[PATCH] can: bcm: fix locking for bcm_op runtime updates

[Oliver Hartkopp via B4 Relay]

From: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>

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@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/linux-can/699466e4.a70a0220.2c38d7.00ff.GAE@xxxxxxxxxx/
Signed-off-by: Oliver Hartkopp <socketcan@xxxxxxxxxxxx>
---
 net/can/bcm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/can/bcm.c b/net/can/bcm.c
index b7324e9c955b..fd9fa072881e 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -1174,10 +1174,11 @@ static int bcm_rx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg,
 		/* insert new BCM operation for the given can_id */
 		op = kzalloc(OPSIZ, GFP_KERNEL);
 		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);
 		op->flags = msg_head->flags;
 

---
base-commit: 2961f841b025fb234860bac26dfb7fa7cb0fb122
change-id: 20260218-bcm_spin_lock_init-2518eb8d4501

Best regards,
--  
Oliver Hartkopp <socketcan@xxxxxxxxxxxx>