linux-kernel - [PATCH v4 2/3] ceph: return -ERANGE if virtual xattr value didn't fit in buffer

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Date:   Mon, 24 Jun 2019 12:27:25 -0400
From:   Jeff Layton <jlayton@...nel.org>
To:     linux-kernel@...r.kernel.org, ceph-devel@...r.kernel.org
Cc:     idryomov@...il.com, zyan@...hat.com, sage@...hat.com,
        agruenba@...hat.com
Subject: [PATCH v4 2/3] ceph: return -ERANGE if virtual xattr value didn't fit in buffer

The getxattr manpage states that we should return ERANGE if the
destination buffer size is too small to hold the value.
ceph_vxattrcb_layout does this internally, but we should be doing
this for all vxattrs.

Fix the only caller of getxattr_cb to check the returned size
against the buffer length and return -ERANGE if it doesn't fit.
Drop the same check in ceph_vxattrcb_layout and just rely on the
caller to handle it.

Signed-off-by: Jeff Layton <jlayton@...nel.org>
---
 fs/ceph/xattr.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/ceph/xattr.c b/fs/ceph/xattr.c
index e90e19e9660b..9b77dca0b786 100644
--- a/fs/ceph/xattr.c
+++ b/fs/ceph/xattr.c
@@ -63,7 +63,7 @@ static ssize_t ceph_vxattrcb_layout(struct ceph_inode_info *ci, char *val,
 	const char *ns_field = " pool_namespace=";
 	char buf[128];
 	size_t len, total_len = 0;
-	int ret;
+	ssize_t ret;
 
 	pool_ns = ceph_try_get_string(ci->i_layout.pool_ns);
 
@@ -87,11 +87,8 @@ static ssize_t ceph_vxattrcb_layout(struct ceph_inode_info *ci, char *val,
 	if (pool_ns)
 		total_len += strlen(ns_field) + pool_ns->len;
 
-	if (!size) {
-		ret = total_len;
-	} else if (total_len > size) {
-		ret = -ERANGE;
-	} else {
+	ret = total_len;
+	if (size >= total_len) {
 		memcpy(val, buf, len);
 		ret = len;
 		if (pool_name) {
@@ -803,8 +800,11 @@ 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)))
+		if (!(vxattr->exists_cb && !vxattr->exists_cb(ci))) {
 			err = vxattr->getxattr_cb(ci, value, size);
+			if (size && size < err)
+				err = -ERANGE;
+		}
 		return err;
 	}
 
-- 
2.21.0