From 9ec2aeb349d3d935f61c195244b6464e939f4b51 Mon Sep 17 00:00:00 2001
From: Aleksa Vuckovic <aleksav013@gmail.com>
Date: Sun, 4 Dec 2022 21:28:25 +0100
Subject: ext2.c: terminating buff; handling incorrect use

---
 kernel/src/fs/ext2.c     | 24 +++++++++++++++++++++---
 kernel/src/libk/string.c |  3 +++
 kernel/src/main.c        |  1 +
 3 files changed, 25 insertions(+), 3 deletions(-)

(limited to 'kernel/src')

diff --git a/kernel/src/fs/ext2.c b/kernel/src/fs/ext2.c
index 751cf64..f4460c7 100644
--- a/kernel/src/fs/ext2.c
+++ b/kernel/src/fs/ext2.c
@@ -122,6 +122,10 @@ dentry_list_t* directory_to_entries(uint32_t inode)
 
 char* files_to_buffer(uint32_t inode)
 {
+	if (inode < 2) {
+		return NULL;
+	}
+
 	uint32_t bg_desc = (inode - 1) / ext2_superblock->inodes_per_group;
 	uint32_t inode_index = (inode - 1) % ext2_superblock->inodes_per_group;
 
@@ -135,10 +139,17 @@ char* files_to_buffer(uint32_t inode)
 	ext2_inode = (ext2_inode_t*)kalloc(sizeof(ext2_inode_t));
 	read_inode(ext2_bg_desc->inode_block_address, inode_index, ext2_inode);
 
+	if (ext2_inode->type_perms & TYPE_DIR) {
+		printf("can't print directory\n");
+		kfree(ext2_bg_desc);
+		kfree(ext2_inode);
+		return NULL;
+	}
+
 	char* data;
 
 	uint32_t size = ext2_inode->size_lower;
-	data = (char*)kalloc(size);
+	data = (char*)kalloc(size + 1);
 
 	uint32_t block_num = upper_div(size, BLOCK_SIZE);
 	for (size_t i = 0; i < min(block_num, 12); i++) {
@@ -146,6 +157,10 @@ char* files_to_buffer(uint32_t inode)
 		read_block(ext2_inode->dbp[i], block);
 		memcpy(data + i * BLOCK_SIZE, block, size >= (i + 1) * BLOCK_SIZE ? BLOCK_SIZE : size % BLOCK_SIZE);
 	}
+	data[size] = '\0';
+
+	kfree(ext2_bg_desc);
+	kfree(ext2_inode);
 
 	return data;
 }
@@ -257,7 +272,10 @@ void ls(uint32_t inode)
 
 void print(uint32_t inode)
 {
-	printf("contents of inode %d:\n", inode);
 	char *p = files_to_buffer(inode);
-	printf("%s", p);
+	if (p != NULL) {
+		printf("contents of inode %d:\n", inode);
+		printf("%s", p);
+		kfree(p);
+	}
 }
diff --git a/kernel/src/libk/string.c b/kernel/src/libk/string.c
index 4cee538..8b2b2c6 100644
--- a/kernel/src/libk/string.c
+++ b/kernel/src/libk/string.c
@@ -3,6 +3,9 @@
 
 size_t strlen(const char* s)
 {
+	if (s == NULL)
+		return 0;
+
 	char *p = (char*)s;
 	while (*p) p++;
 	return (size_t)(p - s);
diff --git a/kernel/src/main.c b/kernel/src/main.c
index 2b4be32..5b55c09 100644
--- a/kernel/src/main.c
+++ b/kernel/src/main.c
@@ -42,6 +42,7 @@ int kernel_main(mb2_tag_header* multiboot_bootinfo, uint32_t multiboot_magic)
 	disc_init();
 	ext2_init();
 	ls(path_to_inode("/"));
+	print(path_to_inode("/"));
 	init_tss();
 	jump_userspace();
 
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