linux-kernel - [patch -resend] paride: underflow bug in pg

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Date:	Thu, 17 Oct 2013 19:44:19 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Tim Waugh <tim@...erelk.net>, akpm@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [patch -resend] paride: underflow bug in pg_write()

The test here can underflow so we pass bogus lengths to the hardware.
It's a static checker fix and I don't know the impact.

Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
I sent this originally Jul 31, 2013 but there was no response.

diff --git a/drivers/block/paride/pg.c b/drivers/block/paride/pg.c
index 4a27b1d..2ce3dfd 100644
--- a/drivers/block/paride/pg.c
+++ b/drivers/block/paride/pg.c
@@ -581,7 +581,7 @@ static ssize_t pg_write(struct file *filp, const char __user *buf, size_t count,
 
 	if (hdr.magic != PG_MAGIC)
 		return -EINVAL;
-	if (hdr.dlen > PG_MAX_DATA)
+	if (hdr.dlen < 0 || hdr.dlen > PG_MAX_DATA)
 		return -EINVAL;
 	if ((count - hs) > PG_MAX_DATA)
 		return -EINVAL;
--
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