From 842cf1ab756aaa5ee67ce2f0cc0f8925367e9760 Mon Sep 17 00:00:00 2001 From: Wolfram Sang Date: Tue, 5 Mar 2024 11:42:56 +0100 Subject: [PATCH] mmc: tmio: avoid concurrent runs of mmc_request_done() [ 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 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 Tested-by: Dirk Behme Reviewed-by: Dirk Behme Cc: stable@vger.kernel.org # 3.0+ Link: https://lore.kernel.org/r/20240305104423.3177-2-wsa+renesas@sang-engineering.com Signed-off-by: Ulf Hansson Signed-off-by: Sasha Levin --- 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 be7f18fd4836a..c253d176db691 100644 --- a/drivers/mmc/host/tmio_mmc_core.c +++ b/drivers/mmc/host/tmio_mmc_core.c @@ -259,6 +259,8 @@ 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;