Squashfs: add corruption check for type in squashfs_readdir()
We read the type field from disk. This value should be sanity
checked for correctness to avoid an out of bounds access when
reading the squashfs_filetype_table array.
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
diff --git a/fs/squashfs/dir.c b/fs/squashfs/dir.c
index bd7155b..d8c2d74 100644
--- a/fs/squashfs/dir.c
+++ b/fs/squashfs/dir.c
@@ -112,8 +112,8 @@
struct inode *inode = file_inode(file);
struct squashfs_sb_info *msblk = inode->i_sb->s_fs_info;
u64 block = squashfs_i(inode)->start + msblk->directory_table;
- int offset = squashfs_i(inode)->offset, length, type, err;
- unsigned int inode_number, dir_count, size;
+ int offset = squashfs_i(inode)->offset, length, err;
+ unsigned int inode_number, dir_count, size, type;
struct squashfs_dir_header dirh;
struct squashfs_dir_entry *dire;
@@ -206,6 +206,9 @@
((short) le16_to_cpu(dire->inode_number));
type = le16_to_cpu(dire->type);
+ if (type > SQUASHFS_MAX_DIR_TYPE)
+ goto failed_read;
+
if (!dir_emit(ctx, dire->name, size,
inode_number,
squashfs_filetype_table[type]))
diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h
index 9e2349d..4b2beda 100644
--- a/fs/squashfs/squashfs_fs.h
+++ b/fs/squashfs/squashfs_fs.h
@@ -87,7 +87,7 @@
#define SQUASHFS_COMP_OPTS(flags) SQUASHFS_BIT(flags, \
SQUASHFS_COMP_OPT)
-/* Max number of types and file types */
+/* Inode types including extended types */
#define SQUASHFS_DIR_TYPE 1
#define SQUASHFS_REG_TYPE 2
#define SQUASHFS_SYMLINK_TYPE 3
@@ -103,6 +103,9 @@
#define SQUASHFS_LFIFO_TYPE 13
#define SQUASHFS_LSOCKET_TYPE 14
+/* Max type value stored in directory entry */
+#define SQUASHFS_MAX_DIR_TYPE 7
+
/* Xattr types */
#define SQUASHFS_XATTR_USER 0
#define SQUASHFS_XATTR_TRUSTED 1