CVE-2026-93168 (GCVE-0-2026-93168)

Vulnerability from cvelistv5 – Published: 2026-09-17 16:11 – Updated: 2026-10-21 12:52
VLAI
Title
dmaengine: xilinx_dma: Fix CPU stall in xilinx_dma_poll_timeout
Summary
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 delay_us=10 to keep the delay in the hot path of starting DMA transfers minimal but still avoid CPU stalls in case of unexpected hardware failures. One-off measurement with delay_us=0 causes the cpu to busy wait around 7 minutes in the timeout case. After applying this patch with delay_us=10 the measured timeout was 1053428 microseconds which is roughly equivalent to the expected 1000000 microseconds specified in XILINX_DMA_LOOP_COUNT. Add a constant XILINX_DMA_POLL_DELAY_US for delay_us value.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 7033 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 9495f2648287029fb5545c34a0fa318426ebe84c , < 2ba67aa183a3ce174d534425b67eda84f6e3c896 (git)
Affected: 9495f2648287029fb5545c34a0fa318426ebe84c , < c30a26d4987a01e619449bf170f584c007e07d75 (git)
Affected: 9495f2648287029fb5545c34a0fa318426ebe84c , < f786e7b3adbf3bd14964a1cedf9d55b6ad91dcd7 (git)
Affected: 9495f2648287029fb5545c34a0fa318426ebe84c , < 8b5654d317277e6e505c23f8fa7e415237fefc7f (git)
Affected: 9495f2648287029fb5545c34a0fa318426ebe84c , < aa99c4d1d63bbc26a5fc4c667d89b2595743c19d (git)
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Linux Linux Affected: 4.6
Unaffected: 0 , < 4.6 (semver)
Unaffected: 6.6.160 , ≤ 6.6.* (semver)
Unaffected: 6.12.114 , ≤ 6.12.* (semver)
Unaffected: 6.18.57 , ≤ 6.18.* (semver)
Unaffected: 7.2.6 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
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      "cve": "CVE-2026-93168",
      "id": "CVE-2026-93168",
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}



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