linux-brain/net/can/j1939
Oleksij Rempel 7eef18c047 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: 9d71dd0c70 ("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>
2021-08-04 12:27:40 +02:00
..
Kconfig can: add support of SAE J1939 protocol 2019-09-04 14:22:33 +02:00
Makefile can: add support of SAE J1939 protocol 2019-09-04 14:22:33 +02:00
address-claim.c can: add support of SAE J1939 protocol 2019-09-04 14:22:33 +02:00
bus.c can: add support of SAE J1939 protocol 2019-09-04 14:22:33 +02:00
j1939-priv.h can: add support of SAE J1939 protocol 2019-09-04 14:22:33 +02:00
main.c can: j1939: j1939_sk_init(): set SOCK_RCU_FREE to call sk_destruct() after RCU is done 2021-07-14 16:53:04 +02:00
socket.c can: j1939: j1939_sk_init(): set SOCK_RCU_FREE to call sk_destruct() after RCU is done 2021-07-14 16:53:04 +02:00
transport.c can: j1939: j1939_session_deactivate(): clarify lifetime of session object 2021-08-04 12:27:40 +02:00