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| author | Phillip Lougher <phillip@lougher.demon.co.uk> | 2011-03-15 22:09:55 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2011-04-14 16:53:11 -0700 |
| commit | 6f5ff91733db188b0cbcc59482dbc7e20b17d56d (patch) | |
| tree | 7f65f8d6782c98bffe29e2ba7b8539ec91216f08 | |
| parent | 98eec152c36e9544a81fa709d0eb2cf028cf4cdb (diff) | |
| download | lwn-6f5ff91733db188b0cbcc59482dbc7e20b17d56d.tar.gz lwn-6f5ff91733db188b0cbcc59482dbc7e20b17d56d.zip | |
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 <phillip@lougher.demon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | fs/squashfs/dir.c | 9 | ||||
| -rw-r--r-- | fs/squashfs/namei.c | 12 |
2 files changed, 21 insertions, 0 deletions
diff --git a/fs/squashfs/dir.c b/fs/squashfs/dir.c index 566b0eaed868..16c1b4a533b2 100644 --- a/fs/squashfs/dir.c +++ b/fs/squashfs/dir.c @@ -173,6 +173,11 @@ 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. @@ -184,6 +189,10 @@ 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 9e398653b22b..ac527512f073 100644 --- a/fs/squashfs/namei.c +++ b/fs/squashfs/namei.c @@ -175,6 +175,11 @@ 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. @@ -186,6 +191,10 @@ 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) @@ -227,6 +236,9 @@ 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, |