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authorOliver Upton <oupton@google.com>2022-04-06 23:56:13 +0000
committerMarc Zyngier <maz@kernel.org>2022-04-07 08:46:13 +0100
commita44a4cc1c969afec97dbb2aedaf6f38eaa6253bb (patch)
tree9d17a264e3770296f052f2bb4419ad218632232d /virt
parent02de9331c4d0c6bddac9c5fa66d91f70adf8612b (diff)
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KVM: Don't create VM debugfs files outside of the VM directory
Unfortunately, there is no guarantee that KVM was able to instantiate a debugfs directory for a particular VM. To that end, KVM shouldn't even attempt to create new debugfs files in this case. If the specified parent dentry is NULL, debugfs_create_file() will instantiate files at the root of debugfs. For arm64, it is possible to create the vgic-state file outside of a VM directory, the file is not cleaned up when a VM is destroyed. Nonetheless, the corresponding struct kvm is freed when the VM is destroyed. Nip the problem in the bud for all possible errant debugfs file creations by initializing kvm->debugfs_dentry to -ENOENT. In so doing, debugfs_create_file() will fail instead of creating the file in the root directory. Cc: stable@kernel.org Fixes: 929f45e32499 ("kvm: no need to check return value of debugfs_create functions") Signed-off-by: Oliver Upton <oupton@google.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Link: https://lore.kernel.org/r/20220406235615.1447180-2-oupton@google.com
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/kvm_main.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 70e05af5ebea..e39a6f56fc47 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -932,7 +932,7 @@ static void kvm_destroy_vm_debugfs(struct kvm *kvm)
int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc +
kvm_vcpu_stats_header.num_desc;
- if (!kvm->debugfs_dentry)
+ if (IS_ERR(kvm->debugfs_dentry))
return;
debugfs_remove_recursive(kvm->debugfs_dentry);
@@ -955,6 +955,12 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
int kvm_debugfs_num_entries = kvm_vm_stats_header.num_desc +
kvm_vcpu_stats_header.num_desc;
+ /*
+ * Force subsequent debugfs file creations to fail if the VM directory
+ * is not created.
+ */
+ kvm->debugfs_dentry = ERR_PTR(-ENOENT);
+
if (!debugfs_initialized())
return 0;
@@ -5479,7 +5485,7 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
}
add_uevent_var(env, "PID=%d", kvm->userspace_pid);
- if (kvm->debugfs_dentry) {
+ if (!IS_ERR(kvm->debugfs_dentry)) {
char *tmp, *p = kmalloc(PATH_MAX, GFP_KERNEL_ACCOUNT);
if (p) {