TrustedFirmware-M (aka Trusted Firmware for M profile Arm CPUs) before 2.1.3 and 2.2.x before 2.2.1 lacks length validation during a firmware upgrade. While processing a new image, the Firmware Upgrade (FWU) module does not validate the length field of the Type-Length-Value (TLV) structure for dependent components against the maximum allowed size. If the length specified in the TLV exceeds the size of the buffer allocated on the stack, the FWU module will overwrite the buffer (and potentially other stack data) with the TLV's value content. An attacker could exploit this by crafting a malicious TLV entry in the unprotected section of the MCUBoot upgrade image. By setting the length field to exceed the expected structure size, the attacker can manipulate the stack memory of the system during the upgrade process.

In the Linux kernel, the following vulnerability has been resolved: PCI: aardvark: Fix kernel panic during PIO transfer Trying to start a new PIO transfer by writing value 0 in PIO_START register when previous transfer has not yet completed (which is indicated by value 1 in PIO_START) causes an External Abort on CPU, which results in kernel panic: SError Interrupt on CPU0, code 0xbf000002 -- SError Kernel panic - not syncing: Asynchronous SError Interrupt To prevent kernel panic, it is required to reject a new PIO transfer when previous one has not finished yet. If previous PIO transfer is not finished yet, the kernel may issue a new PIO request only if the previous PIO transfer timed out. In the past the root cause of this issue was incorrectly identified (as it often happens during link retraining or after link down event) and special hack was implemented in Trusted Firmware to catch all SError events in EL3, to ignore errors with code 0xbf000002 and not forwarding any other errors to kernel and instead throw panic from EL3 Trusted Firmware handler. Links to discussion and patches about this issue: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/commit/?id=3c7dcdac5c50 https://lore.kernel.org/linux-pci/20190316161243.29517-1-repk@triplefau.lt/ https://lore.kernel.org/linux-pci/971be151d24312cc533989a64bd454b4@www.loen.fr/ https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/1541 But the real cause was the fact that during link retraining or after link down event the PIO transfer may take longer time, up to the 1.44s until it times out. This increased probability that a new PIO transfer would be issued by kernel while previous one has not finished yet. After applying this change into the kernel, it is possible to revert the mentioned TF-A hack and SError events do not have to be caught in TF-A EL3.