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spi: Fix null dereference on suspend

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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@chromium.org>
Link: https://lore.kernel.org/r/20231107144743.v1.1.I7987f05f61901f567f7661763646cb7d7919b528@changeid
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@kernel.org
This commit is contained in:
Mark Hasemeyer 2023-11-07 14:47:43 -07:00 committed by Mark Brown
parent c2ded280a4
commit bef4a48f4e
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
2 changed files with 40 additions and 17 deletions
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56
drivers/spi/spi.c
View File

@ -3317,33 +3317,52 @@ 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;
int ret = 0;
if (!ctlr->queued)
return 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);
@ -4147,8 +4166,7 @@ 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;
@ -4164,7 +4182,6 @@ static void __spi_transfer_message_noqueue(struct spi_controller *ctlr, struct s
spi_idle_runtime_pm(ctlr);
}
out:
mutex_unlock(&ctlr->io_mutex);
}
@ -4187,6 +4204,11 @@ 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;

1
include/linux/spi/spi.h
View File

@ -566,6 +566,7 @@ struct spi_controller {
#define SPI_CONTROLLER_MUST_RX BIT(3) /* Requires rx */
#define SPI_CONTROLLER_MUST_TX BIT(4) /* Requires tx */
#define SPI_CONTROLLER_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;