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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Date: Wed, 1 Jun 2022 19:51:59 +0900
Subject: [PATCH] bus: fsl-mc-bus: fix KASAN use-after-free in
fsl_mc_bus_remove()
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@vger.kernel.org # v5.15+
Signed-off-by: Shin'ichiro Kawasaki <shinichiro.kawasaki@wdc.com>
Link: https://lore.kernel.org/r/20220601105159.87752-1-shinichiro.kawasaki@wdc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
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 8fd4a356a86ec0b1cff2b830c6c1bf78924682f0..74593a1722fe0898fffbf19eb34673b10bd64ca3 100644
--- a/drivers/bus/fsl-mc/fsl-mc-bus.c
+++ b/drivers/bus/fsl-mc/fsl-mc-bus.c
@@ -1236,14 +1236,14 @@ 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);
bus_unregister_notifier(&fsl_mc_bus_type, &fsl_mc_nb);
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