Commit f66d8948 authored Sep 26, 2018 by Tomi Valkeinen Committed by Greg Kroah-Hartman Oct 13, 2018

fbdev/omapfb: fix omapfb_memory_read infoleak



commit 1bafcbf59fed92af58955024452f45430d3898c5 upstream.

OMAPFB_MEMORY_READ ioctl reads pixels from the LCD's memory and copies
them to a userspace buffer. The code has two issues:

- The user provided width and height could be large enough to overflow
  the calculations
- The copy_to_user() can copy uninitialized memory to the userspace,
  which might contain sensitive kernel information.

Fix these by limiting the width & height parameters, and only copying
the amount of data that we actually received from the LCD.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reported-by: Jann Horn <jannh@google.com>
Cc: stable@vger.kernel.org
Cc: security@kernel.org
Cc: Will Deacon <will.deacon@arm.com>
Cc: Jann Horn <jannh@google.com>
Cc: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 88736169

drivers/video/fbdev/omap2/omapfb/omapfb-ioctl.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -496,6 +496,9 @@ static int omapfb_memory_read(struct fb_info *fbi,
		if (!access_ok(VERIFY_WRITE, mr->buffer, mr->buffer_size))
		return -EFAULT;

		if (mr->w > 4096 \|\| mr->h > 4096)
		return -EINVAL;

		if (mr->w * mr->h * 3 > mr->buffer_size)
		return -EINVAL;

		@@ -509,7 +512,7 @@ static int omapfb_memory_read(struct fb_info *fbi,
		mr->x, mr->y, mr->w, mr->h);

		if (r > 0) {
		if (copy_to_user(mr->buffer, buf, mr->buffer_size))
		if (copy_to_user(mr->buffer, buf, r))
		r = -EFAULT;
		}