kernel: implement virt_cpy2kmalloc

2 files changed, 18 insertions, 7 deletions

diff --git a/src/kernel/mem/virt.h b/src/kernel/mem/virt.h
index 3a42e9e..b858bdd 100644
--- a/src/kernel/mem/virt.h
+++ b/src/kernel/mem/virt.h
@@ -1,5 +1,6 @@
 /* contains utilities for interacting with virtual memory */
 #pragma once
+#include <kernel/mem/alloc.h>
 #include <shared/types.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -38,3 +39,15 @@ static inline bool virt_cpy_from(struct pagedir *src_pages, // virtual -> physic
 		void *dest, const void __user *src, size_t length) {
 	return virt_cpy(NULL, (userptr_t)dest, src_pages, src, length);
 }
+
+/** Copies a chunk of virtual memory to a newly kmalloc'd buffer. */
+static inline void *virt_cpy2kmalloc(struct pagedir *src_pages,
+		const void __user *src, size_t length) {
+	void *buf = kmalloc(length);
+	if (virt_cpy_from(src_pages, buf, src, length)) {
+		return buf;
+	} else {
+		kfree(buf);
+		return NULL;
+	}
+}
diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index 22bf1f6..a819b64 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -49,10 +49,8 @@ handle_t _syscall_open(const char __user *path, int len) {
 	if (process_find_handle(process_current) < 0)
 		return -1;
 
-	// copy the path to the kernel, simplify it
-	path_buf = kmalloc(len); // gets freed in vfs_request_finish
-	if (!virt_cpy_from(process_current->pages, path_buf, path, len))
-		goto fail;
+	path_buf = virt_cpy2kmalloc(process_current->pages, path, len);
+	if (!path_buf) goto fail;
 
 	len = path_simplify(path_buf, path_buf, len);
 	if (len < 0) goto fail;
@@ -90,9 +88,9 @@ int _syscall_mount(handle_t handle, const char __user *path, int len) {
 	if (PATH_MAX < len) return -1;
 
 	// copy the path to the kernel to simplify it
-	path_buf = kmalloc(len);
-	if (!virt_cpy_from(process_current->pages, path_buf, path, len))
-		goto fail;
+	path_buf = virt_cpy2kmalloc(process_current->pages, path, len);
+	if (!path_buf) goto fail;
+
 	len = path_simplify(path_buf, path_buf, len);
 	if (len < 0) goto fail;