Applied "spi: Check presence the of ->transfer[_xxx]() before registering a controller" to the spi tree

Mark Brown broonie at
Mon Apr 16 05:13:24 PDT 2018

The patch

   spi: Check presence the of ->transfer[_xxx]() before registering a controller

has been applied to the spi tree at 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

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>From bd40560ac3365e3a2d512d0ad03ceb6c7f603c0c Mon Sep 17 00:00:00 2001
From: Boris Brezillon <boris.brezillon at>
Date: Wed, 11 Apr 2018 00:44:30 +0200
Subject: [PATCH] spi: Check presence the of ->transfer[_xxx]() before
 registering a controller

Right now, no checks are done on the presence of a ->transfer[_xxx]()
method, which can lead to a NULL pointer dereference when someone
starts sending something on the bus.

Do the check at registration time and refuse to add the controller if
all ->transfer[_xxx]() pointers are NULL.

Signed-off-by: Boris Brezillon <boris.brezillon at>
Signed-off-by: Mark Brown <broonie at>
 drivers/spi/spi.c | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 7b213faa0a2b..24369e437c6b 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2063,6 +2063,19 @@ static int of_spi_register_master(struct spi_controller *ctlr)
+static int spi_controller_check_ops(struct spi_controller *ctlr)
+	/*
+	 * The controller must at least implement one of the ->transfer()
+	 * hooks.
+	 */
+	if (!ctlr->transfer && !ctlr->transfer_one &&
+	    !ctlr->transfer_one_message)
+		return -EINVAL;
+	return 0;
  * spi_register_controller - register SPI master or slave controller
  * @ctlr: initialized master, originally from spi_alloc_master() or
@@ -2096,6 +2109,14 @@ int spi_register_controller(struct spi_controller *ctlr)
 	if (!dev)
 		return -ENODEV;
+	/*
+	 * Make sure all necessary hooks are implemented before registering
+	 * the SPI controller.
+	 */
+	status = spi_controller_check_ops(ctlr);
+	if (status)
+		return status;
 	if (!spi_controller_is_slave(ctlr)) {
 		status = of_spi_register_master(ctlr);
 		if (status)

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