linux-kernel - [PATCH 09/15] dmaengine: img-mdc: Handle early status read

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Sun, 22 Jul 2018 23:20:04 +0200
From:   Andreas Färber <afaerber@...e.de>
To:     linux-mips@...ux-mips.org
Cc:     Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paul.burton@...s.com>,
        James Hogan <jhogan@...nel.org>, linux-kernel@...r.kernel.org,
        Damien Horsley <damien.horsley@...tec.com>,
        Andreas Färber <afaerber@...e.de>,
        Vinod Koul <vkoul@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        dmaengine@...r.kernel.org
Subject: [PATCH 09/15] dmaengine: img-mdc: Handle early status read

From: Damien Horsley <damien.horsley@...tec.com>

It is possible that mdc_tx_status may be called before the first
node has been read from memory.

In this case, the residue value stored in the register is undefined.
Return the transfer size instead.

Signed-off-by: Damien Horsley <damien.horsley@...tec.com>
Signed-off-by: Andreas Färber <afaerber@...e.de>
---
 drivers/dma/img-mdc-dma.c | 40 ++++++++++++++++++++++++----------------
 1 file changed, 24 insertions(+), 16 deletions(-)

diff --git a/drivers/dma/img-mdc-dma.c b/drivers/dma/img-mdc-dma.c
index 25cec9c243e1..0f2f0f52d83a 100644
--- a/drivers/dma/img-mdc-dma.c
+++ b/drivers/dma/img-mdc-dma.c
@@ -621,25 +621,33 @@ static enum dma_status mdc_tx_status(struct dma_chan *chan,
 			(MDC_CMDS_PROCESSED_CMDS_DONE_MASK + 1);
 
 		/*
-		 * If the command loaded event hasn't been processed yet, then
-		 * the difference above includes an extra command.
+		 * If the first node has not yet been read from memory,
+		 * the residue register value is undefined
 		 */
-		if (!mdesc->cmd_loaded)
-			cmds--;
-		else
-			cmds += mdesc->list_cmds_done;
-
-		bytes = mdesc->list_xfer_size;
-		ldesc = mdesc->list;
-		for (i = 0; i < cmds; i++) {
-			bytes -= ldesc->xfer_size + 1;
-			ldesc = ldesc->next_desc;
-		}
-		if (ldesc) {
-			if (residue != MDC_TRANSFER_SIZE_MASK)
-				bytes -= ldesc->xfer_size - residue;
+		if (!mdesc->cmd_loaded && !cmds) {
+			bytes = mdesc->list_xfer_size;
+		} else {
+			/*
+			 * If the command loaded event hasn't been processed yet, then
+			 * the difference above includes an extra command.
+			 */
+			if (!mdesc->cmd_loaded)
+				cmds--;
 			else
+				cmds += mdesc->list_cmds_done;
+
+			bytes = mdesc->list_xfer_size;
+			ldesc = mdesc->list;
+			for (i = 0; i < cmds; i++) {
 				bytes -= ldesc->xfer_size + 1;
+				ldesc = ldesc->next_desc;
+			}
+			if (ldesc) {
+				if (residue != MDC_TRANSFER_SIZE_MASK)
+					bytes -= ldesc->xfer_size - residue;
+				else
+					bytes -= ldesc->xfer_size + 1;
+			}
 		}
 	}
 	spin_unlock_irqrestore(&mchan->vc.lock, flags);
-- 
2.16.4