CVE-2025-39923

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

dmaengine: qcom: bam_dma: Fix DT error handling for num-channels/ees

When we don't have a clock specified in the device tree, we have no way to

ensure the BAM is on. This is often the case for remotely-controlled or

remotely-powered BAM instances. In this case, we need to read num-channels

from the DT to have all the necessary information to complete probing.

However, at the moment invalid device trees without clock and without

num-channels still continue probing, because the error handling is missing

return statements. The driver will then later try to read the number of

channels from the registers. This is unsafe, because it relies on boot

firmware and lucky timing to succeed. Unfortunately, the lack of proper

error handling here has been abused for several Qualcomm SoCs upstream,

causing early boot crashes in several situations [1, 2].

Avoid these early crashes by erroring out when any of the required DT

properties are missing. Note that this will break some of the existing DTs

upstream (mainly BAM instances related to the crypto engine). However,

clearly these DTs have never been tested properly, since the error in the

kernel log was just ignored. It's safer to disable the crypto engine for

these broken DTBs.

[1]: https://lore.kernel.org/r/[email protected]/

[2]: https://lore.kernel.org/r/[email protected]/