diff options
| author | Oleksij Rempel <o.rempel@pengutronix.de> | 2021-07-14 13:16:02 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-08-04 12:46:45 +0200 |
| commit | 55dd22c5d029423f513fd849e633adf0e9c10d0c (patch) | |
| tree | b13573b00ad4f454e8950fd9195ce22130270636 | |
| parent | 75ebe1d355b5b179568009ef35042d3c7be7ee00 (diff) | |
can: j1939: j1939_session_deactivate(): clarify lifetime of session object
commit 0c71437dd50dd687c15d8ca80b3b68f10bb21d63 upstream.
The j1939_session_deactivate() is decrementing the session ref-count and
potentially can free() the session. This would cause use-after-free
situation.
However, the code calling j1939_session_deactivate() does always hold
another reference to the session, so that it would not be free()ed in
this code path.
This patch adds a comment to make this clear and a WARN_ON, to ensure
that future changes will not violate this requirement. Further this
patch avoids dereferencing the session pointer as a precaution to avoid
use-after-free if the session is actually free()ed.
Fixes: 9d71dd0c7009 ("can: add support of SAE J1939 protocol")
Link: https://lore.kernel.org/r/20210714111602.24021-1-o.rempel@pengutronix.de
Reported-by: Xiaochen Zou <xzou017@ucr.edu>
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/can/j1939/transport.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c index 411322976950..bdc95bd7a851 100644 --- a/net/can/j1939/transport.c +++ b/net/can/j1939/transport.c @@ -1075,11 +1075,16 @@ static bool j1939_session_deactivate_locked(struct j1939_session *session) static bool j1939_session_deactivate(struct j1939_session *session) { + struct j1939_priv *priv = session->priv; bool active; - j1939_session_list_lock(session->priv); + j1939_session_list_lock(priv); + /* This function should be called with a session ref-count of at + * least 2. + */ + WARN_ON_ONCE(kref_read(&session->kref) < 2); active = j1939_session_deactivate_locked(session); - j1939_session_list_unlock(session->priv); + j1939_session_list_unlock(priv); return active; } |