linux-kernel - [PATCH 5.10 145/154] scsi: ufs: core: Fix task management completion timeout race

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Date:   Wed, 24 Nov 2021 12:59:01 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Bart Van Assche <bvanassche@....org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Subject: [PATCH 5.10 145/154] scsi: ufs: core: Fix task management completion timeout race

From: Adrian Hunter <adrian.hunter@...el.com>

commit 886fe2915cce6658b0fc19e64b82879325de61ea upstream.

__ufshcd_issue_tm_cmd() clears req->end_io_data after timing out, which
races with the completion function ufshcd_tmc_handler() which expects
req->end_io_data to have a value.

Note __ufshcd_issue_tm_cmd() and ufshcd_tmc_handler() are already
synchronized using hba->tmf_rqs and hba->outstanding_tasks under the
host_lock spinlock.

It is also not necessary (nor typical) to clear req->end_io_data because
the block layer does it before allocating out requests e.g. via
blk_get_request().

So fix by not clearing it.

Link: https://lore.kernel.org/r/20211108064815.569494-2-adrian.hunter@intel.com
Fixes: f5ef336fd2e4 ("scsi: ufs: core: Fix task management completion")
Reviewed-by: Bart Van Assche <bvanassche@....org>
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
[Adrian: Backport to v5.10]
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/scsi/ufs/ufshcd.c |    5 -----
 1 file changed, 5 deletions(-)

--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -6280,11 +6280,6 @@ static int __ufshcd_issue_tm_cmd(struct
 	err = wait_for_completion_io_timeout(&wait,
 			msecs_to_jiffies(TM_CMD_TIMEOUT));
 	if (!err) {
-		/*
-		 * Make sure that ufshcd_compl_tm() does not trigger a
-		 * use-after-free.
-		 */
-		req->end_io_data = NULL;
 		ufshcd_add_tm_upiu_trace(hba, task_tag, "tm_complete_err");
 		dev_err(hba->dev, "%s: task management cmd 0x%.2x timed-out\n",
 				__func__, tm_function);