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From: Eric Biggers <ebiggers@kernel.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>
Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
	Al Viro <viro@zeniv.linux.org.uk>
Subject: [PATCH v2 1/2] tty: fix compat TIOCGSERIAL leaking uninitialized memory
Date: Mon, 24 Feb 2020 10:20:43 -0800
Message-ID: <20200224182044.234553-2-ebiggers@kernel.org> (raw)
In-Reply-To: <20200224182044.234553-1-ebiggers@kernel.org>

From: Eric Biggers <ebiggers@google.com>

Commit 77654350306a ("take compat TIOC[SG]SERIAL treatment into
tty_compat_ioctl()") changed the compat version of TIOCGSERIAL to start
copying a whole 'serial_struct32' to userspace rather than individual
fields, but failed to initialize all padding and fields -- namely the
hole after the 'iomem_reg_shift' field, and the 'reserved' field.

Fix this by initializing the struct to zero.

[v2: use sizeof, and convert the adjacent line for consistency.]

Reported-by: syzbot+8da9175e28eadcb203ce@syzkaller.appspotmail.com
Fixes: 77654350306a ("take compat TIOC[SG]SERIAL treatment into tty_compat_ioctl()")
Cc: <stable@vger.kernel.org> # v4.20+
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 drivers/tty/tty_io.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/tty_io.c b/drivers/tty/tty_io.c
index 1fcf7ad83dfa0a..db4a13bc855ed6 100644
--- a/drivers/tty/tty_io.c
+++ b/drivers/tty/tty_io.c
@@ -2730,7 +2730,9 @@ static int compat_tty_tiocgserial(struct tty_struct *tty,
 	struct serial_struct32 v32;
 	struct serial_struct v;
 	int err;
-	memset(&v, 0, sizeof(struct serial_struct));
+
+	memset(&v, 0, sizeof(v));
+	memset(&v32, 0, sizeof(v32));
 
 	if (!tty->ops->set_serial)
 		return -ENOTTY;
-- 
2.25.0.265.gbab2e86ba0-goog


  reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-24  8:18 KMSAN: kernel-infoleak in tty_compat_ioctl syzbot
2020-02-24  8:38 ` [PATCH] tty: fix compat TIOCGSERIAL leaking uninitialized memory Eric Biggers
2020-02-24  8:47   ` Jiri Slaby
2020-02-24 18:15     ` Eric Biggers
2020-02-24 18:20       ` [PATCH v2 0/2] tty: fix bugs in compat TIOCGSERIAL Eric Biggers
2020-02-24 18:20         ` Eric Biggers [this message]
2020-02-25  7:30           ` [PATCH v2 1/2] tty: fix compat TIOCGSERIAL leaking uninitialized memory Jiri Slaby
2020-03-02 21:24             ` Eric Biggers
2020-03-03  6:29               ` Greg Kroah-Hartman
2020-03-18 12:00               ` Greg Kroah-Hartman
2020-03-18 16:36                 ` Eric Biggers
2020-02-24 18:20         ` [PATCH v2 2/2] tty: fix compat TIOCGSERIAL checking wrong function ptr Eric Biggers
2020-02-25  7:30           ` Jiri Slaby

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