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Thu, 17 Sep 2020 16:04:02 +0000 Received: from abhmp0017.oracle.com (abhmp0017.oracle.com [141.146.116.23]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 08HG3rBG001943; Thu, 17 Sep 2020 16:03:53 GMT Received: from char.us.oracle.com (/10.152.32.25) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 17 Sep 2020 16:03:52 +0000 Received: by char.us.oracle.com (Postfix, from userid 1000) id E82FB6A013C; Thu, 17 Sep 2020 12:05:17 -0400 (EDT) Date: Thu, 17 Sep 2020 12:05:17 -0400 From: Konrad Rzeszutek Wilk To: Thomas Tai Subject: Re: [PATCH V2] dma-direct: Fix potential NULL pointer dereference Message-ID: <20200917160517.GB10122@char.us.oracle.com> References: <1600289466-23805-1-git-send-email-thomas.tai@oracle.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1600289466-23805-1-git-send-email-thomas.tai@oracle.com> User-Agent: Mutt/1.9.1 (2017-09-22) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9747 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 spamscore=0 adultscore=0 suspectscore=0 phishscore=0 malwarescore=0 bulkscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009170120 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9747 signatures=668679 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 phishscore=0 impostorscore=0 priorityscore=1501 malwarescore=0 suspectscore=0 mlxlogscore=999 clxscore=1015 adultscore=0 lowpriorityscore=0 spamscore=0 mlxscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009170120 Cc: linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, robin.murphy@arm.com, hch@lst.de X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Wed, Sep 16, 2020 at 02:51:06PM -0600, Thomas Tai wrote: > When booting the kernel v5.9-rc4 on a VM, the kernel would panic when > printing a warning message in swiotlb_map(). The dev->dma_mask must not > be a NULL pointer when calling the dma mapping layer. A NULL pointer check > can potentially avoid the panic. > > [drm] Initialized virtio_gpu 0.1.0 0 for virtio0 on minor 0 > BUG: kernel NULL pointer dereference, address: 0000000000000000 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 0 P4D 0 > Oops: 0000 [#1] SMP PTI > CPU: 1 PID: 331 Comm: systemd-udevd Not tainted 5.9.0-rc4 #1 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), > BIOS 1.13.0-1ubuntu1 04/01/2014 > RIP: 0010:swiotlb_map+0x1ac/0x200 > Code: e8 d9 fc ff ff 80 3d 92 ee 4c 01 00 75 51 49 8b 84 24 48 02 00 00 > 4d 8b 6c 24 50 c6 05 7c ee 4c 01 01 4d 8b bc 24 58 02 00 00 <4c> 8b 30 > 4d 85 ed 75 04 4d 8b 2c 24 4c 89 e7 e8 10 6b 4f 00 4d 89 > RSP: 0018:ffff9f96801af6f8 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: 0000000000001000 RCX: 0000000000000080 > RDX: 000000000000007f RSI: 0000000000000202 RDI: 0000000000000202 > RBP: ffff9f96801af748 R08: ffffffffffffffff R09: 0000000000000020 > R10: 0000000000000000 R11: ffff8fabfffa3000 R12: ffff8faad02c7810 > R13: 0000000000000000 R14: 0000000000000020 R15: 0000000000000000 > FS: 00007fabc63588c0(0000) GS:ffff8fabf7c80000(0000) > knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000000 CR3: 0000000151496005 CR4: 0000000000370ee0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > dma_direct_map_sg+0x124/0x210 > dma_map_sg_attrs+0x32/0x50 > drm_gem_shmem_get_pages_sgt+0x6a/0x90 [drm] > virtio_gpu_object_create+0x140/0x2f0 [virtio_gpu] > ? ww_mutex_unlock+0x26/0x30 > virtio_gpu_mode_dumb_create+0xab/0x160 [virtio_gpu] > drm_mode_create_dumb+0x82/0x90 [drm] > drm_client_framebuffer_create+0xaa/0x200 [drm] > drm_fb_helper_generic_probe+0x59/0x150 [drm_kms_helper] > drm_fb_helper_single_fb_probe+0x29e/0x3e0 [drm_kms_helper] > __drm_fb_helper_initial_config_and_unlock+0x41/0xd0 [drm_kms_helper] > drm_fbdev_client_hotplug+0xe6/0x1a0 [drm_kms_helper] > drm_fbdev_generic_setup+0xaf/0x170 [drm_kms_helper] > virtio_gpu_probe+0xea/0x100 [virtio_gpu] > virtio_dev_probe+0x14b/0x1e0 [virtio] > really_probe+0x1db/0x440 > driver_probe_device+0xe9/0x160 > device_driver_attach+0x5d/0x70 > __driver_attach+0x8f/0x150 > ? device_driver_attach+0x70/0x70 > bus_for_each_dev+0x7e/0xc0 > driver_attach+0x1e/0x20 > bus_add_driver+0x152/0x1f0 > driver_register+0x74/0xd0 > ? 0xffffffffc0529000 > register_virtio_driver+0x20/0x30 [virtio] > virtio_gpu_driver_init+0x15/0x1000 [virtio_gpu] > do_one_initcall+0x4a/0x1fa > ? _cond_resched+0x19/0x30 > ? kmem_cache_alloc_trace+0x16b/0x2e0 > do_init_module+0x62/0x240 > load_module+0xe0e/0x1100 > ? security_kernel_post_read_file+0x5c/0x70 > __do_sys_finit_module+0xbe/0x120 > ? __do_sys_finit_module+0xbe/0x120 > __x64_sys_finit_module+0x1a/0x20 > do_syscall_64+0x38/0x50 > entry_SYSCALL_64_after_hwframe+0x44/0xa9 > > Signed-off-by: Thomas Tai Reviewed-by: Konrad Rzeszutek Wilk Thank you! > --- > include/linux/dma-direct.h | 3 --- > kernel/dma/mapping.c | 11 +++++++++++ > 2 files changed, 11 insertions(+), 3 deletions(-) > > diff --git a/include/linux/dma-direct.h b/include/linux/dma-direct.h > index 6e87225..0648708 100644 > --- a/include/linux/dma-direct.h > +++ b/include/linux/dma-direct.h > @@ -62,9 +62,6 @@ static inline bool dma_capable(struct device *dev, dma_addr_t addr, size_t size, > { > dma_addr_t end = addr + size - 1; > > - if (!dev->dma_mask) > - return false; > - > if (is_ram && !IS_ENABLED(CONFIG_ARCH_DMA_ADDR_T_64BIT) && > min(addr, end) < phys_to_dma(dev, PFN_PHYS(min_low_pfn))) > return false; > diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c > index 0d12942..7133d5c 100644 > --- a/kernel/dma/mapping.c > +++ b/kernel/dma/mapping.c > @@ -144,6 +144,10 @@ dma_addr_t dma_map_page_attrs(struct device *dev, struct page *page, > dma_addr_t addr; > > BUG_ON(!valid_dma_direction(dir)); > + > + if (WARN_ON_ONCE(!dev->dma_mask)) > + return DMA_MAPPING_ERROR; > + > if (dma_map_direct(dev, ops)) > addr = dma_direct_map_page(dev, page, offset, size, dir, attrs); > else > @@ -179,6 +183,10 @@ int dma_map_sg_attrs(struct device *dev, struct scatterlist *sg, int nents, > int ents; > > BUG_ON(!valid_dma_direction(dir)); > + > + if (WARN_ON_ONCE(!dev->dma_mask)) > + return 0; > + > if (dma_map_direct(dev, ops)) > ents = dma_direct_map_sg(dev, sg, nents, dir, attrs); > else > @@ -213,6 +221,9 @@ dma_addr_t dma_map_resource(struct device *dev, phys_addr_t phys_addr, > > BUG_ON(!valid_dma_direction(dir)); > > + if (WARN_ON_ONCE(!dev->dma_mask)) > + return DMA_MAPPING_ERROR; > + > /* Don't allow RAM to be mapped */ > if (WARN_ON_ONCE(pfn_valid(PHYS_PFN(phys_addr)))) > return DMA_MAPPING_ERROR; > -- > 1.8.3.1 > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu