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-rw-r--r--crypto/cts.c18
1 files changed, 11 insertions, 7 deletions
diff --git a/crypto/cts.c b/crypto/cts.c
index 4e28d83ae37d..9441da797bb9 100644
--- a/crypto/cts.c
+++ b/crypto/cts.c
@@ -152,12 +152,14 @@ static int crypto_cts_encrypt(struct skcipher_request *req)
struct skcipher_request *subreq = &rctx->subreq;
int bsize = crypto_skcipher_blocksize(tfm);
unsigned int nbytes = req->cryptlen;
- int cbc_blocks = (nbytes + bsize - 1) / bsize - 1;
unsigned int offset;
skcipher_request_set_tfm(subreq, ctx->child);
- if (cbc_blocks <= 0) {
+ if (nbytes < bsize)
+ return -EINVAL;
+
+ if (nbytes == bsize) {
skcipher_request_set_callback(subreq, req->base.flags,
req->base.complete,
req->base.data);
@@ -166,7 +168,7 @@ static int crypto_cts_encrypt(struct skcipher_request *req)
return crypto_skcipher_encrypt(subreq);
}
- offset = cbc_blocks * bsize;
+ offset = rounddown(nbytes - 1, bsize);
rctx->offset = offset;
skcipher_request_set_callback(subreq, req->base.flags,
@@ -244,13 +246,15 @@ static int crypto_cts_decrypt(struct skcipher_request *req)
struct skcipher_request *subreq = &rctx->subreq;
int bsize = crypto_skcipher_blocksize(tfm);
unsigned int nbytes = req->cryptlen;
- int cbc_blocks = (nbytes + bsize - 1) / bsize - 1;
unsigned int offset;
u8 *space;
skcipher_request_set_tfm(subreq, ctx->child);
- if (cbc_blocks <= 0) {
+ if (nbytes < bsize)
+ return -EINVAL;
+
+ if (nbytes == bsize) {
skcipher_request_set_callback(subreq, req->base.flags,
req->base.complete,
req->base.data);
@@ -264,10 +268,10 @@ static int crypto_cts_decrypt(struct skcipher_request *req)
space = crypto_cts_reqctx_space(req);
- offset = cbc_blocks * bsize;
+ offset = rounddown(nbytes - 1, bsize);
rctx->offset = offset;
- if (cbc_blocks <= 1)
+ if (offset <= bsize)
memcpy(space, req->iv, bsize);
else
scatterwalk_map_and_copy(space, req->src, offset - 2 * bsize,