linux-kernel - [PATCH] crypto: asymmetric_keys: fix uninitialized pointers with free attr

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Message-Id: <20251105-aheev-uninitialized-free-attr-crypto-v1-1-83da1e10e8c4@gmail.com>
Date: Wed, 05 Nov 2025 15:23:08 +0530
From: Ally Heev <allyheev@...il.com>
To: David Howells <dhowells@...hat.com>, Lukas Wunner <lukas@...ner.de>, 
 Ignat Korchagin <ignat@...udflare.com>, 
 Herbert Xu <herbert@...dor.apana.org.au>, 
 "David S. Miller" <davem@...emloft.net>
Cc: keyrings@...r.kernel.org, linux-crypto@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Dan Carpenter <dan.carpenter@...aro.org>, 
 Ally Heev <allyheev@...il.com>
Subject: [PATCH] crypto: asymmetric_keys: fix uninitialized pointers with
 free attr

Uninitialized pointers with `__free` attribute can cause undefined
behaviour as the memory assigned(randomly) to the pointer is freed
automatically when the pointer goes out of scope

crypto/asymmetric_keys doesn't have any bugs related to this as of now,
but, it is better to initialize and assign pointers with `__free` attr
in one statement to ensure proper scope-based cleanup

Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
Closes: https://lore.kernel.org/all/aPiG_F5EBQUjZqsl@stanley.mountain/
Signed-off-by: Ally Heev <allyheev@...il.com>
---
 crypto/asymmetric_keys/x509_cert_parser.c | 11 +++++++----
 crypto/asymmetric_keys/x509_public_key.c  | 14 ++++++++------
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 8df3fa60a44f80fbd71af17faeca2e92b6cc03ce..bfd2cb2a9d81e3c615dfd4fe6f41653869a8cbd6 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -60,12 +60,12 @@ EXPORT_SYMBOL_GPL(x509_free_certificate);
  */
 struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
 {
-	struct x509_certificate *cert __free(x509_free_certificate);
-	struct x509_parse_context *ctx __free(kfree) = NULL;
 	struct asymmetric_key_id *kid;
 	long ret;
 
-	cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
+	struct x509_certificate *cert __free(x509_free_certificate) = kzalloc(
+		sizeof(struct x509_certificate), GFP_KERNEL);
+
 	if (!cert)
 		return ERR_PTR(-ENOMEM);
 	cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
@@ -74,7 +74,10 @@ struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
 	cert->sig = kzalloc(sizeof(struct public_key_signature), GFP_KERNEL);
 	if (!cert->sig)
 		return ERR_PTR(-ENOMEM);
-	ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
+
+	struct x509_parse_context *ctx __free(kfree) = kzalloc(
+		sizeof(struct x509_parse_context), GFP_KERNEL);
+
 	if (!ctx)
 		return ERR_PTR(-ENOMEM);
 
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 8409d7d36cb4f3582e15f9ee4d25f302b3b29358..818c9ab5d63940ff62c21666fd549d3a1ff07e67 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -148,13 +148,13 @@ int x509_check_for_self_signed(struct x509_certificate *cert)
  */
 static int x509_key_preparse(struct key_preparsed_payload *prep)
 {
-	struct x509_certificate *cert __free(x509_free_certificate);
-	struct asymmetric_key_ids *kids __free(kfree) = NULL;
-	char *p, *desc __free(kfree) = NULL;
+	char *p;
 	const char *q;
 	size_t srlen, sulen;
 
-	cert = x509_cert_parse(prep->data, prep->datalen);
+	struct x509_certificate *cert __free(x509_free_certificate) =
+		x509_cert_parse(prep->data, prep->datalen);
+
 	if (IS_ERR(cert))
 		return PTR_ERR(cert);
 
@@ -187,7 +187,7 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
 		q = cert->raw_serial;
 	}
 
-	desc = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
+	char *desc __free(kfree) = kmalloc(sulen + 2 + srlen * 2 + 1, GFP_KERNEL);
 	if (!desc)
 		return -ENOMEM;
 	p = memcpy(desc, cert->subject, sulen);
@@ -197,7 +197,9 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
 	p = bin2hex(p, q, srlen);
 	*p = 0;
 
-	kids = kmalloc(sizeof(struct asymmetric_key_ids), GFP_KERNEL);
+	struct asymmetric_key_ids *kids __free(kfree) = kmalloc(
+		sizeof(struct asymmetric_key_ids), GFP_KERNEL);
+
 	if (!kids)
 		return -ENOMEM;
 	kids->id[0] = cert->id;

---
base-commit: c9cfc122f03711a5124b4aafab3211cf4d35a2ac
change-id: 20251105-aheev-uninitialized-free-attr-crypto-bc94ec1b2253

Best regards,
-- 
Ally Heev <allyheev@...il.com>