From 240e715aed9ea8b1a6d3b89c84cf9af3c3436e6f Mon Sep 17 00:00:00 2001
From: Anton Kling <anton@kling.gg>
Date: Thu, 9 Nov 2023 23:20:58 +0100
Subject: Kernel/fs: Dynamically allocate depending upon file size of
directory.
This also solves a bug where the data_p pointer could get out of range
due to incorrect assumptions being made about the ext2 directory layout.
To be fair even a faulty ext2 directory layout should not be able to
cause memory bugs.
---
kernel/fs/ext2.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
(limited to 'kernel/fs/ext2.c')
diff --git a/kernel/fs/ext2.c b/kernel/fs/ext2.c
index bd0fb07..b4d7716 100644
--- a/kernel/fs/ext2.c
+++ b/kernel/fs/ext2.c
@@ -165,14 +165,20 @@ void ext2_write_inode(int inode_index, inode_t *data) {
int ext2_get_inode_in_directory(int dir_inode, char *file,
direntry_header_t *entry) {
- // FIXME: Allocate sufficent size each time
- unsigned char *data = kmalloc(block_byte_size * 5);
+ uint64_t file_size;
+ ASSERT_BUT_FIXME_PROPOGATE(-1 !=
+ read_inode(dir_inode, NULL, 0, 0, &file_size));
+ uint64_t allocation_size = file_size;
+ unsigned char *data = kmalloc(allocation_size);
ASSERT_BUT_FIXME_PROPOGATE(
- -1 != read_inode(dir_inode, data, block_byte_size * 5, 0, 0));
+ -1 != read_inode(dir_inode, data, allocation_size, 0, NULL));
direntry_header_t *dir;
unsigned char *data_p = data;
- for (; (dir = (direntry_header_t *)data_p)->inode; data_p += dir->size) {
+ unsigned char *data_end = data + allocation_size;
+ for (; data_p <= (data_end - sizeof(direntry_header_t)) &&
+ (dir = (direntry_header_t *)data_p)->inode;
+ data_p += dir->size) {
if (0 == dir->size)
break;
if (0 == dir->name_length)
--
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