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crypto: asymmetric_keys - prevent overflow in asymmetric_key_generate_id

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Use check_add_overflow() to guard against potential integer overflows
when adding the binary blob lengths and the size of an asymmetric_key_id
structure and return ERR_PTR(-EOVERFLOW) accordingly. This prevents a
possible buffer overflow when copying data from potentially malicious
X.509 certificate fields that can be arbitrarily large, such as ASN.1
INTEGER serial numbers, issuer names, etc.

Fixes: 7901c1a8ef ("KEYS: Implement binary asymmetric key ID handling")
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This commit is contained in:
Thorsten Blum
2025-10-13 13:40:10 +02:00
committed by Herbert Xu
parent 77cd921027
commit df0845cf44
1 changed files with 9 additions and 3 deletions
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12
crypto/asymmetric_keys/asymmetric_type.c
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@@ -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 +142,17 @@ struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
size_t len_2)
{
struct asymmetric_key_id *kid;
size_t kid_sz;
size_t len;
kid = kmalloc(sizeof(struct asymmetric_key_id) + len_1 + len_2,
GFP_KERNEL);
if (check_add_overflow(len_1, len_2, &len))
return ERR_PTR(-EOVERFLOW);
if (check_add_overflow(sizeof(struct asymmetric_key_id), len, &kid_sz))
return ERR_PTR(-EOVERFLOW);
kid = kmalloc(kid_sz, 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;