linux-kernel - [PATCH 1/2] ceph/mds_client: transfer CEPH_CAP_PIN when updating r

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250901151448.726098-1-amarkuze@redhat.com>
Date: Mon,  1 Sep 2025 15:14:47 +0000
From: Alex Markuze <amarkuze@...hat.com>
To: ceph-devel@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	Slava.Dubeyko@....com,
	idryomov@...il.com,
	Alex Markuze <amarkuze@...hat.com>
Subject: [PATCH 1/2] ceph/mds_client: transfer CEPH_CAP_PIN when updating r_parent on mismatch

When the parent directory lock is not held, req->r_parent can become stale between dentry lookup and request encoding.
The client updates r_parent to the correct inode based on the encoded path, but previously did not adjust CEPH_CAP_PIN references.

Release the pin from the old parent and acquire it for the new parent when switching r_parent, ensuring reference accounting stays balanced and avoiding leaks or underflows later in ceph_mdsc_release_request().

Signed-off-by: Alex Markuze <amarkuze@...hat.com>
---
 fs/ceph/mds_client.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
index ce0c129f4651..4e5926f36e8d 100644
--- a/fs/ceph/mds_client.c
+++ b/fs/ceph/mds_client.c
@@ -3053,12 +3053,19 @@ static struct ceph_msg *create_request_message(struct ceph_mds_session *session,
 	 */
 	if (!parent_locked && req->r_parent && path_info1.vino.ino &&
 	    ceph_ino(req->r_parent) != path_info1.vino.ino) {
+		struct inode *old_parent = req->r_parent;
 		struct inode *correct_dir = ceph_get_inode(mdsc->fsc->sb, path_info1.vino, NULL);
 		if (!IS_ERR(correct_dir)) {
 			WARN_ONCE(1, "ceph: r_parent mismatch (had %llx wanted %llx) - updating\n",
-				  ceph_ino(req->r_parent), path_info1.vino.ino);
-			iput(req->r_parent);
+			          ceph_ino(old_parent), path_info1.vino.ino);
+			/*
+			 * Transfer CEPH_CAP_PIN from the old parent to the new one.
+			 * The pin was taken earlier in ceph_mdsc_submit_request().
+			 */
+			ceph_put_cap_refs(ceph_inode(old_parent), CEPH_CAP_PIN);
+			iput(old_parent);
 			req->r_parent = correct_dir;
+			ceph_get_cap_refs(ceph_inode(req->r_parent), CEPH_CAP_PIN);
 		}
 	}
 
-- 
2.34.1