From ff61eb422024a4614f898c1c73625e222b219a5d Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Tue, 7 Apr 2015 20:39:19 +0200 Subject: [PATCH] spi: Make master->handle_err() callback optional to avoid crashes If a driver doesn't implement the master->handle_err() callback and an SPI transfer fails, the kernel will crash with a NULL pointer dereference: Unable to handle kernel NULL pointer dereference at virtual address 00000000 pgd = c0003000 [00000000] *pgd=80000040004003, *pmd=00000000 Internal error: Oops: 80000206 [#1] SMP ARM Modules linked in: CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.0.0-rc7-koelsch-05861-g1fc9fdd4add4f783 #1046 Hardware name: Generic R8A7791 (Flattened Device Tree) task: eec359c0 ti: eec54000 task.ti: eec54000 PC is at 0x0 LR is at spi_transfer_one_message+0x1cc/0x1f0 Make the master->handle_err() callback optional to avoid the crash. Also fix a spelling mistake in the callback documentation while we're at it. Fixes: b716c4ffc6a2b0bf ("spi: introduce master->handle_err() callback") Signed-off-by: Geert Uytterhoeven Signed-off-by: Mark Brown --- drivers/spi/spi.c | 2 +- include/linux/spi/spi.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 31d4d9d..7713253 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -851,7 +851,7 @@ out: if (msg->status == -EINPROGRESS) msg->status = ret; - if (msg->status) + if (msg->status && master->handle_err) master->handle_err(master, msg); spi_finalize_current_message(master); diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 4eaac3a5..5685af8 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -294,7 +294,7 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) * transfer_one_message are mutually exclusive; when both * are set, the generic subsystem does not call your * transfer_one callback. - * @handle_err: the subsystem calls the driver to handle and error that occurs + * @handle_err: the subsystem calls the driver to handle an error that occurs * in the generic implementation of transfer_one_message(). * @unprepare_message: undo any work done by prepare_message(). * @cs_gpios: Array of GPIOs to use as chip select lines; one per CS -- 2.7.4