From e873c74132f0c5f1452816cd9bb26208f0bba1e1 Mon Sep 17 00:00:00 2001 From: Shivank Garg Date: Sat, 22 Aug 2026 19:22:05 +0000 Subject: dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel() When dma_device_put() drops the last reference on chan->device->ref, dma_device_release() runs and may free the dma_device along with its channels. dma_chan_put() then still reads chan->device->owner via dma_chan_to_owner() for the trailing module_put(). KASAN catches it: slab-use-after-free in dma_chan_put+0x3e6/0x4c0 Read of size 8 by task insmod/6319 Freed by task 6319: kfree+0x225/0x470 dma_chan_put+0x395/0x4c0 dmaengine_put+0xf8/0x160 Cache the module owner in dma_chan_put() before the put so the trailing module_put() does not need chan->device. Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct") Suggested-by: Sashiko Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com Reviewed-by: Frank Li Reviewed-by: Logan Gunthorpe Signed-off-by: Shivank Garg Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com Signed-off-by: Vinod Koul --- samples/vfio-mdev/mdpy-defs.h | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) create mode 100644 samples/vfio-mdev/mdpy-defs.h (limited to 'samples/vfio-mdev/mdpy-defs.h') diff --git a/samples/vfio-mdev/mdpy-defs.h b/samples/vfio-mdev/mdpy-defs.h new file mode 100644 index 000000000..961c55ec3 --- /dev/null +++ b/samples/vfio-mdev/mdpy-defs.h @@ -0,0 +1,22 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Simple pci display device. + * + * Framebuffer memory is pci bar 0. + * Configuration (read-only) is in pci config space. + * Format field uses drm fourcc codes. + * ATM only DRM_FORMAT_XRGB8888 is supported. + */ + +/* pci ids */ +#define MDPY_PCI_VENDOR_ID PCI_VENDOR_ID_REDHAT +#define MDPY_PCI_DEVICE_ID 0x000f +#define MDPY_PCI_SUBVENDOR_ID PCI_SUBVENDOR_ID_REDHAT_QUMRANET +#define MDPY_PCI_SUBDEVICE_ID PCI_SUBDEVICE_ID_QEMU + +/* pci cfg space offsets for fb config (dword) */ +#define MDPY_VENDORCAP_OFFSET 0x40 +#define MDPY_VENDORCAP_SIZE 0x10 +#define MDPY_FORMAT_OFFSET (MDPY_VENDORCAP_OFFSET + 0x04) +#define MDPY_WIDTH_OFFSET (MDPY_VENDORCAP_OFFSET + 0x08) +#define MDPY_HEIGHT_OFFSET (MDPY_VENDORCAP_OFFSET + 0x0c) -- cgit v1.3.1