From: Sean Christopherson seanjc@google.com
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 zheng.zhang@email.ucr.edu Closes: https://lore.kernel.org/all/CAC_GQSr3xzZaeZt85k_RCBd5kfiOve8qXo7a81Cq53LuVQ5... Cc: stable@vger.kernel.org Cc: Kees Cook keescook@chromium.org Signed-off-by: Sean Christopherson seanjc@google.com Reviewed-by: Kees Cook keescook@chromium.org Message-Id: 20230711230131.648752-2-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- virt/kvm/kvm_main.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)
--- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4032,8 +4032,17 @@ static ssize_t kvm_vcpu_stats_read(struc 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, };
@@ -4054,6 +4063,9 @@ static int kvm_vcpu_ioctl_get_stats_fd(s put_unused_fd(fd); return PTR_ERR(file); } + + kvm_get_kvm(vcpu->kvm); + file->f_mode |= FMODE_PREAD; fd_install(fd, file);
@@ -4658,8 +4670,17 @@ static ssize_t kvm_vm_stats_read(struct 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, };
@@ -4678,6 +4699,9 @@ static int kvm_vm_ioctl_get_stats_fd(str put_unused_fd(fd); return PTR_ERR(file); } + + kvm_get_kvm(kvm); + file->f_mode |= FMODE_PREAD; fd_install(fd, file);