From 714ac6de4454bd134f5bc0777e2bc7c5c50629db Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Fri, 16 Sep 2016 14:12:11 +0200 Subject: ovl: copy_up_xattr(): use strnlen commit 8b326c61de08f5ca4bc454a168f19e7e43c4cc2a upstream. Be defensive about what underlying fs provides us in the returned xattr list buffer. strlen() may overrun the buffer, so use strnlen() and WARN if the contents are not properly null terminated. Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/copy_up.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/overlayfs/copy_up.c b/fs/overlayfs/copy_up.c index 9e52609cd683..ea0dd9ee138d 100644 --- a/fs/overlayfs/copy_up.c +++ b/fs/overlayfs/copy_up.c @@ -25,6 +25,7 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new) ssize_t list_size, size, value_size = 0; char *buf, *name, *value = NULL; int uninitialized_var(error); + size_t slen; if (!old->d_inode->i_op->getxattr || !new->d_inode->i_op->getxattr) @@ -47,7 +48,16 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new) goto out; } - for (name = buf; name < (buf + list_size); name += strlen(name) + 1) { + for (name = buf; list_size; name += slen) { + slen = strnlen(name, list_size) + 1; + + /* underlying fs providing us with an broken xattr list? */ + if (WARN_ON(slen > list_size)) { + error = -EIO; + break; + } + list_size -= slen; + if (ovl_is_private_xattr(name)) continue; retry: -- cgit v1.2.3