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crypto: ecc - Actually remove stack VLA usage

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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>
This commit is contained in:
Kees Cook
2018-03-30 09:55:44 -07:00
committed by Herbert Xu
parent 3a488aaec6
commit d5c3b17898
3 changed files with 33 additions and 41 deletions
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4
crypto/ecc.h
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@@ -26,7 +26,9 @@
#ifndef _CRYPTO_ECC_H
#define _CRYPTO_ECC_H
#define ECC_MAX_DIGITS 4 /* 256 */
#define ECC_CURVE_NIST_P192_DIGITS 3
#define ECC_CURVE_NIST_P256_DIGITS 4
#define ECC_MAX_DIGITS ECC_CURVE_NIST_P256_DIGITS
#define ECC_DIGITS_TO_BYTES_SHIFT 3