From 5883a4e8478d0b3ecf90262951d152ece0d5bb67 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 11 Jul 2023 16:01:25 -0700 Subject: [PATCH] KVM: Grab a reference to KVM for VM and vCPU stats file descriptors commit eed3013faa401aae662398709410a59bb0646e32 upstream. Grab a reference to KVM prior to installing VM and vCPU stats file descriptors to ensure the underlying VM and vCPU objects are not freed until the last reference to any and all stats fds are dropped. Note, the stats paths manually invoke fd_install() and so don't need to grab a reference before creating the file. Fixes: ce55c049459c ("KVM: stats: Support binary stats retrieval for a VCPU") Fixes: fcfe1baeddbf ("KVM: stats: Support binary stats retrieval for a VM") Reported-by: Zheng Zhang Closes: https://lore.kernel.org/all/CAC_GQSr3xzZaeZt85k_RCBd5kfiOve8qXo7a81Cq53LuVQ5r=Q@mail.gmail.com Cc: stable@vger.kernel.org Cc: Kees Cook Signed-off-by: Sean Christopherson Reviewed-by: Kees Cook Message-Id: <20230711230131.648752-2-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- virt/kvm/kvm_main.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 3967184b7d62..d11c581ce9b9 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -3804,8 +3804,17 @@ static ssize_t kvm_vcpu_stats_read(struct file *file, char __user *user_buffer, sizeof(vcpu->stat), user_buffer, size, offset); } +static int kvm_vcpu_stats_release(struct inode *inode, struct file *file) +{ + struct kvm_vcpu *vcpu = file->private_data; + + kvm_put_kvm(vcpu->kvm); + return 0; +} + static const struct file_operations kvm_vcpu_stats_fops = { .read = kvm_vcpu_stats_read, + .release = kvm_vcpu_stats_release, .llseek = noop_llseek, }; @@ -3826,6 +3835,9 @@ static int kvm_vcpu_ioctl_get_stats_fd(struct kvm_vcpu *vcpu) put_unused_fd(fd); return PTR_ERR(file); } + + kvm_get_kvm(vcpu->kvm); + file->f_mode |= FMODE_PREAD; fd_install(fd, file); @@ -4409,8 +4421,17 @@ static ssize_t kvm_vm_stats_read(struct file *file, char __user *user_buffer, sizeof(kvm->stat), user_buffer, size, offset); } +static int kvm_vm_stats_release(struct inode *inode, struct file *file) +{ + struct kvm *kvm = file->private_data; + + kvm_put_kvm(kvm); + return 0; +} + static const struct file_operations kvm_vm_stats_fops = { .read = kvm_vm_stats_read, + .release = kvm_vm_stats_release, .llseek = noop_llseek, }; @@ -4429,6 +4450,9 @@ static int kvm_vm_ioctl_get_stats_fd(struct kvm *kvm) put_unused_fd(fd); return PTR_ERR(file); } + + kvm_get_kvm(kvm); + file->f_mode |= FMODE_PREAD; fd_install(fd, file);