5.4-stable review patch. If anyone has any objections, please let me know.
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From: Wolfram Sang wsa+renesas@sang-engineering.com
[ Upstream commit e8d1b41e69d72c62865bebe8f441163ec00b3d44 ]
With the to-be-fixed commit, the reset_work handler cleared 'host->mrq' outside of the spinlock protected critical section. That leaves a small race window during execution of 'tmio_mmc_reset()' where the done_work handler could grab a pointer to the now invalid 'host->mrq'. Both would use it to call mmc_request_done() causing problems (see link below).
However, 'host->mrq' cannot simply be cleared earlier inside the critical section. That would allow new mrqs to come in asynchronously while the actual reset of the controller still needs to be done. So, like 'tmio_mmc_set_ios()', an ERR_PTR is used to prevent new mrqs from coming in but still avoiding concurrency between work handlers.
Reported-by: Dirk Behme dirk.behme@de.bosch.com Closes: https://lore.kernel.org/all/20240220061356.3001761-1-dirk.behme@de.bosch.com... Fixes: df3ef2d3c92c ("mmc: protect the tmio_mmc driver against a theoretical race") Signed-off-by: Wolfram Sang wsa+renesas@sang-engineering.com Tested-by: Dirk Behme dirk.behme@de.bosch.com Reviewed-by: Dirk Behme dirk.behme@de.bosch.com Cc: stable@vger.kernel.org # 3.0+ Link: https://lore.kernel.org/r/20240305104423.3177-2-wsa+renesas@sang-engineering... Signed-off-by: Ulf Hansson ulf.hansson@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/mmc/host/tmio_mmc_core.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/drivers/mmc/host/tmio_mmc_core.c b/drivers/mmc/host/tmio_mmc_core.c index 25083f010a7ad..e21907b92cf11 100644 --- a/drivers/mmc/host/tmio_mmc_core.c +++ b/drivers/mmc/host/tmio_mmc_core.c @@ -217,6 +217,8 @@ static void tmio_mmc_reset_work(struct work_struct *work) else mrq->cmd->error = -ETIMEDOUT;
+ /* No new calls yet, but disallow concurrent tmio_mmc_done_work() */ + host->mrq = ERR_PTR(-EBUSY); host->cmd = NULL; host->data = NULL;