From: Krzysztof Kozlowski Subject: Re: [PATCH 1/4] crypto: s5p-sss: Fix race in error handling Date: Mon, 17 Sep 2018 14:59:52 +0200 Message-ID: References: <1536825522-6027-1-git-send-email-c.manszewski@samsung.com> <20180913075857eucas1p2cbccf3cd452a23eb46a234acb37b3a44~T5q8CpLOD2420024200eucas1p24@eucas1p2.samsung.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Cc: linux-crypto@vger.kernel.org, vz@mleia.com, k.konieczny@partner.samsung.com, herbert@gondor.apana.org.au, davem@davemloft.net, "linux-samsung-soc@vger.kernel.org" , linux-kernel@vger.kernel.org To: c.manszewski@samsung.com Return-path: In-Reply-To: <20180913075857eucas1p2cbccf3cd452a23eb46a234acb37b3a44~T5q8CpLOD2420024200eucas1p24@eucas1p2.samsung.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org On Thu, 13 Sep 2018 at 09:59, Christoph Manszewski wrote: > > Remove a race condition introduced by error path in functions: > s5p_aes_interrupt and s5p_aes_crypt_start. Setting the busy field of > struct s5p_aes_dev to false made it possible for s5p_tasklet_cb to > change the req field, before s5p_aes_complete was called. Nice catch. Indeed the code looks racy. > > Change the first parameter of s5p_aes_complete to struct > ablkcipher_request. Before spin_unlock, make a copy of the currently > handled request, to ensure s5p_aes_complete function call with the > correct request. > > Signed-off-by: Christoph Manszewski > --- > drivers/crypto/s5p-sss.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/drivers/crypto/s5p-sss.c b/drivers/crypto/s5p-sss.c > index faa282074e5a..0cf3f12d8f74 100644 > --- a/drivers/crypto/s5p-sss.c > +++ b/drivers/crypto/s5p-sss.c > @@ -475,9 +475,9 @@ static void s5p_sg_done(struct s5p_aes_dev *dev) > } > > /* Calls the completion. Cannot be called with dev->lock hold. */ > -static void s5p_aes_complete(struct s5p_aes_dev *dev, int err) > +static void s5p_aes_complete(struct ablkcipher_request *req, int err) > { > - dev->req->base.complete(&dev->req->base, err); > + req->base.complete(&req->base, err); > } > > static void s5p_unset_outdata(struct s5p_aes_dev *dev) > @@ -655,6 +655,7 @@ static irqreturn_t s5p_aes_interrupt(int irq, void *dev_id) > { > struct platform_device *pdev = dev_id; > struct s5p_aes_dev *dev = platform_get_drvdata(pdev); > + struct ablkcipher_request *req; > int err_dma_tx = 0; > int err_dma_rx = 0; > int err_dma_hx = 0; > @@ -725,9 +726,10 @@ static irqreturn_t s5p_aes_interrupt(int irq, void *dev_id) > if (err_dma_hx == 1) > s5p_set_dma_hashdata(dev, dev->hash_sg_iter); > > + req = dev->req; In this path it should not be needed, so just s5p_aes_complete(dev->req)? At this point dev->busy is true so s5p_aes_handle_req() will exit before starting new tasklet. Also the interrupt is an effect of finishing work by device scheduled in last tasklet... so obviously no tasklet should be running. > spin_unlock_irqrestore(&dev->lock, flags); > > - s5p_aes_complete(dev, 0); > + s5p_aes_complete(req, 0); > /* Device is still busy */ > tasklet_schedule(&dev->tasklet); > } else { > @@ -755,8 +757,9 @@ static irqreturn_t s5p_aes_interrupt(int irq, void *dev_id) > if (err_dma_hx == 1) > s5p_set_dma_hashdata(dev, dev->hash_sg_iter); > > + req = dev->req; Please put it before new line (so there will be new line before unlock). Logically it should not be separated from other commands in error path. Best regards, Krzysztof