CVE-2025-39784

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> PCI: Fix link speed calculation on retrain failure<br /> <br /> When pcie_failed_link_retrain() fails to retrain, it tries to revert to the<br /> previous link speed. However it calculates that speed from the Link<br /> Control 2 register without masking out non-speed bits first.<br /> <br /> PCIE_LNKCTL2_TLS2SPEED() converts such incorrect values to<br /> PCI_SPEED_UNKNOWN (0xff), which in turn causes a WARN splat in<br /> pcie_set_target_speed():<br /> <br /> pci 0000:00:01.1: [1022:14ed] type 01 class 0x060400 PCIe Root Port<br /> pci 0000:00:01.1: broken device, retraining non-functional downstream link at 2.5GT/s<br /> pci 0000:00:01.1: retraining failed<br /> WARNING: CPU: 1 PID: 1 at drivers/pci/pcie/bwctrl.c:168 pcie_set_target_speed<br /> RDX: 0000000000000001 RSI: 00000000000000ff RDI: ffff9acd82efa000<br /> pcie_failed_link_retrain<br /> pci_device_add<br /> pci_scan_single_device<br /> <br /> Mask out the non-speed bits in PCIE_LNKCTL2_TLS2SPEED() and<br /> PCIE_LNKCAP_SLS2SPEED() so they don&amp;#39;t incorrectly return PCI_SPEED_UNKNOWN.<br /> <br /> [bhelgaas: commit log, add details from https://lore.kernel.org/r/1c92ef6bcb314ee6977839b46b393282e4f52e74.1750684771.git.lukas@wunner.de]