b/crypto/drbg.c
index 1d433dae9955..d52a7bd07322 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -103,6 +103,7 @@
 #include <linux/kernel.h>
 #include <linux/jiffies.h>
 #include <linux/string_choices.h>
+#include <linux/cleanup.h>
 
 /***************************************************************
  * Backend cipher definitions available to DRBG
@@ -1349,7 +1350,7 @@ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
 
 	pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
 		 "%s\n", coreref, str_enabled_disabled(pr));
-	mutex_lock(&drbg->drbg_mutex);
+	guard(mutex)(&drbg->drbg_mutex);
 
 	/* 9.1 step 1 is implicit with the selected DRBG type */
 
@@ -1370,7 +1371,7 @@ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
 
 		ret = drbg_alloc_state(drbg);
 		if (ret)
-			goto unlock;
+			return ret;
 
 		ret = drbg_prepare_hrng(drbg);
 		if (ret)
@@ -1384,15 +1385,9 @@ static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
 	if (ret && !reseed)
 		goto free_everything;
 
-	mutex_unlock(&drbg->drbg_mutex);
-	return ret;
-
-unlock:
-	mutex_unlock(&drbg->drbg_mutex);
 	return ret;
 
 free_everything:
-	mutex_unlock(&drbg->drbg_mutex);
 	drbg_uninstantiate(drbg);
 	return ret;
 }
-- 
2.52.0