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-olpc | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) create mode 100644 Documentation/ABI/testing/debugfs-olpc (limited to 'Documentation/ABI/testing/debugfs-olpc') diff --git a/Documentation/ABI/testing/debugfs-olpc b/Documentation/ABI/testing/debugfs-olpc new file mode 100644 index 000000000..bd76cc6d5 --- /dev/null +++ b/Documentation/ABI/testing/debugfs-olpc @@ -0,0 +1,16 @@ +What: /sys/kernel/debug/olpc-ec/cmd +Date: Dec 2011 +KernelVersion: 3.4 +Contact: devel@lists.laptop.org +Description: + +A generic interface for executing OLPC Embedded Controller commands and +reading their responses. + +To execute a command, write data with the format: CC:N A A A A +CC is the (hex) command, N is the count of expected reply bytes, and A A A A +are optional (hex) arguments. + +To read the response (if any), read from the generic node after executing +a command. Hex reply bytes will be returned, *whether or not* they came from +the immediately previous command. -- cgit v1.3.1