Live › vulnerability › CVE-2026-99188
Go to dashboardIn the Linux kernel's stmmac Ethernet driver for dwmac1000, a pending RGMII status bit is never cleared after a link change, so the MAC interrupt fires repeatedly. On resume from suspend this can starve the CPU and cause a soft lockup, watchdog reset or hang.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-28 11:32 UTC. All times on this page are UTC.
Systems running a Linux kernel with the stmmac driver on a dwmac1000 MAC using RGMII, particularly boards that resume from s2idle with wake-on-LAN and where the resume thread shares a CPU with the MAC interrupt. Sources report examples on Helios64 (dwmac-rk) and ODROID-HC4 (dwmac-meson8b). Systems without these MACs or without this resume pattern are unlikely to be affected.
No product ranges from the sources yet.
dwmac_dma_interrupt: unexpected status 04000000 after resume.Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
In the Linux kernel, the following vulnerability has been resolved:
net: stmmac: dwmac1000: clear the RGMII status interrupt
Since commit 2e2c878a3141 ("net: stmmac: remove SGMII/RGMII/SMII interrupt handling") nothing on the RGMII path reads GMAC_RGSMIIIS, so RGSMIIIS stays pending behind GMAC_INT_MASK from the first link change on. stmmac_resume() resets the MAC in stmmac_hw_setup(); the reset sets GMAC_INT_MASK to 0 until dwmac1000_core_init() writes the mask again, and the pending status storms the line:
dwmac_dma_interrupt: unexpected status 04000000
A register dump at the first message on ODROID-HC4 showed it:
core int_status 00000001 int_mask 00000000 pmt 00000000 rgsmiiis 0000000d
When the resume thread runs on the CPU that takes the MAC interrupt, the storm starves it: a soft lockup, then a watchdog reset or a hang.
Read GMAC_RGSMIIIS in dwmac1000_irq_status() when the status is not masked, as the driver did before 2e2c878a3141; the read clears it.
Wake-on-LAN resume from s2idle with the resume thread and the MAC interrupt on one CPU: Helios64 (dwmac-rk), 7.3-rc6, soft-locked in 3 of 3 resumes without a fix and in 0 of 10 with this patch; it ran with an out-of-tree dwmac-rk change that keeps the GMAC powered across suspend. ODROID-HC4 (dwmac-meson8b): 0 of 10 with this patch, 2 of 2 without a fix on a 7.3-rc5 build. irq_rgmii_n went up by one per resume.
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