linux-kernel - [PATCH v5.10.y] bus: fsl-mc-bus: fix KASAN use-after-free in fsl_mc_bus

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Message-ID: <20251223074625.1428715-1-keerthana.kalyanasundaram@broadcom.com>
Date: Tue, 23 Dec 2025 07:46:25 +0000
From: Keerthana K <keerthana.kalyanasundaram@...adcom.com>
To: stable@...r.kernel.org,
	gregkh@...uxfoundation.org
Cc: stuyoder@...il.com,
	laurentiu.tudor@....com,
	Bharat.Bhushan@....com,
	linux-kernel@...r.kernel.org,
	ajay.kaher@...adcom.com,
	alexey.makhalov@...adcom.com,
	vamsi-krishna.brahmajosyula@...adcom.com,
	yin.ding@...adcom.com,
	tapas.kundu@...adcom.com,
	Shin'ichiro Kawasaki <shinichiro.kawasaki@....com>,
	Keerthana K <keerthana.kalyanasundaram@...adcom.com>
Subject: [PATCH v5.10.y] bus: fsl-mc-bus: fix KASAN use-after-free in fsl_mc_bus_remove()

From: Shin'ichiro Kawasaki <shinichiro.kawasaki@....com>

commit 928ea98252ad75118950941683893cf904541da9 upstream.

In fsl_mc_bus_remove(), mc->root_mc_bus_dev->mc_io is passed to
fsl_destroy_mc_io(). However, mc->root_mc_bus_dev is already freed in
fsl_mc_device_remove(). Then reference to mc->root_mc_bus_dev->mc_io
triggers KASAN use-after-free. To avoid the use-after-free, keep the
reference to mc->root_mc_bus_dev->mc_io in a local variable and pass to
fsl_destroy_mc_io().

This patch needs rework to apply to kernels older than v5.15.

Fixes: f93627146f0e ("staging: fsl-mc: fix asymmetry in destroy of mc_io")
Cc: stable@...r.kernel.org # v5.15+
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@....com>
Link: https://lore.kernel.org/r/20220601105159.87752-1-shinichiro.kawasaki@wdc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
[ Keerthana: Backported the patch to v5.10.y ]
Signed-off-by: Keerthana K <keerthana.kalyanasundaram@...adcom.com>
---
 drivers/bus/fsl-mc/fsl-mc-bus.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/bus/fsl-mc/fsl-mc-bus.c b/drivers/bus/fsl-mc/fsl-mc-bus.c
index dd7791f48537..4f13e7d8101b 100644
--- a/drivers/bus/fsl-mc/fsl-mc-bus.c
+++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
@@ -1085,14 +1085,14 @@ static int fsl_mc_bus_probe(struct platform_device *pdev)
 static int fsl_mc_bus_remove(struct platform_device *pdev)
 {
 	struct fsl_mc *mc = platform_get_drvdata(pdev);
+	struct fsl_mc_io *mc_io;
 
 	if (!fsl_mc_is_root_dprc(&mc->root_mc_bus_dev->dev))
 		return -EINVAL;
 
+	mc_io = mc->root_mc_bus_dev->mc_io;
 	fsl_mc_device_remove(mc->root_mc_bus_dev);
-
-	fsl_destroy_mc_io(mc->root_mc_bus_dev->mc_io);
-	mc->root_mc_bus_dev->mc_io = NULL;
+	fsl_destroy_mc_io(mc_io);
 
 	return 0;
 }
-- 
2.43.7