can: j1939: j1939_session_deactivate(): clarify lifetime of session object
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: 9d71dd0c ("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>
parent
54f93336