patch "staging: mt7621-dma: fix potentially dereferencing uninitialized" added to staging-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    staging: mt7621-dma: fix potentially dereferencing uninitialized

to my staging git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From 354e379684fcc70ab8d5450b4d57bd92b5294dfd Mon Sep 17 00:00:00 2001
From: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Date: Sat, 20 Oct 2018 13:31:06 +0200
Subject: staging: mt7621-dma: fix potentially dereferencing uninitialized
 'tx_desc'

Function 'mtk_hsdma_start_transfer' uses 'tx_desc' pointer which can be
dereferenced before it is initializated. Initializate pointer before
avoiding the problem.

Fixes: 0853c7a53eb3 ("staging: mt7621-dma: ralink: add rt2880 dma engine")
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/staging/mt7621-dma/mtk-hsdma.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/mt7621-dma/mtk-hsdma.c b/drivers/staging/mt7621-dma/mtk-hsdma.c
index df6ebf41bdea..5831f816c17b 100644
--- a/drivers/staging/mt7621-dma/mtk-hsdma.c
+++ b/drivers/staging/mt7621-dma/mtk-hsdma.c
@@ -335,6 +335,8 @@ static int mtk_hsdma_start_transfer(struct mtk_hsdam_engine *hsdma,
 	/* tx desc */
 	src = sg->src_addr;
 	for (i = 0; i < chan->desc->num_sgs; i++) {
+		tx_desc = &chan->tx_ring[chan->tx_idx];
+
 		if (len > HSDMA_MAX_PLEN)
 			tlen = HSDMA_MAX_PLEN;
 		else
@@ -344,7 +346,6 @@ static int mtk_hsdma_start_transfer(struct mtk_hsdam_engine *hsdma,
 			tx_desc->addr1 = src;
 			tx_desc->flags |= HSDMA_DESC_PLEN1(tlen);
 		} else {
-			tx_desc = &chan->tx_ring[chan->tx_idx];
 			tx_desc->addr0 = src;
 			tx_desc->flags = HSDMA_DESC_PLEN0(tlen);
 
-- 
2.19.1