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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>
This commit is contained in:
Phillip Lougher 2013-09-04 02:58:12 +01:00
parent f960cae535
commit 9e01242386
2 changed files with 9 additions and 3 deletions
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7
fs/squashfs/dir.c
View File

@ -112,8 +112,8 @@ static int squashfs_readdir(struct file *file, struct dir_context *ctx)
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 @@ static int squashfs_readdir(struct file *file, struct dir_context *ctx)
((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]))

5
fs/squashfs/squashfs_fs.h
View File

@ -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