linux-kernel - [PATCHv2] dma: at_hdmac: fix invalid remaining bytes detection

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-next>] [day] [month] [year] [list]

Date:	Fri,  1 Aug 2014 18:51:46 +0200
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Nicolas Ferre <nicolas.ferre@...el.com>,
	Vinod Koul <vinod.koul@...el.com>
Cc:	Dan Williams <dan.j.williams@...el.com>,
	Ludovic Desroches <ludovic.desroches@...el.com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	dmaengine@...r.kernel.org,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Subject: [PATCHv2] dma: at_hdmac: fix invalid remaining bytes detection

Found using smatch:
drivers/dma/at_hdmac.c:299 atc_get_bytes_left() warn: unsigned
'atchan->remain_desc' is never less than zero.

Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
---

Changes in v2:
 - remove unnecessary parentheses

 drivers/dma/at_hdmac.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index c13a3bb0f594..adb0fbc63f16 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -294,14 +294,16 @@ static int atc_get_bytes_left(struct dma_chan *chan)
 			ret = -EINVAL;
 			goto out;
 		}
-		atchan->remain_desc -= (desc_cur->lli.ctrla & ATC_BTSIZE_MAX)
-						<< (desc_first->tx_width);
-		if (atchan->remain_desc < 0) {
+
+		count = (desc_cur->lli.ctrla & ATC_BTSIZE_MAX)
+			<< desc_first->tx_width;
+		if (atchan->remain_desc < count) {
 			ret = -EINVAL;
 			goto out;
-		} else {
-			ret = atchan->remain_desc;
 		}
+
+		atchan->remain_desc -= count;
+		ret = atchan->remain_desc;
 	} else {
 		/*
 		 * Get residual bytes when current
-- 
1.9.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/