Messages in this thread Patch in this message | | | From | Andi Kleen <> | Subject | [PATCH] [43/106] Squashfs: handle corruption of directory structure | Date | Tue, 26 Apr 2011 14:13:22 -0700 (PDT) |
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2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: Phillip Lougher <phillip@lougher.demon.co.uk>
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> Signed-off-by: Andi Kleen <ak@linux.intel.com>
--- fs/squashfs/dir.c | 9 +++++++++ fs/squashfs/namei.c | 12 ++++++++++++ 2 files changed, 21 insertions(+)
Index: linux-2.6.35.y/fs/squashfs/dir.c =================================================================== --- linux-2.6.35.y.orig/fs/squashfs/dir.c +++ linux-2.6.35.y/fs/squashfs/dir.c @@ -172,6 +172,11 @@ static int squashfs_readdir(struct file 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 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) Index: linux-2.6.35.y/fs/squashfs/namei.c =================================================================== --- linux-2.6.35.y.orig/fs/squashfs/namei.c +++ linux-2.6.35.y/fs/squashfs/namei.c @@ -176,6 +176,11 @@ static struct dentry *squashfs_lookup(st 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(st 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,
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