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Commit 7cb35119 authored by Miklos Szeredi's avatar Miklos Szeredi
Browse files

ovl: listxattr: use strnlen() 



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: default avatarMiklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
parent 0eb45fc3

fs/overlayfs/inode.c

+10 −7
Original line number Diff line number Diff line
@@ -255,7 +255,8 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size) 
{

	struct dentry *realdentry = ovl_dentry_real(dentry);

	ssize_t res;

	int off;

	size_t len;

	char *s;

	const struct cred *old_cred;



	old_cred = ovl_override_creds(dentry->d_sb);
@@ -265,17 +266,19 @@ 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;

		}

	}