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commit b5020a8e6b54d2ece80b1e7dedb33c79a40ebd47 upstream. Syzbot reports crashes in kvm_irqfd_assign(), caused by use-after-free when kvm_irqfd_assign() and kvm_irqfd_deassign() run in parallel for one specific eventfd. When the assign path hasn't finished but irqfd has been added to kvm->irqfds.items list, another thead may deassign the eventfd and free struct kvm_kernel_irqfd(). The assign path then uses the struct kvm_kernel_irqfd that has been freed by deassign path. To avoid such issue, keep irqfd under kvm->irq_srcu protection after the irqfd has been added to kvm->irqfds.items list, and call synchronize_srcu() in irq_shutdown() to make sure that irqfd has been fully initialized in the assign path. Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Tianyu Lan <tianyu.lan@intel.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.