CVE-2026-93168

/// Technical description

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

dmaengine: xilinx_dma: Fix CPU stall in xilinx_dma_poll_timeout

Currently when calling xilinx_dma_poll_timeout with delay_us=0 and a

condition that is never fulfilled, the CPU busy-waits for prolonged time

and the timeout triggers only with a massive delay causing a CPU stall.

This happens due to a huge underestimation of wall clock time in

poll_timeout_us_atomic. Commit 7349a69cf312 ("iopoll: Do not use

timekeeping in read_poll_timeout_atomic()") changed the behavior to no

longer use ktime_get at the expense of underestimation of wall clock

time which appears to be very large for delay_us=0. Instead of timing

out after approximately XILINX_DMA_LOOP_COUNT microseconds, the timeout

takes XILINX_DMA_LOOP_COUNT * 1000 * (time that the overhead of the for

loop in poll_timeout_us_atomic takes) which is in the range of several

minutes for XILINX_DMA_LOOP_COUNT=1000000. Fix this by using a non-zero

value for delay_us. Use

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References