We avoid 3 VLAs[1] by always allocating MAX_BLOCKSIZE bytes or, when needed for alignement, MAX_BLOCKSIZE + MAX_ALIGNMASK bytes. We also check the selected cipher at instance creation time, if it doesn't comply with these limits, the creation will fail.
[1] http://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qpxydaacu1rq...@mail.gmail.com Signed-off-by: Salvatore Mesoraca <s.mesorac...@gmail.com> --- crypto/cfb.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/crypto/cfb.c b/crypto/cfb.c index 94ee39b..f500816 100644 --- a/crypto/cfb.c +++ b/crypto/cfb.c @@ -28,6 +28,7 @@ #include <linux/slab.h> #include <linux/string.h> #include <linux/types.h> +#include "internal.h" struct crypto_cfb_ctx { struct crypto_cipher *child; @@ -53,9 +54,8 @@ static void crypto_cfb_encrypt_one(struct crypto_skcipher *tfm, static void crypto_cfb_final(struct skcipher_walk *walk, struct crypto_skcipher *tfm) { - const unsigned int bsize = crypto_cfb_bsize(tfm); const unsigned long alignmask = crypto_skcipher_alignmask(tfm); - u8 tmp[bsize + alignmask]; + u8 tmp[MAX_BLOCKSIZE + MAX_ALIGNMASK]; u8 *stream = PTR_ALIGN(tmp + 0, alignmask + 1); u8 *src = walk->src.virt.addr; u8 *dst = walk->dst.virt.addr; @@ -94,7 +94,7 @@ static int crypto_cfb_encrypt_inplace(struct skcipher_walk *walk, unsigned int nbytes = walk->nbytes; u8 *src = walk->src.virt.addr; u8 *iv = walk->iv; - u8 tmp[bsize]; + u8 tmp[MAX_BLOCKSIZE]; do { crypto_cfb_encrypt_one(tfm, iv, tmp); @@ -164,7 +164,7 @@ static int crypto_cfb_decrypt_inplace(struct skcipher_walk *walk, unsigned int nbytes = walk->nbytes; u8 *src = walk->src.virt.addr; u8 *iv = walk->iv; - u8 tmp[bsize]; + u8 tmp[MAX_BLOCKSIZE]; do { crypto_cfb_encrypt_one(tfm, iv, tmp); @@ -295,6 +295,12 @@ static int crypto_cfb_create(struct crypto_template *tmpl, struct rtattr **tb) if (err) goto err_drop_spawn; + err = -EINVAL; + if (alg->cra_blocksize > MAX_BLOCKSIZE) + goto err_drop_spawn; + if (alg->cra_alignmask > MAX_ALIGNMASK) + goto err_drop_spawn; + inst->alg.base.cra_priority = alg->cra_priority; /* we're a stream cipher independend of the crypto cra_blocksize */ inst->alg.base.cra_blocksize = 1; -- 1.9.1
