scsi: ufs: core: Improve SCSI abort handling

From: Bart Van Assche <[email protected]>

commit 3ff1f6b6ba6f97f50862aa50e79959cc8ddc2566 upstream.

The following has been observed on a test setup:

WARNING: CPU: 4 PID: 250 at drivers/scsi/ufs/ufshcd.c:2737 ufshcd_queuecommand+0x468/0x65c
Call trace:
 ufshcd_queuecommand+0x468/0x65c
 scsi_send_eh_cmnd+0x224/0x6a0
 scsi_eh_test_devices+0x248/0x418
 scsi_eh_ready_devs+0xc34/0xe58
 scsi_error_handler+0x204/0x80c
 kthread+0x150/0x1b4
 ret_from_fork+0x10/0x30

That warning is triggered by the following statement:

	WARN_ON(lrbp->cmd);

Fix this warning by clearing lrbp->cmd from the abort handler.

[ kovalev: bp to fix CVE-2021-47188; adapted placement of
lrbp->cmd = NULL for 5.10 function structure ]

---
 drivers/scsi/ufs/ufshcd.c | 1 +
 1 file changed, 1 insertion(+)

index c7bf0e6bc303..1b8072f47e7e 100644
@@ -6788,6 +6788,7 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
 		__ufshcd_transfer_req_compl(hba, (1UL << tag));
 		spin_unlock_irqrestore(host->host_lock, flags);
 out:
+		lrbp->cmd = NULL;
 		err = SUCCESS;
 	} else {
 		dev_err(hba->dev, "%s: failed with err %d\n", __func__, err);

2.50.1

Hi Sasha,

Please drop this backport from the 5.10 queue — it is not needed.

After review feedback from Fedor Pchelkin, we verified that 5.10 is not affected by this bug. The upstream commit 3ff1f6b6ba6f carries an incorrect Fixes tag:

The actual regression was introduced by:

64180742605f ("scsi: ufs: Fix the SCSI abort handler") [v5.15-rc1]

which restructured ufshcd_abort() and removed the __ufshcd_transfer_req_compl() call from the successful abort path. Before that commit — and in 5.10 to this day — __ufshcd_transfer_req_compl() is always called on the successful path via the cleanup: label, and it clears lrbp->cmd. So the WARN_ON(lrbp->cmd) in ufshcd_queuecommand() cannot trigger on 5.10, and the lrbp->cmd = NULL; added by this patch would be dead code there.

64180742605f is not present in 5.10.y, therefore CVE-2021-47188 does not apply to 5.10.y.

Sorry for the noise.

Thanks,
Vasiliy

Dropped from the 5.10 queue, thanks for the heads-up and the detailed analysis.

--
Thanks,
Sasha