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/ABI/testing/debugfs-ec | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) create mode 100644 Documentation/ABI/testing/debugfs-ec (limited to 'Documentation/ABI/testing/debugfs-ec') diff --git a/Documentation/ABI/testing/debugfs-ec b/Documentation/ABI/testing/debugfs-ec new file mode 100644 index 000000000..ab6099daa --- /dev/null +++ b/Documentation/ABI/testing/debugfs-ec @@ -0,0 +1,21 @@ +What: /sys/kernel/debug/ec/*/{gpe,use_global_lock,io} +Date: July 2010 +Contact: Thomas Renninger +Description: + +General information like which GPE is assigned to the EC and whether +the global lock should get used. +Knowing the EC GPE one can watch the amount of HW events related to +the EC here (XY -> GPE number from `/sys/kernel/debug/ec/*/gpe`): +/sys/firmware/acpi/interrupts/gpeXY + +The io file is binary and a userspace tool located here: +ftp://ftp.suse.com/pub/people/trenn/sources/ec/ +should get used to read out the 256 Embedded Controller registers +or writing to them. + +CAUTION: + Do not write to the Embedded Controller if you don't know + what you are doing! Rebooting afterwards also is a good idea. + This can influence the way your machine is cooled and fans may + not get switched on again after you did a wrong write. -- cgit v1.3.1