From 44cff8a9ee8a974f9e931df910688e7fc1f0b0f9 Mon Sep 17 00:00:00 2001 From: Phillip Lougher Date: Tue, 15 Mar 2011 22:09:55 +0000 Subject: Squashfs: handle corruption of directory structure Handle the rare case where a directory metadata block is uncompressed and corrupted, leading to a kernel oops in directory scanning (memcpy). Normally corruption is detected at the decompression stage and dealt with then, however, this will not happen if: - metadata isn't compressed (users can optionally request no metadata compression), or - the compressed metadata block was larger than the original, in which case the uncompressed version was used, or - the data was corrupt after decompression This patch fixes this by adding some sanity checks against known maximum values. Signed-off-by: Phillip Lougher --- fs/squashfs/namei.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'fs/squashfs/namei.c') diff --git a/fs/squashfs/namei.c b/fs/squashfs/namei.c index 7a9464d08cf6..5d922a6701ab 100644 --- a/fs/squashfs/namei.c +++ b/fs/squashfs/namei.c @@ -176,6 +176,11 @@ static struct dentry *squashfs_lookup(struct inode *dir, struct dentry *dentry, length += sizeof(dirh); dir_count = le32_to_cpu(dirh.count) + 1; + + /* dir_count should never be larger than 256 */ + if (dir_count > 256) + goto data_error; + while (dir_count--) { /* * Read directory entry. @@ -187,6 +192,10 @@ static struct dentry *squashfs_lookup(struct inode *dir, struct dentry *dentry, size = le16_to_cpu(dire->size) + 1; + /* size should never be larger than SQUASHFS_NAME_LEN */ + if (size > SQUASHFS_NAME_LEN) + goto data_error; + err = squashfs_read_metadata(dir->i_sb, dire->name, &block, &offset, size); if (err < 0) @@ -228,6 +237,9 @@ exit_lookup: d_add(dentry, inode); return ERR_PTR(0); +data_error: + err = -EIO; + read_failure: ERROR("Unable to read directory block [%llx:%x]\n", squashfs_i(dir)->start + msblk->directory_table, -- cgit v1.2.3