linux-kernel - [PATCH] crypto: af_alg - Decrement struct key.usage in alg_set_by_key

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Message-Id: <20230801135709.2218855-1-fred@cloudflare.com>
Date:   Tue,  1 Aug 2023 08:57:09 -0500
From:   Frederick Lawler <fred@...udflare.com>
To:     herbert@...dor.apana.org.au, davem@...emloft.net
Cc:     linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org,
        kernel-team@...udflare.com, Frederick Lawler <fred@...udflare.com>,
        stable@...r.kernel.org
Subject: [PATCH] crypto: af_alg - Decrement struct key.usage in alg_set_by_key_serial()

Calls to lookup_user_key() require a corresponding key_put() to
decrement the usage counter. Once it reaches zero, we schedule key GC.
Therefore decrement struct key.usage in alg_set_by_key_serial().

Fixes: 7984ceb134bf ("crypto: af_alg - Support symmetric encryption via keyring keys")
Cc: <stable@...r.kernel.org>
Signed-off-by: Frederick Lawler <fred@...udflare.com>
---
This is rebased ontop of Linus's 6.5-rc1. Original patch was introduced in 6.2.
---
 crypto/af_alg.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/crypto/af_alg.c b/crypto/af_alg.c
index 6218c773d71c..295ede1996a4 100644
--- a/crypto/af_alg.c
+++ b/crypto/af_alg.c
@@ -320,18 +320,21 @@ static int alg_setkey_by_key_serial(struct alg_sock *ask, sockptr_t optval,
 
 	if (IS_ERR(ret)) {
 		up_read(&key->sem);
+		key_put(key);
 		return PTR_ERR(ret);
 	}
 
 	key_data = sock_kmalloc(&ask->sk, key_datalen, GFP_KERNEL);
 	if (!key_data) {
 		up_read(&key->sem);
+		key_put(key);
 		return -ENOMEM;
 	}
 
 	memcpy(key_data, ret, key_datalen);
 
 	up_read(&key->sem);
+	key_put(key);
 
 	err = type->setkey(ask->private, key_data, key_datalen);
 
-- 
2.34.1