The function CRYPTO_128_unwrap_pad uses an 8 byte AIV (Alternative Initial
Value). The least significant 4 bytes of this is placed into the local
variable |ptext_len|. This is done as follows:
ptext_len = (aiv[4] << 24) | (aiv[5] << 16) | (aiv[6] << 8) | aiv[7];
aiv[4] is an unsigned char, but (aiv[4] << 24) is promoted to a *signed*
int - therefore we could end up shifting into the sign bit and end up with
a negative value. |ptext_len| is a size_t (typically 64-bits). If the
result of the shifts is negative then the upper bits of |ptext_len| will
all be 1.
This commit fixes the issue by explicitly casting to an unsigned int.
Reviewed-by: Richard Levitte <levitte@openssl.org>
* LSB(32,AIV).
*/
- ptext_len = (aiv[4] << 24) | (aiv[5] << 16) | (aiv[6] << 8) | aiv[7];
+ ptext_len = ((unsigned int)aiv[4] << 24)
+ | ((unsigned int)aiv[5] << 16)
+ | ((unsigned int)aiv[6] << 8)
+ | (unsigned int)aiv[7];
if (8 * (n - 1) >= ptext_len || ptext_len > 8 * n) {
OPENSSL_cleanse(out, inlen);
return 0;