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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        syzbot+2e635807decef724a1fa@syzkaller.appspotmail.com,
        Stephan Mueller <smueller@chronox.de>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "Jason A. Donenfeld" <Jason@zx2c4.com>
Subject: [PATCH 4.19 176/234] crypto: drbg - always try to free Jitter RNG instance
Date:   Thu, 23 Jun 2022 18:44:03 +0200
Message-Id: <20220623164348.031978813@linuxfoundation.org>
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From: "Stephan M?ller" <smueller@chronox.de>

commit 819966c06b759022e9932f328284314d9272b9f3 upstream.

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@syzkaller.appspotmail.com
Fixes: 97f2650e5040 ("crypto: drbg - always seeded with SP800-90B ...")
Signed-off-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 crypto/drbg.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/crypto/drbg.c
+++ b/crypto/drbg.c
@@ -1644,10 +1644,12 @@ static int drbg_uninstantiate(struct drb
 	if (drbg->random_ready.notifier_call) {
 		unregister_random_ready_notifier(&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);