Re: [PATCH v2 1/2] crypto: asymmetric_keys - prevent overflow in asymmetric_key_generate_id

On 13. Oct 2025, at 08:24, Lukas Wunner wrote:

On Sun, Oct 12, 2025 at 10:38:40PM +0200, Thorsten Blum wrote:

...

+++ b/crypto/asymmetric_keys/asymmetric_type.c @@ -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);

This will add (at least) 2 bytes to len (namely the size of struct asymmetric_key_id)) and may cause an overflow (even if len_1 + len_2 did not overflow).

Could you explain which part adds "(at least) 2 bytes to len"?

Thanks, Thorsten