linux-kernel - [PATCH] drivers/tty: Use get_user instead of dereferencing user pointer

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, 20 Apr 2012 17:52:34 +0200
From:	Emil Goode <emilgoode@...il.com>
To:	gregkh@...uxfoundation.org
Cc:	kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org,
	Emil Goode <emilgoode@...il.com>
Subject: [PATCH] drivers/tty: Use get_user instead of dereferencing user pointer

We should use the get_user macro instead of dereferencing user
pointers directly.

This patch fixes the following sparse warning:
drivers/tty/n_tty.c:1648:51: warning:
	dereference of noderef expression

Signed-off-by: Emil Goode <emilgoode@...il.com>
---
I'm a newbie so please review carefully.
Not sure if I should add error handling for the get_user call here.

 drivers/tty/n_tty.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index 94b6eda..5ff63cc 100644
--- a/drivers/tty/n_tty.c
+++ b/drivers/tty/n_tty.c
@@ -1630,6 +1630,7 @@ static int copy_from_read_buf(struct tty_struct *tty,
 	int retval;
 	size_t n;
 	unsigned long flags;
+	unsigned char ch;
 
 	retval = 0;
 	spin_lock_irqsave(&tty->read_lock, flags);
@@ -1645,7 +1646,8 @@ static int copy_from_read_buf(struct tty_struct *tty,
 		tty->read_cnt -= n;
 		/* Turn single EOF into zero-length read */
 		if (L_EXTPROC(tty) && tty->icanon && n == 1) {
-			if (!tty->read_cnt && (*b)[n-1] == EOF_CHAR(tty))
+			get_user(ch, b[n-1]);
+			if (!tty->read_cnt && ch == EOF_CHAR(tty))
 				n--;
 		}
 		spin_unlock_irqrestore(&tty->read_lock, flags);
-- 
1.7.9.5

--
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/