Executive brief
A vulnerability in the Linux kernel's networking subsystem can cause a system deadlock when certain network hardware (SFP cages) is used with generic drivers. This issue occurs during the hardware initialization process, potentially causing the system to become unresponsive. This affects the availability of the system but does not directly expose data.
Technical details
A deadlock condition exists in the Linux kernel's `drivers/net/phy/phy_device.c` component. The root cause is that generic PHY (genphy) drivers perform probing under the RTNL (Routing Netlink) lock, whereas non-generic drivers do not. When `phy_sfp_probe()` is called for a genphy-driven device, it triggers `sfp_bus_add_upstream()`, which attempts to acquire the same RTNL lock, resulting in a kernel deadlock. The fix involves skipping the SFP probe path when `is_genphy_driven` is true. This issue was introduced in a previous commit that moved the SFP probing logic into a shared path.
Affected products
- Linux Linux 7.0, 7.0.13, 7.1
Timeline
- 2026-06-04: patched: Initial fix commit authored
- 2026-06-25: disclosed: CVE published