On Thu, Jan 02, 2025 at 12:50:50PM +0100, Christophe Leroy wrote:
>
>
> Le 30/12/2024 à 01:13, Eric Biggers a écrit :
> > From: Eric Biggers <ebiggers@xxxxxxxxxx>
> >
> > 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@xxxxxxxxxx>
> > Cc: Danny Tsen <dtsen@xxxxxxxxxxxxx>
> > Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> > Cc: Naveen N Rao <naveen@xxxxxxxxxx>
> > Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
> > Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
> > Signed-off-by: Eric Biggers <ebiggers@xxxxxxxxxx>
> > ---
> >
> > This patch is part of a long series touching many files, so I have
> > limited the Cc list on the full series. If you want the full series and
> > did not receive it, please retrieve it from lore.kernel.org.
> >
> > arch/powerpc/crypto/aes-gcm-p10-glue.c | 8 ++------
> > 1 file changed, 2 insertions(+), 6 deletions(-)
> >
> > diff --git a/arch/powerpc/crypto/aes-gcm-p10-glue.c b/arch/powerpc/crypto/aes-gcm-p10-glue.c
> > index f37b3d13fc53..2862c3cf8e41 100644
> > --- a/arch/powerpc/crypto/aes-gcm-p10-glue.c
> > +++ b/arch/powerpc/crypto/aes-gcm-p10-glue.c
> > @@ -212,11 +212,10 @@ static int p10_aes_gcm_crypt(struct aead_request *req, u8 *riv,
> > struct p10_aes_gcm_ctx *ctx = crypto_tfm_ctx(tfm);
> > u8 databuf[sizeof(struct gcm_ctx) + PPC_ALIGN];
> > 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;
> > unsigned int cryptlen = req->cryptlen;
> > unsigned char ivbuf[AES_BLOCK_SIZE+PPC_ALIGN];
> > @@ -232,12 +231,11 @@ static int p10_aes_gcm_crypt(struct aead_request *req, u8 *riv,
> > memset(ivbuf, 0, sizeof(ivbuf));
> > memcpy(iv, riv, GCM_IV_SIZE);
> > /* 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;
> > /* assoc can be any length, so must be on heap */
> > @@ -251,13 +249,11 @@ static int p10_aes_gcm_crypt(struct aead_request *req, u8 *riv,
> > vsx_begin();
> > gcmp10_init(gctx, iv, (unsigned char *) &ctx->enc_key, hash, assoc, assoclen);
> > vsx_end();
> > - if (!assocmem)
> > - scatterwalk_unmap(assoc);
> > - else
> > + if (assocmem)
> > kfree(assocmem);
>
> kfree() accepts a NULL pointer, you can call kfree(assocmem) without 'if
> (assocmem)'
The existing code did that too, but sure I'll change that in v3.
- Eric
