CVE-2024-43876 PCI: rcar: Demote WARN() to dev_warn_ratelimited() in rcar_pcie_wakeup()

What is CVE-2024-43876?

CVE-2024-43876 is a medium-severity denial of service vulnerability in Linux kernel, published on 21 Aug 2024. It can only be exploited from the same machine or local network, with no action from the victim.

Official description

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

PCI: rcar: Demote WARN() to dev_warn_ratelimited() in rcar_pcie_wakeup()

Avoid large backtrace, it is sufficient to warn the user that there has been a link problem. Either the link has failed and the system is in need of maintenance, or the link continues to work and user has been informed. The message from the warning can be looked up in the sources.

This makes an actual link issue less verbose.

First of all, this controller has a limitation in that the controller driver has to assist the hardware with transition to L1 link state by writing L1IATN to PMCTRL register, the L1 and L0 link state switching is not fully automatic on this controller.

In case of an ASMedia ASM1062 PCIe SATA controller which does not support ASPM, on entry to suspend or during platform pm_test, the SATA controller enters D3hot state and the link enters L1 state. If the SATA controller wakes up before rcar_pcie_wakeup() was called and returns to D0, the link returns to L0 before the controller driver even started its transition to L1 link state. At this point, the SATA controller did send an PM_ENTER_L1 DLLP to the PCIe controller and the PCIe controller received it, and the PCIe controller did set PMSR PMEL1RX bit.

Once rcar_pcie_wakeup() is called, if the link is already back in L0 state and PMEL1RX bit is set, the controller driver has no way to determine if it should perform the link transition to L1 state, or treat the link as if it is in L0 state. Currently the driver attempts to perform the transition to L1 link state unconditionally, which in this specific case fails with a PMSR L1FAEG poll timeout, however the link still works as it is already back in L0 state.

Reduce this warning verbosity. In case the link is really broken, the rcar_pcie_config_access() would fail, otherwise it will succeed and any system with this controller and ASM1062 can suspend without generating a backtrace.

Which versions are affected by CVE-2024-43876?

It affects 1 product.

Products include Linux kernel.

How do I fix CVE-2024-43876?

Apply the vendor's patch.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2024-43876 being exploited?

There is no known exploitation of CVE-2024-43876 in the wild and no public exploit code.

Other vulnerabilities in Linux kernel

• CVE-2026-53266 Linux Kernel Out-of-Bounds Write Exploited High 8.8
• CVE-2013-6282 Linux Kernel Improper Input Validation Exploited High 8.8
• CVE-2022-0185 Linux Kernel Heap-Based Buffer Overflow Exploited High 8.4
• CVE-2013-2094 Linux Kernel Privilege Escalation Exploited High 8.4
• CVE-2026-53362 Linux Kernel Unspecified Exploited High 7.8

All Linux kernel vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as BELL-CVE-2024-43876, DEBIAN-CVE-2024-43876, GHSA-88v6-4cm5-82pp, UBUNTU-CVE-2024-43876.