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/usb/functionfs-desc.rst | 39 +++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) create mode 100644 Documentation/usb/functionfs-desc.rst (limited to 'Documentation/usb/functionfs-desc.rst') diff --git a/Documentation/usb/functionfs-desc.rst b/Documentation/usb/functionfs-desc.rst new file mode 100644 index 000000000..39649774d --- /dev/null +++ b/Documentation/usb/functionfs-desc.rst @@ -0,0 +1,39 @@ +====================== +FunctionFS Descriptors +====================== + +Some of the descriptors that can be written to the FFS gadget are +described below. Device and configuration descriptors are handled +by the composite gadget and are not written by the user to the +FFS gadget. + +Descriptors are written to the "ep0" file in the FFS gadget +following the descriptor header. + +.. kernel-doc:: include/uapi/linux/usb/functionfs.h + :doc: descriptors + +Interface Descriptors +--------------------- + +Standard USB interface descriptors may be written. The class/subclass of the +most recent interface descriptor determines what type of class-specific +descriptors are accepted. + +Class-Specific Descriptors +-------------------------- + +Class-specific descriptors are accepted only for the class/subclass of the +most recent interface descriptor. The following are some of the +class-specific descriptors that are supported. + +DFU Functional Descriptor +~~~~~~~~~~~~~~~~~~~~~~~~~ + +When the interface class is USB_CLASS_APP_SPEC and the interface subclass +is USB_SUBCLASS_DFU, a DFU functional descriptor can be provided. +The DFU functional descriptor is a described in the USB specification for +Device Firmware Upgrade (DFU), version 1.1 as of this writing. + +.. kernel-doc:: include/uapi/linux/usb/functionfs.h + :doc: usb_dfu_functional_descriptor -- cgit v1.3.1