AZL-106095

In the Linux kernel, the following vulnerability has been resolved:

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.