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 <[email protected]>

---
tools/kvm/builtin-run.c | 4 ++++
tools/kvm/kvm.c | 11 ++++++++---

2 files changed, 12 insertions(+), 3 deletions(-)

Index: linux-2.6.git/tools/kvm/builtin-run.c
===================================================================

tools/kvm/builtin-run.c +3 -0

+		r = PTR_ERR(kvm);
+		goto fail;
+	}

Quoted 25 lines · Cyrill Gorcunov

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 <[email protected]>

---
tools/kvm/builtin-run.c | 4 ++++
tools/kvm/kvm.c | 11 ++++++++---

2 files changed, 12 insertions(+), 3 deletions(-)

Index: linux-2.6.git/tools/kvm/builtin-run.c
===================================================================

tools/kvm/builtin-run.c +0 -0

@@ -997,6 +997,10 @@ static int kvm_cmd_run_init(int argc, co
 	}
 

tools/kvm/builtin-run.c static int kvm_cmd_run_init(int argc, co · line 1000

Quoted 2 lines

tools/kvm/builtin-run.c +1 -0

 	kvm = kvm__init(dev, hugetlbfs_path, ram_size, guest_name);
+	if (IS_ERR_OR_NULL(kvm)) {

PTR_ERR is still not going to work if kvm is NULL.

Index: linux-2.6.git/tools/kvm/kvm.c
===================================================================

tools/kvm/kvm.c +4 -1

@@ -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;
 }
 

@@ -394,9 +396,12 @@ 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:

	free(kvm);

	return ERR_PTR(ret);

Quoted 18 lines · Cyrill Gorcunov

Index: linux-2.6.git/tools/kvm/kvm.c
===================================================================

tools/kvm/kvm.c +3 -1

@@ -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;
 }
 

tools/kvm/kvm.c struct kvm *kvm__init(const char *kvm_de · line 404

Quoted 12 lines

tools/kvm/kvm.c +1 -0

@@ -394,9 +396,12 @@ 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:

tools/kvm/kvm.c +4 -2

-	close(kvm->vm_fd);
-	close(kvm->sys_fd);
+	if (kvm->vm_fd >= 0)
+		close(kvm->vm_fd);
+	if (kvm->sys_fd >= 0)
+		close(kvm->sys_fd);

No, please don't do this! Use specific error handling labels instead.

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.