Patch "ceph: fix recursion between ceph_set_acl() and __ceph_setattr()" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

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

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     ceph-fix-recursion-between-ceph_set_acl-and-__ceph_setattr.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 8179a101eb5f4ef0ac9a915fcea9a9d3109efa90 Mon Sep 17 00:00:00 2001
From: "Yan, Zheng" <zyan@redhat.com>
Date: Wed, 19 Apr 2017 10:01:48 +0800
Subject: ceph: fix recursion between ceph_set_acl() and __ceph_setattr()

From: Yan, Zheng <zyan@redhat.com>

commit 8179a101eb5f4ef0ac9a915fcea9a9d3109efa90 upstream.

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: stable@vger.kernel.org # needs backporting for < 4.9
Link: http://tracker.ceph.com/issues/19688
Reported-by: Jerry Lee <leisurelysw24@gmail.com>
Signed-off-by: "Yan, Zheng" <zyan@redhat.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Tested-by: Luis Henriques <lhenriques@suse.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
[luis: introduce __ceph_setattr() and make ceph_set_acl() call it, as
 suggested by Yan.]
Signed-off-by: Luis Henriques <lhenriques@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: “Yan, Zheng” <zyan@redhat.com>
---
 fs/ceph/acl.c   |    4 ++--
 fs/ceph/inode.c |   27 ++++++++++++++++-----------
 fs/ceph/super.h |    1 +
 3 files changed, 19 insertions(+), 13 deletions(-)

--- a/fs/ceph/acl.c
+++ b/fs/ceph/acl.c
@@ -128,7 +128,7 @@ int ceph_set_acl(struct inode *inode, st
 	if (new_mode != old_mode) {
 		newattrs.ia_mode = new_mode;
 		newattrs.ia_valid = ATTR_MODE;
-		ret = ceph_setattr(dentry, &newattrs);
+		ret = __ceph_setattr(dentry, &newattrs);
 		if (ret)
 			goto out_dput;
 	}
@@ -138,7 +138,7 @@ int ceph_set_acl(struct inode *inode, st
 		if (new_mode != old_mode) {
 			newattrs.ia_mode = old_mode;
 			newattrs.ia_valid = ATTR_MODE;
-			ceph_setattr(dentry, &newattrs);
+			__ceph_setattr(dentry, &newattrs);
 		}
 		goto out_dput;
 	}
--- a/fs/ceph/inode.c
+++ b/fs/ceph/inode.c
@@ -1773,7 +1773,7 @@ static const struct inode_operations cep
 /*
  * setattr
  */
-int ceph_setattr(struct dentry *dentry, struct iattr *attr)
+int __ceph_setattr(struct dentry *dentry, struct iattr *attr)
 {
 	struct inode *inode = d_inode(dentry);
 	struct ceph_inode_info *ci = ceph_inode(inode);
@@ -1975,11 +1975,6 @@ int ceph_setattr(struct dentry *dentry,
 	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;
@@ -1993,13 +1988,23 @@ int ceph_setattr(struct dentry *dentry,
 	     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);
+
+	if (err >= 0 && (mask & CEPH_SETATTR_SIZE))
+		__ceph_do_pending_vmtruncate(inode);
+
 	return err;
-out_put:
-	ceph_mdsc_put_request(req);
-	ceph_free_cap_flush(prealloc_cf);
+}
+
+int ceph_setattr(struct dentry *dentry, struct iattr *attr)
+{
+	int err;
+
+	err = __ceph_setattr(dentry, attr);
+
+	if (err >= 0 && (attr->ia_valid & ATTR_MODE))
+		err = posix_acl_chmod(d_inode(dentry), attr->ia_mode);
+
 	return err;
 }
 
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -788,6 +788,7 @@ static inline int ceph_do_getattr(struct
 	return __ceph_do_getattr(inode, NULL, mask, force);
 }
 extern int ceph_permission(struct inode *inode, int mask);
+extern int __ceph_setattr(struct dentry *dentry, struct iattr *attr);
 extern int ceph_setattr(struct dentry *dentry, struct iattr *attr);
 extern int ceph_getattr(struct vfsmount *mnt, struct dentry *dentry,
 			struct kstat *stat);


Patches currently in stable-queue which might be from zyan@redhat.com are

queue-4.4/ceph-fix-recursion-between-ceph_set_acl-and-__ceph_setattr.patch