vhost_vdpa: assign irq bypass producer token correctly

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: vhost_vdpa: assign irq bypass producer token correctly We used to call irq_bypass_unregister_producer() in vhost_vdpa_setup_vq_irq() which is problematic as we don't know if the token pointer is still valid or not. Actually, we use the eventfd_ctx as the token so the life cycle of the token should be bound to the VHOST_SET_VRING_CALL instead of vhost_vdpa_setup_vq_irq() which could be called by set_status(). Fixing this by setting up irq bypass producer's token when handling VHOST_SET_VRING_CALL and un-registering the producer before calling vhost_vring_ioctl() to prevent a possible use after free as eventfd could have been released in vhost_vring_ioctl(). And such registering and unregistering will only be done if DRIVER_OK is set.

References

• https://git.kernel.org/stable/c/0c170b1e918b9afac25e2bbd01eaa2bfc0ece8c0
• https://git.kernel.org/stable/c/927a2580208e0f9b0b47b08f1c802b7233a7ba3c
• https://git.kernel.org/stable/c/ec5f1b54ceb23475049ada6e7a43452cf4df88d1
• https://git.kernel.org/stable/c/ca64edd7ae93402af2596a952e0d94d545e2b9c0
• https://git.kernel.org/stable/c/fae9b1776f53aab93ab345bdbf653b991aed717d
• https://git.kernel.org/stable/c/7cf2fb51175cafe01df8c43fa15a06194a59c6e2
• https://git.kernel.org/stable/c/02e9e9366fefe461719da5d173385b6685f70319