6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mark Hasemeyer <markhas@xxxxxxxxxxxx> [ Upstream commit bef4a48f4ef798c4feddf045d49e53c8a97d5e37 ] A race condition exists where a synchronous (noqueue) transfer can be active during a system suspend. This can cause a null pointer dereference exception to occur when the system resumes. Example order of events leading to the exception: 1. spi_sync() calls __spi_transfer_message_noqueue() which sets ctlr->cur_msg 2. Spi transfer begins via spi_transfer_one_message() 3. System is suspended interrupting the transfer context 4. System is resumed 6. spi_controller_resume() calls spi_start_queue() which resets cur_msg to NULL 7. Spi transfer context resumes and spi_finalize_current_message() is called which dereferences cur_msg (which is now NULL) Wait for synchronous transfers to complete before suspending by acquiring the bus mutex and setting/checking a suspend flag. Signed-off-by: Mark Hasemeyer <markhas@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/20231107144743.v1.1.I7987f05f61901f567f7661763646cb7d7919b528@changeid Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> Cc: stable@xxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/spi/spi.c | 56 ++++++++++++++++++++++++++++------------- include/linux/spi/spi.h | 1 + 2 files changed, 40 insertions(+), 17 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 151fef199c380..5d046be8b2dd5 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -3299,33 +3299,52 @@ void spi_unregister_controller(struct spi_controller *ctlr) } EXPORT_SYMBOL_GPL(spi_unregister_controller); +static inline int __spi_check_suspended(const struct spi_controller *ctlr) +{ + return ctlr->flags & SPI_CONTROLLER_SUSPENDED ? -ESHUTDOWN : 0; +} + +static inline void __spi_mark_suspended(struct spi_controller *ctlr) +{ + mutex_lock(&ctlr->bus_lock_mutex); + ctlr->flags |= SPI_CONTROLLER_SUSPENDED; + mutex_unlock(&ctlr->bus_lock_mutex); +} + +static inline void __spi_mark_resumed(struct spi_controller *ctlr) +{ + mutex_lock(&ctlr->bus_lock_mutex); + ctlr->flags &= ~SPI_CONTROLLER_SUSPENDED; + mutex_unlock(&ctlr->bus_lock_mutex); +} + int spi_controller_suspend(struct spi_controller *ctlr) { - int ret; + int ret = 0; /* Basically no-ops for non-queued controllers */ - if (!ctlr->queued) - return 0; - - ret = spi_stop_queue(ctlr); - if (ret) - dev_err(&ctlr->dev, "queue stop failed\n"); + if (ctlr->queued) { + ret = spi_stop_queue(ctlr); + if (ret) + dev_err(&ctlr->dev, "queue stop failed\n"); + } + __spi_mark_suspended(ctlr); return ret; } EXPORT_SYMBOL_GPL(spi_controller_suspend); int spi_controller_resume(struct spi_controller *ctlr) { - int ret; - - if (!ctlr->queued) - return 0; + int ret = 0; - ret = spi_start_queue(ctlr); - if (ret) - dev_err(&ctlr->dev, "queue restart failed\n"); + __spi_mark_resumed(ctlr); + if (ctlr->queued) { + ret = spi_start_queue(ctlr); + if (ret) + dev_err(&ctlr->dev, "queue restart failed\n"); + } return ret; } EXPORT_SYMBOL_GPL(spi_controller_resume); @@ -4050,8 +4069,7 @@ static void __spi_transfer_message_noqueue(struct spi_controller *ctlr, struct s ctlr->cur_msg = msg; ret = __spi_pump_transfer_message(ctlr, msg, was_busy); if (ret) - goto out; - + dev_err(&ctlr->dev, "noqueue transfer failed\n"); ctlr->cur_msg = NULL; ctlr->fallback = false; @@ -4067,7 +4085,6 @@ static void __spi_transfer_message_noqueue(struct spi_controller *ctlr, struct s spi_idle_runtime_pm(ctlr); } -out: mutex_unlock(&ctlr->io_mutex); } @@ -4090,6 +4107,11 @@ static int __spi_sync(struct spi_device *spi, struct spi_message *message) int status; struct spi_controller *ctlr = spi->controller; + if (__spi_check_suspended(ctlr)) { + dev_warn_once(&spi->dev, "Attempted to sync while suspend\n"); + return -ESHUTDOWN; + } + status = __spi_validate(spi, message); if (status != 0) return status; diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index fbf8c0d95968e..877395e075afe 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -531,6 +531,7 @@ struct spi_controller { #define SPI_CONTROLLER_MUST_TX BIT(4) /* Requires tx */ #define SPI_MASTER_GPIO_SS BIT(5) /* GPIO CS must select slave */ +#define SPI_CONTROLLER_SUSPENDED BIT(6) /* Currently suspended */ /* Flag indicating if the allocation of this struct is devres-managed */ bool devm_allocated; -- 2.42.0
