VisionFive2 Linux kernel

StarFive Tech Linux Kernel for VisionFive (JH7110) boards (mirror)

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author: Paolo Bonzini <pbonzini@redhat.com> 2021-08-04 05:28:52 -0400 committer: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 2021-08-12 13:32:23 +0200 commit: 16375248cec6eb31b69391c5d2c4515d735aa07c parent: 9a6772458f8eaa54a4558935e94db27d29a7a3ad
Commit Summary:
KVM: Do not leak memory for duplicate debugfs directories
Diffstat:
1 file changed, 16 insertions, 2 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0119466677b7..1dcc66060a19 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -845,6 +845,8 @@ static void kvm_destroy_vm_debugfs(struct kvm *kvm)
 
 static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
 {
+	static DEFINE_MUTEX(kvm_debugfs_lock);
+	struct dentry *dent;
 	char dir_name[ITOA_MAX_LEN * 2];
 	struct kvm_stat_data *stat_data;
 	struct kvm_stats_debugfs_item *p;
@@ -853,8 +855,20 @@ static int kvm_create_vm_debugfs(struct kvm *kvm, int fd)
 		return 0;
 
 	snprintf(dir_name, sizeof(dir_name), "%d-%d", task_pid_nr(current), fd);
-	kvm->debugfs_dentry = debugfs_create_dir(dir_name, kvm_debugfs_dir);
+	mutex_lock(&kvm_debugfs_lock);
+	dent = debugfs_lookup(dir_name, kvm_debugfs_dir);
+	if (dent) {
+		pr_warn_ratelimited("KVM: debugfs: duplicate directory %s\n", dir_name);
+		dput(dent);
+		mutex_unlock(&kvm_debugfs_lock);
+		return 0;
+	}
+	dent = debugfs_create_dir(dir_name, kvm_debugfs_dir);
+	mutex_unlock(&kvm_debugfs_lock);
+	if (IS_ERR(dent))
+		return 0;
 
+	kvm->debugfs_dentry = dent;
 	kvm->debugfs_stat_data = kcalloc(kvm_debugfs_num_entries,
 					 sizeof(*kvm->debugfs_stat_data),
 					 GFP_KERNEL_ACCOUNT);
@@ -4993,7 +5007,7 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
 	}
 	add_uevent_var(env, "PID=%d", kvm->userspace_pid);
 
-	if (!IS_ERR_OR_NULL(kvm->debugfs_dentry)) {
+	if (kvm->debugfs_dentry) {
 		char *tmp, *p = kmalloc(PATH_MAX, GFP_KERNEL_ACCOUNT);
 
 		if (p) {