From: David Laight <David.Laight@ACULAB.COM>
To: 'Greg Kroah-Hartman' <gregkh@linuxfoundation.org>,
Peilin Ye <yepeilin.cs@gmail.com>,
Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "linux-fbdev@vger.kernel.org" <linux-fbdev@vger.kernel.org>,
Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
Jiri Slaby <jirislaby@kernel.org>,
"syzkaller-bugs@googlegroups.com"
<syzkaller-bugs@googlegroups.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
"linux-kernel-mentees@lists.linuxfoundation.org"
<linux-kernel-mentees@lists.linuxfoundation.org>
Subject: RE: [PATCH 0/3] Prevent out-of-bounds access for built-in font data buffers
Date: Thu, 24 Sep 2020 14:42:18 +0000 [thread overview]
Message-ID: <394733ab6fae47488d078cb22f22a85b@AcuMS.aculab.com> (raw)
In-Reply-To: <20200924140937.GA749208@kroah.com>
> On Thu, Sep 24, 2020 at 09:38:22AM -0400, Peilin Ye wrote:
> > Hi all,
> >
> > syzbot has reported [1] a global out-of-bounds read issue in
> > fbcon_get_font(). A malicious user may resize `vc_font.height` to a large
> > value in vt_ioctl(), causing fbcon_get_font() to overflow our built-in
> > font data buffers, declared in lib/fonts/font_*.c:
...
> > (drivers/video/fbdev/core/fbcon.c)
> > if (font->width <= 8) {
> > j = vc->vc_font.height;
> > + if (font->charcount * j > FNTSIZE(fontdata))
> > + return -EINVAL;
Can that still go wrong because the multiply wraps?
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2020-09-24 14:42 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-10 4:35 KASAN: global-out-of-bounds Read in fbcon_get_font syzbot
2020-01-01 17:40 ` syzbot
2020-09-24 13:38 ` [PATCH 0/3] Prevent out-of-bounds access for built-in font data buffers Peilin Ye
2020-09-24 13:40 ` [PATCH 1/3] fbdev, newport_con: Move FONT_EXTRA_WORDS macros into linux/font.h Peilin Ye
2020-09-24 13:42 ` [PATCH 2/3] Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts Peilin Ye
2020-09-24 13:43 ` [PATCH 3/3] fbcon: Fix global-out-of-bounds read in fbcon_get_font() Peilin Ye
2020-09-24 14:09 ` [PATCH 0/3] Prevent out-of-bounds access for built-in font data buffers Greg Kroah-Hartman
2020-09-24 14:25 ` Peilin Ye
2020-09-24 14:42 ` David Laight [this message]
2020-09-24 15:30 ` Peilin Ye
2020-09-24 15:45 ` Dan Carpenter
2020-09-24 16:59 ` Peilin Ye
2020-09-25 8:38 ` Daniel Vetter
2020-09-25 6:46 ` Jiri Slaby
2020-09-25 10:13 ` Peilin Ye
2020-09-25 13:25 ` Daniel Vetter
2020-09-25 15:35 ` Peilin Ye
2020-09-29 9:09 ` Daniel Vetter
2020-09-29 9:44 ` Peilin Ye
2020-09-29 12:34 ` Peilin Ye
2020-09-29 14:38 ` Daniel Vetter
2020-09-30 7:11 ` Peilin Ye
2020-09-30 9:53 ` Daniel Vetter
2020-09-30 10:55 ` Peilin Ye
2020-09-30 11:25 ` Daniel Vetter
2020-09-30 11:52 ` Greg Kroah-Hartman
2020-09-30 12:58 ` Peilin Ye
2020-09-30 5:26 ` Jiri Slaby
2020-09-30 7:16 ` Peilin Ye
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