[PATCH 6.12 193/265] can: bcm: fix locking for bcm_op runtime updates

Greg Kroah-Hartman
2026-03-12T20:26:17Z

From: Oliver Hartkopp <socketcan@hartkopp.net>

[ Upstream commit c35636e91e392e1540949bbc67932167cb48bc3a ]

Commit c2aba69d0c36 ("can: bcm: add locking for bcm_op runtime updates")
added a locking for some variables that can be modified at runtime when
updating the sending bcm_op with a new TX_SETUP command in bcm_tx_setup().

Usually the RX_SETUP only handles and filters incoming traffic with one
exception: When the RX_RTR_FRAME flag is set a predefined CAN frame is
sent when a specific RTR frame is received. Therefore the rx bcm_op uses
bcm_can_tx() which uses the bcm_tx_lock that was only initialized in
bcm_tx_setup(). Add the missing spin_lock_init() when allocating the
bcm_op in bcm_rx_setup() to handle the RTR case properly.

Fixes: c2aba69d0c36 ("can: bcm: add locking for bcm_op runtime updates")
Reported-by: syzbot+5b11eccc403dd1cea9f8@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-can/699466e4.a70a0220.2c38d7.00ff.GAE@google.com/
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://patch.msgid.link/20260218-bcm_spin_lock_init-v1-1-592634c8a5b5@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/can/bcm.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/net/can/bcm.c b/net/can/bcm.c
index e33ff2a5b20cc..152cc29e87d7a 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -1170,6 +1170,7 @@ static int bcm_rx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
if (!op)
return -ENOMEM;

+ spin_lock_init(&op->bcm_tx_lock);
op->can_id = msg_head->can_id;
op->nframes = msg_head->nframes;
op->cfsiz = CFSIZ(msg_head->flags);
--
2.51.0