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-rw-r--r--fs/squashfs/id.c42
1 files changed, 26 insertions, 16 deletions
diff --git a/fs/squashfs/id.c b/fs/squashfs/id.c
index d8f32452638e..a70858e0fb44 100644
--- a/fs/squashfs/id.c
+++ b/fs/squashfs/id.c
@@ -2,7 +2,7 @@
* Squashfs - a compressed read only filesystem for Linux
*
* Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008
- * Phillip Lougher <phillip@lougher.demon.co.uk>
+ * Phillip Lougher <phillip@squashfs.org.uk>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
@@ -66,27 +66,37 @@ int squashfs_get_id(struct super_block *sb, unsigned int index,
* Read uncompressed id lookup table indexes from disk into memory
*/
__le64 *squashfs_read_id_index_table(struct super_block *sb,
- u64 id_table_start, unsigned short no_ids)
+ u64 id_table_start, u64 next_table, unsigned short no_ids)
{
unsigned int length = SQUASHFS_ID_BLOCK_BYTES(no_ids);
- __le64 *id_table;
- int err;
+ __le64 *table;
TRACE("In read_id_index_table, length %d\n", length);
- /* Allocate id lookup table indexes */
- id_table = kmalloc(length, GFP_KERNEL);
- if (id_table == NULL) {
- ERROR("Failed to allocate id index table\n");
- return ERR_PTR(-ENOMEM);
- }
+ /* Sanity check values */
+
+ /* there should always be at least one id */
+ if (no_ids == 0)
+ return ERR_PTR(-EINVAL);
+
+ /*
+ * length bytes should not extend into the next table - this check
+ * also traps instances where id_table_start is incorrectly larger
+ * than the next table start
+ */
+ if (id_table_start + length > next_table)
+ return ERR_PTR(-EINVAL);
+
+ table = squashfs_read_table(sb, id_table_start, length);
- err = squashfs_read_table(sb, id_table, id_table_start, length);
- if (err < 0) {
- ERROR("unable to read id index table\n");
- kfree(id_table);
- return ERR_PTR(err);
+ /*
+ * table[0] points to the first id lookup table metadata block, this
+ * should be less than id_table_start
+ */
+ if (!IS_ERR(table) && table[0] >= id_table_start) {
+ kfree(table);
+ return ERR_PTR(-EINVAL);
}
- return id_table;
+ return table;
}