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/driver-api/devfreq.rst | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 Documentation/driver-api/devfreq.rst (limited to 'Documentation/driver-api/devfreq.rst') diff --git a/Documentation/driver-api/devfreq.rst b/Documentation/driver-api/devfreq.rst new file mode 100644 index 000000000..4a0bf87a3 --- /dev/null +++ b/Documentation/driver-api/devfreq.rst @@ -0,0 +1,30 @@ +.. SPDX-License-Identifier: GPL-2.0 + +======================== +Device Frequency Scaling +======================== + +Introduction +------------ + +This framework provides a standard kernel interface for Dynamic Voltage and +Frequency Switching on arbitrary devices. + +It exposes controls for adjusting frequency through sysfs files which are +similar to the cpufreq subsystem. + +Devices for which current usage can be measured can have their frequency +automatically adjusted by governors. + +API +--- + +Device drivers need to initialize a :c:type:`devfreq_profile` and call the +:c:func:`devfreq_add_device` function to create a :c:type:`devfreq` instance. + +.. kernel-doc:: include/linux/devfreq.h +.. kernel-doc:: include/linux/devfreq-event.h +.. kernel-doc:: drivers/devfreq/devfreq.c + :export: +.. kernel-doc:: drivers/devfreq/devfreq-event.c + :export: -- cgit v1.3.1