CVE-2026-98930KVM: s390: Fix IRQ injection with SIGP Stop and Store Status

Official description

In the Linux kernel, the following vulnerability has been resolved: KVM: s390: Fix IRQ injection with SIGP Stop and Store Status When __inject_sigp_stop() is called for a Stop and Store Status operation, if the vCPU is running, the interrupt is marked as pending and the status is stored by the thread performing the KVM_RUN IOCTL. If the vCPU is already stopped, the status is stored immediately. Storing the status means writing into userspace, which might fault, and __inject_sigp_stop() is called from do_inject_vcpu() which in turn is always called holding a spinlock, which is obviously an issue. Fix this by returning -EWOULDBLOCK from __inject_sigp_stop(), and adding a bool flag to indicate whether a store status is needed. The callers of do_inject_vcpu() are modified to pass the pointer to the bool flag; whenever a Store Status operation is needed, the callers can now perform it outside the spinlock. Opportunistically refactor kvm_s390_set_irq_state() to use scoped_guard() and __free(). [ Added Fixes tag while picking -- Claudio ]

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/3bd77c59576b1d447fd56cc689ae9523a334b924
• https://git.kernel.org/stable/c/a379ac504fcb8c6fc2aa36203f5489b9581eb2e0
• https://git.kernel.org/stable/c/d0e3bf633f0585a0c2c2105ea7723777d764fae5
• https://git.kernel.org/stable/c/d343407b728a80b74be3c24b59f15e60289ea527