From: Stephan Mueller Subject: Re: [PATCH] crypto: af_alg - add async support to algif_aead Date: Thu, 28 Jan 2016 18:09:55 +0100 Message-ID: <3065480.xA9mO0V5SY@tauon.atsec.com> References: <20160127221031.12534.13202.stgit@tstruk-mobl1> <76537095.pjn76bZGgL@positron.chronox.de> <56AA3B19.8080604@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: herbert@gondor.apana.org.au, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org To: Tadeusz Struk Return-path: In-Reply-To: <56AA3B19.8080604@intel.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org Am Donnerstag, 28. Januar 2016, 08:00:25 schrieb Tadeusz Struk: Hi Tadeusz, >Hi Stephan, > >On 01/27/2016 10:26 PM, Stephan Mueller wrote: >>> + for (i = 0; i < areq->tsgls; i++) >>> >>> > + put_page(sg_page(sg + i)); >> >> Shouldn't here be the same logic as in put_sgl? I.e. >> >> for (i = 0; i < sgl->cur; i++) { >> >> if (!sg_page(sg + i)) >> >> continue; >> >> put_page(sg_page(sg + i)); >> sg_assign_page(sg + i, NULL); >> >> } > >Thanks for reviewing. >I don't think it is possible that there ever will be any gaps in the tsgl. >In fact if there is such a possibility then it is a serious problem, because >it would mean that we are sending NULL ptrs to the ciphers (see line 640): > > sg_mark_end(sgl->sg + sgl->cur - 1); > aead_request_set_crypt(&ctx->aead_req, sgl->sg, ctx- >first_rsgl.sgl.sg, > used, ctx->iv); > >I don't see any implementation checking for null in sgls. Most of them just >do: > > for_each_sg(sgl, sg, nents, i) > sg_virt(sg)... > >So it would Oops there. I think this check in put_sgl is redundant. >Thanks, algif_skcipher does a similar check in skcipher_pull_sgl: ... if (!sg_page(sg + i)) continue; ... if (put) put_page(sg_page(sg + i)); sg_assign_page(sg + i, NULL); ... Ciao Stephan