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/process/maintainer-devicetree.rst | 72 +++++++++++++++++++++++++ 1 file changed, 72 insertions(+) create mode 100644 Documentation/process/maintainer-devicetree.rst (limited to 'Documentation/process/maintainer-devicetree.rst') diff --git a/Documentation/process/maintainer-devicetree.rst b/Documentation/process/maintainer-devicetree.rst new file mode 100644 index 000000000..ecc3ed638 --- /dev/null +++ b/Documentation/process/maintainer-devicetree.rst @@ -0,0 +1,72 @@ +.. SPDX-License-Identifier: GPL-2.0 + +====================================== +Devicetree and Open Firmware Subsystem +====================================== + +Other Process Documents +----------------------- + +Please see the documents in Documentation/devicetree/bindings/ for information +on how to write proper Devicetree bindings and how to submit patches. + +Patch Review and Handling +------------------------- + +Patches handled by Devicetree maintainers are processed differently depending +on the patch type: + +1. Core OF driver code, e.g. drivers/of/: + patches are reviewed and applied by DT maintainers. + +2. Devicetree bindings: + patches are reviewed by DT maintainers, but should be applied by subsystem + maintainers except in certain cases. See also *For kernel maintainers* in + Documentation/devicetree/bindings/submitting-patches.rst. + +3. DTS and drivers: + DT maintainers might provide comments, but review is generally not expected. + DTS must pass schema checks (dtbs_check) or at least do not add any + new warnings. + +Patchwork +~~~~~~~~~ + +Devicetree maintainers review patches using Patchwork, so the current status of +a patch can be checked there. For typical driver submissions, Patchwork +receives the entire patch set, but only a few patches are usually Devicetree +bindings that are reviewed by DT maintainers. + +Explanation of Patchwork statuses: + + - **New**: Not yet processed by the automation toolset. + - **Needs ACK**: Waiting for review by DT maintainers. + - **Handled Elsewhere**: Non-DT patch; not being reviewed here. + - **RFC**: Patch was likely ignored because it was an incomplete RFC. + - **Changes Requested**: Patch was reviewed and DT maintainers expect changes. + - **Accepted**: Patch was reviewed and applied by DT maintainers to their tree. + - **Not Applicable**: Patch was reviewed and is likely in good shape, with a + *Reviewed-by* or *Acked-by* tag provided, but DT maintainers expect someone + else to apply it. + +Patch Re-review and Pinging +~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +Due to the high volume of email traffic, Devicetree maintainers do not read +every email they receive and instead rely on Patchwork during the review +process. They also often skip patches that have already been reviewed. + +As a result, maintainers might miss: + +1. Questions about already reviewed patches. +2. Pings, for example when a patch has been reviewed by DT maintainers but has + not been picked up by subsystem maintainers. + +Such cases can be addressed by: + +1. Pinging DT maintainers on the IRC channel. +2. Dropping the DT maintainer’s *Acked-by* or *Reviewed-by* tag when sending a new + version of the patch set, together with an explanation in the patch + changelog describing why the tag was removed and what is expected from DT + maintainers. + -- cgit v1.3.1