linux-kernel - [PATCH v3] crypto: DRBG - always try to free Jitter RNG instance

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Date:   Sun, 07 Jun 2020 15:20:26 +0200
From:   Stephan Müller <smueller@...onox.de>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     davem@...emloft.net, herbert@...dor.apana.org.au,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com,
        syzbot <syzbot+2e635807decef724a1fa@...kaller.appspotmail.com>,
        Eric Biggers <ebiggers@...nel.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: [PATCH v3] crypto: DRBG - always try to free Jitter RNG instance

The Jitter RNG is unconditionally allocated as a seed source follwoing
the patch 97f2650e5040. Thus, the instance must always be deallocated.

Reported-by: syzbot+2e635807decef724a1fa@...kaller.appspotmail.com
Fixes: 97f2650e5040 ("crypto: drbg - always seeded with SP800-90B ...")
Signed-off-by: Stephan Mueller <smueller@...onox.de>
---
 crypto/drbg.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/crypto/drbg.c b/crypto/drbg.c
index 37526eb8c5d5..8d80d93cab97 100644
--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1631,10 +1631,12 @@ static int drbg_uninstantiate(struct drbg_state *drbg)
 	if (drbg->random_ready.func) {
 		del_random_ready_callback(&drbg->random_ready);
 		cancel_work_sync(&drbg->seed_work);
-		crypto_free_rng(drbg->jent);
-		drbg->jent = NULL;
 	}
 
+	if (!IS_ERR_OR_NULL(drbg->jent))
+		crypto_free_rng(drbg->jent);
+	drbg->jent = NULL;
+
 	if (drbg->d_ops)
 		drbg->d_ops->crypto_fini(drbg);
 	drbg_dealloc_state(drbg);
-- 
2.26.2