Executive brief
A logic error in the Linux kernel's Octeon EP virtual device adapter causes incorrect mapping between interrupt numbers and packet-processing rings. When interrupt numbers are non-contiguous or the first interrupt isn't the base address, the device mishandles ring notifications, potentially causing data loss or service disruption in virtualized networking environments.
Technical details
The vulnerability is a logic error in the interrupt handler (drivers/vdpa/octeon_ep/octep_vdpa_main.c). The handler incorrectly calculated ring indices by assuming IRQ numbers are contiguous and based on irqs[0], using the formula (irq - irqs[0]). This fails when IRQ numbers are non-contiguous or the base IRQ isn't at position 0, causing the handler to index into the wrong virtual queues. The fix replaces the arithmetic calculation with an explicit lookup in the irqs array, ensuring correct ring indexing regardless of IRQ numbering. Attack preconditions are minimal—any guest driver accessing the affected Octeon EP device will trigger the mishandling. The patch was committed in February 2026 and backported to stable kernels.
Affected products
- Linux Linux Kernel multiple versions affected; patch available
Timeline
- 2026-08-15: disclosed: CVE-2026-74309 published on NVD
- 2026-02-24: patched: Upstream fix commit 0d21a1d6375a05274291e32c1ab7cd57dbb69513
- 2026-07-24: patched: Backported to stable trees (commit 3ef0cfa77a3d526591be069850d186c255e3f0cc)