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16:58:10 -0400 From: Frank Li To: Hongling Zeng Cc: vkoul@kernel.org, Frank.Li@kernel.org, wens@kernel.org, jernej.skrabec@gmail.com, samuel@sholland.org, mripard@kernel.org, arnd@arndb.de, dmaengine@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org, zhongling0719@126.com Subject: Re: [PATCH RESEND v5] dmaengine: sun6i-dma: Fix use-after-free in error handling paths Message-ID: References: <20260727061142.44195-1-zenghongling@kylinos.cn> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260727061142.44195-1-zenghongling@kylinos.cn> X-ClientProxiedBy: PH8P221CA0029.NAMP221.PROD.OUTLOOK.COM (2603:10b6:510:2d8::34) To GV2PR04MB11799.eurprd04.prod.outlook.com (2603:10a6:150:2cf::9) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: GV2PR04MB11799:EE_|PAWPR04MB9936:EE_ X-MS-Office365-Filtering-Correlation-Id: 37710516-81e8-4bea-e684-08defa46c463 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X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: uMlbLV6yJXglVHyUrVf/aVDEps4E4q2XTWOFYnYB28lf09iZOFLZPWaMY5oje873bW8U5ROXUoOAKwLwjG/Tvsud8K9/RoC9nnY2XTS2g0GoAk5uFOairCnHFA9uY3mj X-MS-Exchange-Transport-CrossTenantHeadersStamped: PAWPR04MB9936 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260814_135825_693704_A90B1B59 X-CRM114-Status: GOOD ( 23.79 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jul 27, 2026 at 02:11:42PM +0800, Hongling Zeng wrote: > In error handling paths, the for loop frees v_lli in the loop body, > then accesses v_lli->v_lli_next and v_lli->p_lli_next in the > increment expression, which is use-after-free. > > Fix by refactoring the cleanup into a helper function sun6i_dma_free_desc() > that saves both the next virtual and physical pointers before freeing the > current node, preventing the use-after-free. > > Fixes: 555859308723 ("dmaengine: Add driver for Allwinner sun6i DMA") > Signed-off-by: Hongling Zeng > Suggested-by: Jernej Skrabec > Reviewed-by: Jernej Skrabec Reviewed-by: Frank Li > > --- > Changes in v2: > -Refactored the fix to avoid code duplication by creating a helper function > sun6i_dma_free_lli_list() that handles LLI list cleanup > -Add Suggested-by: Jernej Skrabec > --- > Change in v3: > -Further refactoring to move txd handling into the helper function > as suggested by Jernej > --- > Change in v4: > -Add reviewed-by > --- > Change in v5: > -Correct the commit message. > --- > drivers/dma/sun6i-dma.c | 31 ++++++++++++++++--------------- > 1 file changed, 16 insertions(+), 15 deletions(-) > > diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c > index fcc88a74d821..e161fc298b86 100644 > --- a/drivers/dma/sun6i-dma.c > +++ b/drivers/dma/sun6i-dma.c > @@ -406,16 +406,12 @@ static inline void sun6i_dma_dump_lli(struct sun6i_vchan *vchan, > v_lli->len, v_lli->para, v_lli->p_lli_next); > } > > -static void sun6i_dma_free_desc(struct virt_dma_desc *vd) > +static void sun6i_dma_free_desc(struct sun6i_dma_dev *sdev, > + struct sun6i_desc *txd) > { > - struct sun6i_desc *txd = to_sun6i_desc(&vd->tx); > - struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vd->tx.chan->device); > struct sun6i_dma_lli *v_lli, *v_next; > dma_addr_t p_lli, p_next; > > - if (unlikely(!txd)) > - return; > - > p_lli = txd->p_lli; > v_lli = txd->v_lli; > > @@ -432,6 +428,17 @@ static void sun6i_dma_free_desc(struct virt_dma_desc *vd) > kfree(txd); > } > > +static void sun6i_dma_free_desc_virt(struct virt_dma_desc *vd) > +{ > + struct sun6i_desc *txd = to_sun6i_desc(&vd->tx); > + struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vd->tx.chan->device); > + > + if (unlikely(!txd)) > + return; > + > + sun6i_dma_free_desc(sdev, txd); > +} > + > static int sun6i_dma_start_desc(struct sun6i_vchan *vchan) > { > struct sun6i_dma_dev *sdev = to_sun6i_dma_dev(vchan->vc.chan.device); > @@ -788,10 +795,7 @@ static struct dma_async_tx_descriptor *sun6i_dma_prep_slave_sg( > return vchan_tx_prep(&vchan->vc, &txd->vd, flags); > > err_lli_free: > - for (p_lli = txd->p_lli, v_lli = txd->v_lli; v_lli; > - p_lli = v_lli->p_lli_next, v_lli = v_lli->v_lli_next) > - dma_pool_free(sdev->pool, v_lli, p_lli); > - kfree(txd); > + sun6i_dma_free_desc(sdev, txd); > return NULL; > } > > @@ -869,10 +873,7 @@ static struct dma_async_tx_descriptor *sun6i_dma_prep_dma_cyclic( > return vchan_tx_prep(&vchan->vc, &txd->vd, flags); > > err_lli_free: > - for (p_lli = txd->p_lli, v_lli = txd->v_lli; v_lli; > - p_lli = v_lli->p_lli_next, v_lli = v_lli->v_lli_next) > - dma_pool_free(sdev->pool, v_lli, p_lli); > - kfree(txd); > + sun6i_dma_free_desc(sdev, txd); > return NULL; > } > > @@ -1432,7 +1433,7 @@ static int sun6i_dma_probe(struct platform_device *pdev) > struct sun6i_vchan *vchan = &sdc->vchans[i]; > > INIT_LIST_HEAD(&vchan->node); > - vchan->vc.desc_free = sun6i_dma_free_desc; > + vchan->vc.desc_free = sun6i_dma_free_desc_virt; > vchan_init(&vchan->vc, &sdc->slave); > } > > -- > 2.25.1 >