linux-kernel - [PATCH] firewire: net: fix unexpected release of object for asynchronous request packet

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Message-Id: <20230510031205.782032-1-o-takashi@sakamocchi.jp>
Date:   Wed, 10 May 2023 12:12:05 +0900
From:   Takashi Sakamoto <o-takashi@...amocchi.jp>
To:     linux1394-devel@...ts.sourceforge.net, linux-kernel@...r.kernel.org
Cc:     Dan Carpenter <error27@...il.com>
Subject: [PATCH] firewire: net: fix unexpected release of object for asynchronous request packet

The lifetime of object for asynchronous request packet is now maintained
by reference counting, while current implementation of firewire-net
releases the passed object in the handler.

This commit fixes the bug.

Reported-by: Dan Carpenter <error27@...il.com>
Link: https://lore.kernel.org/lkml/Y%2Fymx6WZIAlrtjLc@workstation/
Fixes: 13a55d6bb15f ("firewire: core: use kref structure to maintain lifetime of data for fw_request structure")
Signed-off-by: Takashi Sakamoto <o-takashi@...amocchi.jp>
---
 drivers/firewire/net.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/drivers/firewire/net.c b/drivers/firewire/net.c
index af22be84034b..538bd677c254 100644
--- a/drivers/firewire/net.c
+++ b/drivers/firewire/net.c
@@ -706,21 +706,22 @@ static void fwnet_receive_packet(struct fw_card *card, struct fw_request *r,
 	int rcode;
 
 	if (destination == IEEE1394_ALL_NODES) {
-		kfree(r);
-
-		return;
-	}
-
-	if (offset != dev->handler.offset)
+		// Although the response to the broadcast packet is not necessarily required, the
+		// fw_send_response() function should still be called to maintain the reference
+		// counting of the object. In the case, the call of function just releases the
+		// object as a result to decrease the reference counting.
+		rcode = RCODE_COMPLETE;
+	} else if (offset != dev->handler.offset) {
 		rcode = RCODE_ADDRESS_ERROR;
-	else if (tcode != TCODE_WRITE_BLOCK_REQUEST)
+	} else if (tcode != TCODE_WRITE_BLOCK_REQUEST) {
 		rcode = RCODE_TYPE_ERROR;
-	else if (fwnet_incoming_packet(dev, payload, length,
-				       source, generation, false) != 0) {
+	} else if (fwnet_incoming_packet(dev, payload, length,
+					 source, generation, false) != 0) {
 		dev_err(&dev->netdev->dev, "incoming packet failure\n");
 		rcode = RCODE_CONFLICT_ERROR;
-	} else
+	} else {
 		rcode = RCODE_COMPLETE;
+	}
 
 	fw_send_response(card, r, rcode);
 }
-- 
2.37.2