2021-07-25 12:49:38

by Benjamin Coddington

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

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 <[email protected]>
---
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

2021-07-26 13:34:17

by Benjamin Coddington

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

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 <[email protected]>
---
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

2021-07-26 14:43:02

by Chuck Lever

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

Hi Ben-

> On Jul 26, 2021, at 9:33 AM, Benjamin Coddington <[email protected]> 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 <[email protected]>

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