[PATCH] lockd: Fix invalid lockowner cast after vfs_test_lock

[PATCH] lockd: Fix invalid lockowner cast after vfs_test_lock

[Benjamin Coddington]

After calling vfs_test_lock() the pointer to a conflicting lock can be
returned, and that lock is not garunteed to owned by nlm.  In that case, we
cannot cast it to struct nlm_lockowner.  Instead, return the pid of that
conflicting lock.

Fixes: 646d73e91b42 ("lockd: Show pid of lockd for remote locks")
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
---
 fs/lockd/svclock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index 61d3cc2283dc..498cb70c2c0d 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -634,7 +634,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 	conflock->caller = "somehost";	/* FIXME */
 	conflock->len = strlen(conflock->caller);
 	conflock->oh.len = 0;		/* don't return OH info */
-	conflock->svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid;
+	conflock->svid = lock->fl.fl_pid;
 	conflock->fl.fl_type = lock->fl.fl_type;
 	conflock->fl.fl_start = lock->fl.fl_start;
 	conflock->fl.fl_end = lock->fl.fl_end;
-- 
2.30.2

[PATCH V2] lockd: Fix invalid lockowner cast after vfs_test_lock

[Benjamin Coddington]

V2: fix typos in patch header

8<-------------------------------------------------------

After calling vfs_test_lock() the pointer to a conflicting lock can be
returned, and that lock is not guarunteed to be owned by nlm.  In that
case, we cannot cast it to struct nlm_lockowner.  Instead return the pid
of that conflicting lock.

Fixes: 646d73e91b42 ("lockd: Show pid of lockd for remote locks")
Signed-off-by: Benjamin Coddington <bcodding@redhat.com>
---
 fs/lockd/svclock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
index 61d3cc2283dc..498cb70c2c0d 100644
--- a/fs/lockd/svclock.c
+++ b/fs/lockd/svclock.c
@@ -634,7 +634,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
 	conflock->caller = "somehost";	/* FIXME */
 	conflock->len = strlen(conflock->caller);
 	conflock->oh.len = 0;		/* don't return OH info */
-	conflock->svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid;
+	conflock->svid = lock->fl.fl_pid;
 	conflock->fl.fl_type = lock->fl.fl_type;
 	conflock->fl.fl_start = lock->fl.fl_start;
 	conflock->fl.fl_end = lock->fl.fl_end;
-- 
2.30.2

Re: [PATCH V2] lockd: Fix invalid lockowner cast after vfs_test_lock

[Chuck Lever III]

Hi Ben-

> On Jul 26, 2021, at 9:33 AM, Benjamin Coddington <bcodding@redhat.com> wrote:
> 
> V2: fix typos in patch header
> 
> 8<-------------------------------------------------------
> 
> After calling vfs_test_lock() the pointer to a conflicting lock can be
> returned, and that lock is not guarunteed to be owned by nlm.  In that
> case, we cannot cast it to struct nlm_lockowner.  Instead return the pid
> of that conflicting lock.
> 
> Fixes: 646d73e91b42 ("lockd: Show pid of lockd for remote locks")
> Signed-off-by: Benjamin Coddington <bcodding@redhat.com>

I've added this change provisionally to

https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git/log/?h=for-next


> ---
> fs/lockd/svclock.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c
> index 61d3cc2283dc..498cb70c2c0d 100644
> --- a/fs/lockd/svclock.c
> +++ b/fs/lockd/svclock.c
> @@ -634,7 +634,7 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file,
> 	conflock->caller = "somehost";	/* FIXME */
> 	conflock->len = strlen(conflock->caller);
> 	conflock->oh.len = 0;		/* don't return OH info */
> -	conflock->svid = ((struct nlm_lockowner *)lock->fl.fl_owner)->pid;
> +	conflock->svid = lock->fl.fl_pid;
> 	conflock->fl.fl_type = lock->fl.fl_type;
> 	conflock->fl.fl_start = lock->fl.fl_start;
> 	conflock->fl.fl_end = lock->fl.fl_end;
> -- 
> 2.30.2
> 

--
Chuck Lever