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net: stmmac: xgmac2: disable RBUE in default RX interrupt mask

Type: advisorySource: OSV1 source record

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: xgmac2: disable RBUE in default RX interrupt mask Enabling the RX Buffer Unavailable (RBUE) interrupt is counterproductive and can trigger a MAC interrupt storm under heavy RX pressure. When the DMA runs out of RX descriptors it fires RBUE continuously until software refills the ring. However, RBUE is redundant: the normal RX completion interrupt (RIE) already triggers NAPI, which processes completed descriptors and refills the ring, causing the DMA to resume. The RBUE handler itself only sets handle_rx - the same outcome as RIE. On Agilex5 under heavy RX pressure, the MAC interrupt (which includes RBUE) was observed firing 1,821,811,555 times against only 2,618,627 actual RX completions - a ~695x ratio - confirming the severity of the storm. RBUE does not provide OOM recovery. If page_pool is exhausted, stmmac_rx_refill() cannot advance the DMA tail pointer, the DMA stays suspended, and RBUE fires again on the next NAPI completion - a storm with no forward progress. This patch trades that storm for a clean stall with the same RX outcome. Proper OOM recovery is a pre-existing gap outside the scope of this fix. Note: as a consequence of disabling RBUE, the rx_buf_unav_irq ethtool counter will always read 0 on XGMAC2 devices. This behaviour is already inconsistent across DWMAC core versions. Remove RBUE from XGMAC_DMA_INT_DEFAULT_EN and XGMAC_DMA_INT_DEFAULT_RX to prevent the interrupt storm while

Announced Source revision 1
Original source ↗

CVE-2026-93830

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: osv:CVE-2026-93830

Kernel

Source reference: /affected/1/package/name

Affected versions
Not stated in this record
Fixed versions
5.10.271

Source reference: /affected/1/ranges

5.15.222

Source reference: /affected/1/ranges

6.1.189

Source reference: /affected/1/ranges

6.6.158

Source reference: /affected/1/ranges

6.12.111

Source reference: /affected/1/ranges

6.18.53

Source reference: /affected/1/ranges

Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

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            "fixed": "7a10e54e42a8f73a8d731f5a281fc06bb41b9250"
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]
Related CVEs
CVE-2026-93830

Source reference: /id

Publisher severity

high

Source reference: /severity/0/score

Linked CVE context

These ratings describe the referenced vulnerabilities and products. They are not a severity rating for every application using this dependency.

CVE-2026-93830 · High

Linux, Linux

Event
#83542 · Revision 1
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Publisher date
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