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

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

Cc: stable@vger.kernel.org Fixes: 7901c1a8effb ("KEYS: Implement binary asymmetric key ID handling") Signed-off-by: Thorsten Blum thorsten.blum@linux.dev --- Changes in v2: - Use check_add_overflow() and error out as suggested by Lukas - Update patch description - Add Fixes: tag and @stable for backporting - Link to v1: https://lore.kernel.org/lkml/20251007185220.234611-2-thorsten.blum@linux.dev... --- crypto/asymmetric_keys/asymmetric_type.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c index ba2d9d1ea235..bd96f799757d 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 +142,14 @@ 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); + if (check_add_overflow(len_1, len_2, &len)) + return ERR_PTR(-EOVERFLOW); + 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;