crypto: ecc - Actually remove stack VLA usage
On the quest to remove all VLAs from the kernel[1], this avoids VLAs
by just using the maximum allocation size (4 bytes) for stack arrays.
All the VLAs in ecc were either 3 or 4 bytes (or a multiple), so just
make it 4 bytes all the time. Initialization routines are adjusted to
check that ndigits does not end up larger than the arrays.
This includes a removal of the earlier attempt at this fix from
commit a963834b4742 ("crypto/ecc: Remove stack VLA usage")
[1] https://lkml.org/lkml/2018/3/7/621
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/crypto/ecdh.c b/crypto/ecdh.c
index d2ec33f..bf63001 100644
--- a/crypto/ecdh.c
+++ b/crypto/ecdh.c
@@ -30,8 +30,8 @@
static unsigned int ecdh_supported_curve(unsigned int curve_id)
{
switch (curve_id) {
- case ECC_CURVE_NIST_P192: return 3;
- case ECC_CURVE_NIST_P256: return 4;
+ case ECC_CURVE_NIST_P192: return ECC_CURVE_NIST_P192_DIGITS;
+ case ECC_CURVE_NIST_P256: return ECC_CURVE_NIST_P256_DIGITS;
default: return 0;
}
}