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/sysfs-block-loop | 50 ++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 Documentation/ABI/testing/sysfs-block-loop (limited to 'Documentation/ABI/testing/sysfs-block-loop') diff --git a/Documentation/ABI/testing/sysfs-block-loop b/Documentation/ABI/testing/sysfs-block-loop new file mode 100644 index 000000000..627f4eb87 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-block-loop @@ -0,0 +1,50 @@ +What: /sys/block/loopX/loop/autoclear +Date: Aug, 2010 +KernelVersion: v2.6.37 +Contact: linux-block@vger.kernel.org +Description: + (RO) Shows if the device is in autoclear mode or not ( "1" or + "0"). Autoclear (if set) indicates that the loopback device will + self-distruct after last close. + +What: /sys/block/loopX/loop/backing_file +Date: Aug, 2010 +KernelVersion: v2.6.37 +Contact: linux-block@vger.kernel.org +Description: + (RO) The path of the backing file that the loop device maps its + data blocks to. + +What: /sys/block/loopX/loop/offset +Date: Aug, 2010 +KernelVersion: v2.6.37 +Contact: linux-block@vger.kernel.org +Description: + (RO) Start offset (in bytes). + +What: /sys/block/loopX/loop/sizelimit +Date: Aug, 2010 +KernelVersion: v2.6.37 +Contact: linux-block@vger.kernel.org +Description: + (RO) The size (in bytes) that the block device maps, starting + from the offset. + +What: /sys/block/loopX/loop/partscan +Date: Aug, 2011 +KernelVersion: v3.10 +Contact: linux-block@vger.kernel.org +Description: + (RO) Shows if automatic partition scanning is enabled for the + device or not ("1" or "0"). This can be requested individually + per loop device during its setup by setting LO_FLAGS_PARTSCAN in + in the ioctl request. By default, no partition tables are + scanned. + +What: /sys/block/loopX/loop/dio +Date: Aug, 2015 +KernelVersion: v4.10 +Contact: linux-block@vger.kernel.org +Description: + (RO) Shows if direct IO is being used to access backing file or + not ("1 or "0"). -- cgit v1.3.1