crypto: algif_skcipher - Handle unaligned receive buffer

As it is if user-space passes through a receive buffer that's not
aligned to to the cipher block size, we'll end up encrypting or
decrypting a partial block which causes a spurious EINVAL to be
returned.

This patch fixes this by moving the partial block test after the
af_alg_make_sg call.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 7 insertions, 6 deletions

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 1f33480e3260..6a6dfc062d2a 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -454,17 +454,17 @@ static int skcipher_recvmsg(struct kiocb *unused, struct socket *sock,
 
                         used = min_t(unsigned long, used, seglen);
 
+                        used = af_alg_make_sg(&ctx->rsgl, from, used, 1);
+                        err = used;
+                        if (err < 0)
+                                goto unlock;
+
                         if (ctx->more || used < ctx->used)
                                 used -= used % bs;
 
                         err = -EINVAL;
                         if (!used)
-                                goto unlock;
-
-                        used = af_alg_make_sg(&ctx->rsgl, from, used, 1);
-                        err = used;
-                        if (err < 0)
-                                goto unlock;
+                                goto free;
 
                         ablkcipher_request_set_crypt(&ctx->req, sg,
                                                      ctx->rsgl.sg, used,
@@ -476,6 +476,7 @@ static int skcipher_recvmsg(struct kiocb *unused, struct socket *sock,
                                         crypto_ablkcipher_decrypt(&ctx->req),
                                 &ctx->completion);
 
+free:
                         af_alg_free_sg(&ctx->rsgl);
 
                         if (err)