4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Miklos Szeredi <[email protected]> commit 7cb35119d067191ce9ebc380a599db0b03cbd9d9 upstream. Be defensive about what underlying fs provides us in the returned xattr list buffer. If it's not properly null terminated, bail out with a warning insead of BUG. Signed-off-by: Miklos Szeredi <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- fs/overlayfs/inode.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -277,7 +277,8 @@ ssize_t ovl_listxattr(struct dentry *den struct path realpath; enum ovl_path_type type = ovl_path_real(dentry, &realpath); ssize_t res; - int off; + size_t len; + char *s; res = vfs_listxattr(realpath.dentry, list, size); if (res <= 0 || size == 0) @@ -287,17 +288,19 @@ ssize_t ovl_listxattr(struct dentry *den return res; /* filter out private xattrs */ - for (off = 0; off < res;) { - char *s = list + off; - size_t slen = strlen(s) + 1; + for (s = list, len = res; len;) { + size_t slen = strnlen(s, len) + 1; - BUG_ON(off + slen > res); + /* underlying fs providing us with an broken xattr list? */ + if (WARN_ON(slen > len)) + return -EIO; + len -= slen; if (ovl_is_private_xattr(s)) { res -= slen; - memmove(s, s + slen, res - off); + memmove(s, s + slen, len); } else { - off += slen; + s += slen; } }
