dmaengine: mmp_pdma: Fix race condition in mmp_pdma_residue()

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: dmaengine: mmp_pdma: Fix race condition in mmp_pdma_residue() Add proper locking in mmp_pdma_residue() to prevent use-after-free when accessing descriptor list and descriptor contents. The race occurs when multiple threads call tx_status() while the tasklet on another CPU is freeing completed descriptors: CPU 0 CPU 1 ----- ----- mmp_pdma_tx_status() mmp_pdma_residue() -> NO LOCK held list_for_each_entry(sw, ..) DMA interrupt dma_do_tasklet() -> spin_lock(&desc_lock) list_move(sw->node, ...) spin_unlock(&desc_lock) | dma_pool_free(sw) <- FREED! -> access sw->desc <- UAF! This issue can be reproduced when running dmatest on the same channel with multiple threads (threads_per_chan > 1). Fix by protecting the chain_running list iteration and descriptor access with the chan->desc_lock spinlock.

References

• https://git.kernel.org/stable/c/3f0e0e2d9e752570041e95fd04635e2580097819
• https://git.kernel.org/stable/c/dfb5e05227745de43b7fd589721817a4337c970d
• https://git.kernel.org/stable/c/eba0c75670c022cb1f948600db972524bcfe8166
• https://git.kernel.org/stable/c/fc023b8fab057f0c910856ff36d3e12a30b7af4a
• https://git.kernel.org/stable/c/9f665b3c3d9a168410251f27a5d019b7bf93185c
• https://git.kernel.org/stable/c/a143545855bc2c6e1330f6f57ae375ac44af00a7