From 7a173276f96f2d30c043c22ee98c9ea28622fb9e Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Thu, 1 Sep 2016 11:12:00 +0200 Subject: ovl: listxattr: use strnlen() [ Upstream commit 7cb35119d067191ce9ebc380a599db0b03cbd9d9 ] 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 Cc: Signed-off-by: Sasha Levin --- fs/overlayfs/inode.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-) diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c index 69d715122598..0bb8347c0d8b 100644 --- a/fs/overlayfs/inode.c +++ b/fs/overlayfs/inode.c @@ -279,7 +279,8 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) 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) @@ -289,17 +290,19 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) 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; } } -- cgit v1.2.3