crypto: powerpc/p10-aes-gcm - simplify handling of linear associated data

p10_aes_gcm_crypt() is abusing the scatter_walk API to get the virtual
address for the first source scatterlist element.  But this code is only
built for PPC64 which is a !HIGHMEM platform, and it can read past a
page boundary from the address returned by scatterwalk_map() which means
it already assumes the address is from the kernel's direct map.  Thus,
just use sg_virt() instead to get the same result in a simpler way.

Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Danny Tsen <dtsen@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

diff --git a/arch/powerpc/crypto/aes-gcm-p10-glue.c b/arch/powerpc/crypto/aes-gcm-p10-glue.c
index f37b3d13fc53094c38c9b3d90ceb884d6854884f..679f52794baffa8f22ff46a9e03775fb6462f1a8 100644 (file)
--- a/arch/powerpc/crypto/aes-gcm-p10-glue.c
+++ b/arch/powerpc/crypto/aes-gcm-p10-glue.c
@@ -214,7 +214,6 @@ static int p10_aes_gcm_crypt(struct aead_request *req, u8 *riv,
        struct gcm_ctx *gctx = PTR_ALIGN((void *)databuf, PPC_ALIGN);
        u8 hashbuf[sizeof(struct Hash_ctx) + PPC_ALIGN];
        struct Hash_ctx *hash = PTR_ALIGN((void *)hashbuf, PPC_ALIGN);
-       struct scatter_walk assoc_sg_walk;
        struct skcipher_walk walk;
        u8 *assocmem = NULL;
        u8 *assoc;
@@ -234,8 +233,7 @@ static int p10_aes_gcm_crypt(struct aead_request *req, u8 *riv,
 
        /* Linearize assoc, if not already linear */
        if (req->src->length >= assoclen && req->src->length) {
-               scatterwalk_start(&assoc_sg_walk, req->src);
-               assoc = scatterwalk_map(&assoc_sg_walk);
+               assoc = sg_virt(req->src); /* ppc64 is !HIGHMEM */
        } else {
                gfp_t flags = (req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP) ?
                              GFP_KERNEL : GFP_ATOMIC;
@@ -253,10 +251,7 @@ static int p10_aes_gcm_crypt(struct aead_request *req, u8 *riv,
        gcmp10_init(gctx, iv, (unsigned char *) &ctx->enc_key, hash, assoc, assoclen);
        vsx_end();
 
-       if (!assocmem)
-               scatterwalk_unmap(assoc);
-       else
-               kfree(assocmem);
+       kfree(assocmem);
 
        if (enc)
                ret = skcipher_walk_aead_encrypt(&walk, req, false);