ceph: fix recursion between ceph_set_acl() and __ceph_setattr()

ceph_set_acl() calls __ceph_setattr() if the setacl operation needs to modify inode's i_mode. __ceph_setattr() updates inode's i_mode, then calls posix_acl_chmod(). The problem is that __ceph_setattr() calls posix_acl_chmod() before sending the setattr request. The get_acl() call in posix_acl_chmod() can trigger a getxattr request. The reply of the getxattr request can restore inode's i_mode to its old value. The set_acl() call in posix_acl_chmod() sees old value of inode's i_mode, so it calls __ceph_setattr() again. Cc: [email protected] # needs backporting for < 4.9 Link: http://tracker.ceph.com/issues/19688 Reported-by: Jerry Lee <[email protected]> Signed-off-by: "Yan, Zheng" <[email protected]> Reviewed-by: Jeff Layton <[email protected]> Tested-by: Luis Henriques <[email protected]> Signed-off-by: Ilya Dryomov <[email protected]>
CamonZ · Apr 25, 2017 · 8179a10 · 8179a10
1 parent 5a7ad11
commit 8179a10
Showing 1 changed file with 10 additions and 12 deletions.
diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
@@ -2071,11 +2071,6 @@ int __ceph_setattr(struct inode *inode, struct iattr *attr)
 	if (inode_dirty_flags)
 		__mark_inode_dirty(inode, inode_dirty_flags);
 
-	if (ia_valid & ATTR_MODE) {
-		err = posix_acl_chmod(inode, attr->ia_mode);
-		if (err)
-			goto out_put;
-	}
 
 	if (mask) {
 		req->r_inode = inode;
@@ -2088,14 +2083,12 @@ int __ceph_setattr(struct inode *inode, struct iattr *attr)
 	dout("setattr %p result=%d (%s locally, %d remote)\n", inode, err,
 	     ceph_cap_string(dirtied), mask);
 
-	ceph_mdsc_put_request(req);
-	if (mask & CEPH_SETATTR_SIZE)
-		__ceph_do_pending_vmtruncate(inode);
-	ceph_free_cap_flush(prealloc_cf);
-	return err;
-out_put:
 	ceph_mdsc_put_request(req);
 	ceph_free_cap_flush(prealloc_cf);
+
+	if (err >= 0 && (mask & CEPH_SETATTR_SIZE))
+		__ceph_do_pending_vmtruncate(inode);
+
 	return err;
 }
 
@@ -2114,7 +2107,12 @@ int ceph_setattr(struct dentry *dentry, struct iattr *attr)
 	if (err != 0)
 		return err;
 
-	return __ceph_setattr(inode, attr);
+	err = __ceph_setattr(inode, attr);
+
+	if (err >= 0 && (attr->ia_valid & ATTR_MODE))
+		err = posix_acl_chmod(inode, attr->ia_mode);
+
+	return err;
 }
 
 /*