diff options
| author | Kees Cook <keescook@chromium.org> | 2018-03-08 13:57:02 -0800 |
|---|---|---|
| committer | Herbert Xu <herbert@gondor.apana.org.au> | 2018-03-16 23:35:53 +0800 |
| commit | 14de52112ee70ca289fa77bf2d9cbc79fd2c811f (patch) | |
| tree | aadb21d93cde2da9a059f4660d8c8376485526c2 /crypto | |
| parent | b698a9f4c5c52317db486b069190c7e3d2b97e7e (diff) | |
| download | lwn-14de52112ee70ca289fa77bf2d9cbc79fd2c811f.tar.gz lwn-14de52112ee70ca289fa77bf2d9cbc79fd2c811f.zip | |
crypto: ecc - Remove stack VLA usage
On the quest to remove all VLAs from the kernel[1], this switches to
a pair of kmalloc regions instead of using the stack. This also moves
the get_random_bytes() after all allocations (and drops the needless
"nbytes" variable).
[1] https://lkml.org/lkml/2018/3/7/621
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
| -rw-r--r-- | crypto/ecc.c | 23 |
1 files changed, 17 insertions, 6 deletions
diff --git a/crypto/ecc.c b/crypto/ecc.c index 18f32f2a5e1c..9c066b5ac12d 100644 --- a/crypto/ecc.c +++ b/crypto/ecc.c @@ -1025,9 +1025,7 @@ int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits, { int ret = 0; struct ecc_point *product, *pk; - u64 priv[ndigits]; - u64 rand_z[ndigits]; - unsigned int nbytes; + u64 *priv, *rand_z; const struct ecc_curve *curve = ecc_get_curve(curve_id); if (!private_key || !public_key || !curve) { @@ -1035,14 +1033,22 @@ int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits, goto out; } - nbytes = ndigits << ECC_DIGITS_TO_BYTES_SHIFT; + priv = kmalloc_array(ndigits, sizeof(*priv), GFP_KERNEL); + if (!priv) { + ret = -ENOMEM; + goto out; + } - get_random_bytes(rand_z, nbytes); + rand_z = kmalloc_array(ndigits, sizeof(*rand_z), GFP_KERNEL); + if (!rand_z) { + ret = -ENOMEM; + goto kfree_out; + } pk = ecc_alloc_point(ndigits); if (!pk) { ret = -ENOMEM; - goto out; + goto kfree_out; } product = ecc_alloc_point(ndigits); @@ -1051,6 +1057,8 @@ int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits, goto err_alloc_product; } + get_random_bytes(rand_z, ndigits << ECC_DIGITS_TO_BYTES_SHIFT); + ecc_swap_digits(public_key, pk->x, ndigits); ecc_swap_digits(&public_key[ndigits], pk->y, ndigits); ecc_swap_digits(private_key, priv, ndigits); @@ -1065,6 +1073,9 @@ int crypto_ecdh_shared_secret(unsigned int curve_id, unsigned int ndigits, ecc_free_point(product); err_alloc_product: ecc_free_point(pk); +kfree_out: + kzfree(priv); + kzfree(rand_z); out: return ret; } |