Re: [PATCH] kvm tool: Don't close not yet opened files and SIGSEV fix

[Cyrill Gorcunov <gorcunov@openvz.org>]

On Sat, Feb 04, 2012 at 10:02:19PM +0400, Cyrill Gorcunov wrote:
> 
> Strictly speaking, kvm__init need more serious rewrite together with
> kvm__arch_init/kvm_ipc__start/kvm_ipc__register_handler ret. vals tests,
> i'll do this a bit late.
> 

Sorry for delay, was busy. Anyway, here is a quickfix for sigsev and close()s.

	Cyrill
---
Subject: kvm tool: Don't close not yet opened files and SIGSEV fix

In case if there error happened in kvm__init and we have
no files opened -- we should not try to close them.

Also once kvm failed to init the caller should not try
to dereference a pointer obtained, otherwise we might get
SIGSEV

 | [cyrill@moon kvm]$ ./lkvm run ...
 | Error: '/dev/kvm' not found. Please make sure your kernel has CONFIG_KVM
 | enabled and that the KVM modules are loaded.
 | Segmentation fault (core dumped)
 | [cyrill@moon kvm]$

Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
---
 tools/kvm/builtin-run.c |    4 ++++
 tools/kvm/kvm.c         |   41 +++++++++++++++++++++--------------------
 2 files changed, 25 insertions(+), 20 deletions(-)

Index: linux-2.6.git/tools/kvm/builtin-run.c
===================================================================
--- linux-2.6.git.orig/tools/kvm/builtin-run.c
+++ linux-2.6.git/tools/kvm/builtin-run.c
@@ -997,6 +997,10 @@ static int kvm_cmd_run_init(int argc, co
 	}
 
 	kvm = kvm__init(dev, hugetlbfs_path, ram_size, guest_name);
+	if (IS_ERR(kvm)) {
+		r = PTR_ERR(kvm);
+		goto fail;
+	}
 
 	kvm->single_step = single_step;
 
Index: linux-2.6.git/tools/kvm/kvm.c
===================================================================
--- linux-2.6.git.orig/tools/kvm/kvm.c
+++ linux-2.6.git/tools/kvm/kvm.c
@@ -123,10 +123,12 @@ static int kvm__check_extensions(struct
 static struct kvm *kvm__new(void)
 {
 	struct kvm *kvm = calloc(1, sizeof(*kvm));
-
 	if (!kvm)
 		return ERR_PTR(-ENOMEM);
 
+	kvm->sys_fd = -1;
+	kvm->vm_fd = -1;
+
 	return kvm;
 }
 
@@ -341,47 +343,42 @@ struct kvm *kvm__init(const char *kvm_de
 	}
 
 	kvm = kvm__new();
-	if (IS_ERR_OR_NULL(kvm))
+	if (IS_ERR(kvm))
 		return kvm;
 
 	kvm->sys_fd = open(kvm_dev, O_RDWR);
 	if (kvm->sys_fd < 0) {
-		if (errno == ENOENT) {
+		if (errno == ENOENT)
 			pr_err("'%s' not found. Please make sure your kernel has CONFIG_KVM "
-				"enabled and that the KVM modules are loaded.", kvm_dev);
-			ret = -errno;
-			goto cleanup;
-		}
-		if (errno == ENODEV) {
-			die("'%s' KVM driver not available.\n  # (If the KVM "
-				"module is loaded then 'dmesg' may offer further clues "
-				"about the failure.)", kvm_dev);
-			ret = -errno;
-			goto cleanup;
-		}
+			       "enabled and that the KVM modules are loaded.", kvm_dev);
+		else if (errno == ENODEV)
+			pr_err("'%s' KVM driver not available.\n  # (If the KVM "
+			       "module is loaded then 'dmesg' may offer further clues "
+			       "about the failure.)", kvm_dev);
+		else
+			pr_err("Could not open %s: ", kvm_dev);
 
-		pr_err("Could not open %s: ", kvm_dev);
 		ret = -errno;
-		goto cleanup;
+		goto err_free;
 	}
 
 	ret = ioctl(kvm->sys_fd, KVM_GET_API_VERSION, 0);
 	if (ret != KVM_API_VERSION) {
 		pr_err("KVM_API_VERSION ioctl");
 		ret = -errno;
-		goto cleanup;
+		goto err_sys_fd;
 	}
 
 	kvm->vm_fd = ioctl(kvm->sys_fd, KVM_CREATE_VM, 0);
 	if (kvm->vm_fd < 0) {
 		ret = kvm->vm_fd;
-		goto cleanup;
+		goto err_sys_fd;
 	}
 
 	kvm->name = strdup(name);
 	if (!kvm->name) {
 		ret = -ENOMEM;
-		goto cleanup;
+		goto err;
 	}
 
 	if (kvm__check_extensions(kvm)) {
@@ -393,10 +390,14 @@ struct kvm *kvm__init(const char *kvm_de
 
 	kvm_ipc__start(kvm__create_socket(kvm));
 	kvm_ipc__register_handler(KVM_IPC_PID, kvm__pid);
+
 	return kvm;
-cleanup:
+
+err:
 	close(kvm->vm_fd);
+err_sys_fd:
 	close(kvm->sys_fd);
+err_free:
 	free(kvm);
 
 	return ERR_PTR(ret);