From 8748b23d4aae479a1fc7a54eb4e467cb9b2bbd91 Mon Sep 17 00:00:00 2001 From: Phillip Lougher Date: Tue, 15 Mar 2011 22:09:55 +0000 Subject: [PATCH] Squashfs: handle corruption of directory structure commit 44cff8a9ee8a974f9e931df910688e7fc1f0b0f9 upstream. 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 Signed-off-by: Paul Gortmaker --- fs/squashfs/dir.c | 9 +++++++++ fs/squashfs/namei.c | 12 ++++++++++++ 2 files changed, 21 insertions(+) diff --git a/fs/squashfs/dir.c b/fs/squashfs/dir.c index 12b933ac6585..a37d445cfff9 100644 --- a/fs/squashfs/dir.c +++ b/fs/squashfs/dir.c @@ -172,6 +172,11 @@ static int squashfs_readdir(struct file *file, void *dirent, filldir_t filldir) length += sizeof(dirh); dir_count = le32_to_cpu(dirh.count) + 1; + + /* dir_count should never be larger than 256 */ + if (dir_count > 256) + goto failed_read; + while (dir_count--) { /* * Read directory entry. @@ -183,6 +188,10 @@ static int squashfs_readdir(struct file *file, void *dirent, filldir_t filldir) size = le16_to_cpu(dire->size) + 1; + /* size should never be larger than SQUASHFS_NAME_LEN */ + if (size > SQUASHFS_NAME_LEN) + goto failed_read; + err = squashfs_read_metadata(inode->i_sb, dire->name, &block, &offset, size); if (err < 0) diff --git a/fs/squashfs/namei.c b/fs/squashfs/namei.c index 5266bd8ad932..4fa484d2a5e5 100644 --- a/fs/squashfs/namei.c +++ b/fs/squashfs/namei.c @@ -174,6 +174,11 @@ 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. @@ -185,6 +190,10 @@ 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) @@ -226,6 +235,9 @@ 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, -- 2.39.5