This is a note to let you know that I've just added the patch titled
NLM: Defend against file_lock changes after vfs_test_lock()
to the 5.10-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:
nlm-defend-against-file_lock-changes-after-vfs_test_.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 877d7800645a18f7ee72a0a202cf5d940af224b7
Author: Benjamin Coddington <bcodding@xxxxxxxxxx>
Date: Mon Jun 13 09:40:06 2022 -0400
NLM: Defend against file_lock changes after vfs_test_lock()
[ Upstream commit 184cefbe62627730c30282df12bcff9aae4816ea ]
Instead of trusting that struct file_lock returns completely unchanged
after vfs_test_lock() when there's no conflicting lock, stash away our
nlm_lockowner reference so we can properly release it for all cases.
This defends against another file_lock implementation overwriting fl_owner
when the return type is F_UNLCK.
Reported-by: Roberto Bergantinos Corpas <rbergant@xxxxxxxxxx>
Tested-by: Roberto Bergantinos Corpas <rbergant@xxxxxxxxxx>
Signed-off-by: Benjamin Coddington <bcodding@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/lockd/svc4proc.c b/fs/lockd/svc4proc.c
index 176b468a61c75..4f247ab8be611 100644
--- a/fs/lockd/svc4proc.c
+++ b/fs/lockd/svc4proc.c
@@ -87,6 +87,7 @@ __nlm4svc_proc_test(struct svc_rqst *rqstp, struct nlm_res *resp)
struct nlm_args *argp = rqstp->rq_argp;
struct nlm_host *host;
struct nlm_file *file;
+ struct nlm_lockowner *test_owner;
__be32 rc = rpc_success;
dprintk("lockd: TEST4 called\n");
@@ -96,6 +97,7 @@ __nlm4svc_proc_test(struct svc_rqst *rqstp, struct nlm_res *resp)
if ((resp->status = nlm4svc_retrieve_args(rqstp, argp, &host, &file)))
return resp->status == nlm_drop_reply ? rpc_drop_reply :rpc_success;
+ test_owner = argp->lock.fl.fl_owner;
/* Now check for conflicting locks */
resp->status = nlmsvc_testlock(rqstp, file, host, &argp->lock, &resp->lock, &resp->cookie);
if (resp->status == nlm_drop_reply)
@@ -103,7 +105,7 @@ __nlm4svc_proc_test(struct svc_rqst *rqstp, struct nlm_res *resp)
else
dprintk("lockd: TEST4 status %d\n", ntohl(resp->status));
- nlmsvc_release_lockowner(&argp->lock);
+ nlmsvc_put_lockowner(test_owner);
nlmsvc_release_host(host);
nlm_release_file(file);
return rc;
diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index cb3658ab9b7ae..9c1aa75441e1c 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -340,7 +340,7 @@ nlmsvc_get_lockowner(struct nlm_lockowner *lockowner)
return lockowner;
}
-static void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
+void nlmsvc_put_lockowner(struct nlm_lockowner *lockowner)
{
if (!refcount_dec_and_lock(&lockowner->count, &lockowner->host->h_lock))
return;
@@ -590,7 +590,6 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
int error;
int mode;
__be32 ret;
- struct nlm_lockowner *test_owner;
dprintk("lockd: nlmsvc_testlock(%s/%ld, ty=%d, %Ld-%Ld)\n",
nlmsvc_file_inode(file)->i_sb->s_id,
@@ -604,9 +603,6 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
goto out;
}
- /* If there's a conflicting lock, remember to clean up the test lock */
- test_owner = (struct nlm_lockowner *)lock->fl.fl_owner;
-
mode = lock_to_openmode(&lock->fl);
error = vfs_test_lock(file->f_file[mode], &lock->fl);
if (error) {
@@ -635,10 +631,6 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
conflock->fl.fl_end = lock->fl.fl_end;
locks_release_private(&lock->fl);
- /* Clean up the test lock */
- lock->fl.fl_owner = NULL;
- nlmsvc_put_lockowner(test_owner);
-
ret = nlm_lck_denied;
out:
return ret;
diff --git a/fs/lockd/svcproc.c b/fs/lockd/svcproc.c
index 4dc1b40a489a2..b09ca35b527cc 100644
--- a/fs/lockd/svcproc.c
+++ b/fs/lockd/svcproc.c
@@ -116,6 +116,7 @@ __nlmsvc_proc_test(struct svc_rqst *rqstp, struct nlm_res *resp)
struct nlm_args *argp = rqstp->rq_argp;
struct nlm_host *host;
struct nlm_file *file;
+ struct nlm_lockowner *test_owner;
__be32 rc = rpc_success;
dprintk("lockd: TEST called\n");
@@ -125,6 +126,8 @@ __nlmsvc_proc_test(struct svc_rqst *rqstp, struct nlm_res *resp)
if ((resp->status = nlmsvc_retrieve_args(rqstp, argp, &host, &file)))
return resp->status == nlm_drop_reply ? rpc_drop_reply :rpc_success;
+ test_owner = argp->lock.fl.fl_owner;
+
/* Now check for conflicting locks */
resp->status = cast_status(nlmsvc_testlock(rqstp, file, host, &argp->lock, &resp->lock, &resp->cookie));
if (resp->status == nlm_drop_reply)
@@ -133,7 +136,7 @@ __nlmsvc_proc_test(struct svc_rqst *rqstp, struct nlm_res *resp)
dprintk("lockd: TEST status %d vers %d\n",
ntohl(resp->status), rqstp->rq_vers);
- nlmsvc_release_lockowner(&argp->lock);
+ nlmsvc_put_lockowner(test_owner);
nlmsvc_release_host(host);
nlm_release_file(file);
return rc;
diff --git a/include/linux/lockd/lockd.h b/include/linux/lockd/lockd.h
index fcef192e5e45e..70ce419e27093 100644
--- a/include/linux/lockd/lockd.h
+++ b/include/linux/lockd/lockd.h
@@ -292,6 +292,7 @@ void nlmsvc_locks_init_private(struct file_lock *, struct nlm_host *, pid_t);
__be32 nlm_lookup_file(struct svc_rqst *, struct nlm_file **,
struct nlm_lock *);
void nlm_release_file(struct nlm_file *);
+void nlmsvc_put_lockowner(struct nlm_lockowner *);
void nlmsvc_release_lockowner(struct nlm_lock *);
void nlmsvc_mark_resources(struct net *);
void nlmsvc_free_host_resources(struct nlm_host *);
