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SubjectApplied "spi: fix use-after-free at controller deregistration" to the spi tree
The patch

spi: fix use-after-free at controller deregistration

has been applied to the spi tree at


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From 67f7b2781fafcc0f52464880154b320fea1ae982 Mon Sep 17 00:00:00 2001
From: Johan Hovold <>
Date: Mon, 30 Oct 2017 11:35:25 +0100
Subject: [PATCH] spi: fix use-after-free at controller deregistration

The controller is typically freed as part of device_unregister() so
store the bus id before deregistration to avoid use-after-free when the
id is later released.

Fixes: 9b61e302210e ("spi: Pick spi bus number from Linux idr or spi alias")
Signed-off-by: Johan Hovold <>
Signed-off-by: Mark Brown <>
Cc: stable <>
drivers/spi/spi.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 6e65524cbfd9..759c9725495a 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2240,11 +2240,12 @@ static int __unregister(struct device *dev, void *null)
void spi_unregister_controller(struct spi_controller *ctlr)
struct spi_controller *found;
+ int id = ctlr->bus_num;
int dummy;

/* First make sure that this controller was ever added */
- found = idr_find(&spi_master_idr, ctlr->bus_num);
+ found = idr_find(&spi_master_idr, id);
if (found != ctlr) {
@@ -2264,7 +2265,7 @@ void spi_unregister_controller(struct spi_controller *ctlr)
/* free bus id */
- idr_remove(&spi_master_idr, ctlr->bus_num);
+ idr_remove(&spi_master_idr, id);
 \ /
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