[PATCH] ceph: fix getxattr return values for vxattrs

7 Jun 2019

We have several virtual xattrs in cephfs which return various values as
strings. xattrs don't necessarily return strings however, so we need to
include the terminating NULL byte in the length when we return the
length.

Furthermore, the getxattr manpage says that we should return -ERANGE if
the buffer is too small to hold the resulting value. Let's start doing
that here as well.

URL: https://bugzilla.redhat.com/show_bug.cgi?id=1717454
Reported-by: Tomas Petr <tpetr@redhat.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
 fs/ceph/xattr.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c
index 6621d27e64f5..57f1bd83c21c 100644
--- a/fs/ceph/xattr.c
+++ b/fs/ceph/xattr.c
@@ -803,8 +803,14 @@ ssize_t __ceph_getxattr(struct inode *inode, const char *name, void *value,
 		if (err)
 			return err;
 		err = -ENODATA;
-		if (!(vxattr->exists_cb && !vxattr->exists_cb(ci)))
-			err = vxattr->getxattr_cb(ci, value, size);
+		if (!(vxattr->exists_cb && !vxattr->exists_cb(ci))) {
+			/* Make sure result will fit in buffer */
+			if (size > 0) {
+				if (size < vxattr->getxattr_cb(ci, NULL, 0) + 1)
+					return -ERANGE;
+			}
+			err = vxattr->getxattr_cb(ci, value, size) + 1;
+		}
 		return err;
 	}
 
-- 
2.21.0

    

Jeff Layton

Patrick Donnelly

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