The Linux kernel NTB epf driver had a vulnerability where the interrupt service routine ntb_epf_vec_isr() called pci_irq_vector() from hardirq context. pci_irq_vector() internally calls msi_get_virq(), which acquires a mutex, causing a 'scheduling while atomic' kernel bug. This bug manifests as kernel crashes or instability due to improper locking in atomic context. The fix involves caching the Linux IRQ number during vector allocation and using this cached value in the ISR to avoid calling pci_irq_vector() in atomic context. Running the ISR in a threaded IRQ handler was considered but deemed unnecessary.

This vulnerability can cause kernel crashes or instability due to improper scheduling in atomic context, potentially leading to denial of service on affected systems. There is no indication of privilege escalation or code execution impact. No known exploits are reported in the wild.

A fix has been implemented in the Linux kernel to address this issue by caching the IRQ number and avoiding unsafe calls in the interrupt context. Users should update to the Linux kernel version that includes this fix once it is released. Patch status is not explicitly confirmed in the provided data; therefore, check the official Linux kernel advisories or vendor updates for the exact fixed versions and apply them accordingly.