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 --- Documentation/dev-tools/testing-devices.rst | 47 +++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) create mode 100644 Documentation/dev-tools/testing-devices.rst (limited to 'Documentation/dev-tools/testing-devices.rst') diff --git a/Documentation/dev-tools/testing-devices.rst b/Documentation/dev-tools/testing-devices.rst new file mode 100644 index 000000000..ab26adb99 --- /dev/null +++ b/Documentation/dev-tools/testing-devices.rst @@ -0,0 +1,47 @@ +.. SPDX-License-Identifier: GPL-2.0 +.. Copyright (c) 2024 Collabora Ltd + +============================= +Device testing with kselftest +============================= + + +There are a few different kselftests available for testing devices generically, +with some overlap in coverage and different requirements. This document aims to +give an overview of each one. + +Note: Paths in this document are relative to the kselftest folder +(``tools/testing/selftests``). + +Device oriented kselftests: + +* Devicetree (``dt``) + + * **Coverage**: Probe status for devices described in Devicetree + * **Requirements**: None + +* Error logs (``devices/error_logs``) + + * **Coverage**: Error (or more critical) log messages presence coming from any + device + * **Requirements**: None + +* Discoverable bus (``devices/probe``) + + * **Coverage**: Presence and probe status of USB or PCI devices that have been + described in the reference file + * **Requirements**: Manually describe the devices that should be tested in a + YAML reference file (see ``devices/probe/boards/google,spherion.yaml`` for + an example) + +* Exist (``devices/exist``) + + * **Coverage**: Presence of all devices + * **Requirements**: Generate the reference (see ``devices/exist/README.rst`` + for details) on a known-good kernel + +Therefore, the suggestion is to enable the error log and devicetree tests on all +(DT-based) platforms, since they don't have any requirements. Then to greatly +improve coverage, generate the reference for each platform and enable the exist +test. The discoverable bus test can be used to verify the probe status of +specific USB or PCI devices, but is probably not worth it for most cases. -- cgit v1.3.1