linux-kernel - [PATCH 1/2] crypto: asymmetric_keys - prevent overflow in asymmetric_key_generate

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Message-ID: <20251007185220.234611-2-thorsten.blum@linux.dev>
Date: Tue,  7 Oct 2025 20:52:20 +0200
From: Thorsten Blum <thorsten.blum@...ux.dev>
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: Thorsten Blum <thorsten.blum@...ux.dev>,
	keyrings@...r.kernel.org,
	linux-crypto@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/2] crypto: asymmetric_keys - prevent overflow in asymmetric_key_generate_id

Use size_add() to prevent a potential integer overflow when adding the
binary blob lengths in asymmetric_key_generate_id(), which could cause a
buffer overflow when copying the data using memcpy().

Use struct_size() to calculate the number of bytes to allocate for the
new asymmetric key id.

No functional changes.

Signed-off-by: Thorsten Blum <thorsten.blum@...ux.dev>
---
 crypto/asymmetric_keys/asymmetric_type.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
index ba2d9d1ea235..aea925c88973 100644
--- a/crypto/asymmetric_keys/asymmetric_type.c
+++ b/crypto/asymmetric_keys/asymmetric_type.c
@@ -11,6 +11,7 @@
 #include <crypto/public_key.h>
 #include <linux/seq_file.h>
 #include <linux/module.h>
+#include <linux/overflow.h>
 #include <linux/slab.h>
 #include <linux/ctype.h>
 #include <keys/system_keyring.h>
@@ -141,12 +142,13 @@ struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
 						     size_t len_2)
 {
 	struct asymmetric_key_id *kid;
+	size_t len;
 
-	kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
-		      GFP_KERNEL);
+	len = size_add(len_1, len_2);
+	kid = kmalloc(struct_size(kid, data, len), GFP_KERNEL);
 	if (!kid)
 		return ERR_PTR(-ENOMEM);
-	kid->len = len_1 + len_2;
+	kid->len = len;
 	memcpy(kid->data, val_1, len_1);
 	memcpy(kid->data + len_1, val_2, len_2);
 	return kid;
-- 
2.51.0