Bug 96306

Summary:

BUG: KASAN: slab-out-of-bounds in OUT_RINGp (via nvc0_fbcon_imageblit)

Product:

xorg

Reporter:

Peter Wu <peter>

Component:

Driver/nouveau

Assignee:

Nouveau Project <nouveau>

Status:

RESOLVED FIXED

QA Contact:

Xorg Project Team <xorg-team>

Severity:

normal

Priority:

medium

CC:

peter

Version:

unspecified

Hardware:

x86-64 (AMD64)

OS:

Linux (All)

Whiteboard:

i915 platform:

i915 features:

Attachments:

Description	Flags
dmesg output for v4.7-rc1 containing the KASAN report	none

Description Peter Wu 2016-06-01 11:44:07 UTC

Created attachment 124231 [details]
dmesg output for v4.7-rc1 containing the KASAN report

Previously reported by others to mailing lists (with no replies):

[4.4-rc1] nouveau: BUG: KASAN: slab-out-of-bounds in memcpy+0x1d/0x40
https://lists.freedesktop.org/archives/dri-devel/2015-November/095100.html

[3.10] BUG: drm, nouveau: slab-out-of-bounds read access in nv50_fbcon_imageblit()
https://lists.freedesktop.org/archives/dri-devel/2016-May/108270.html


Hardware:
Optimus laptop with inteldrmfb being the primary framebuffer, an external monitor is connected to DP-1 on the Nvidia card (GTX 965M, 10de:13d9).

Steps to reproduce the out-of-bounds issue in my environment:
 0. Avoid continuously triggering the error: dmesg -D
 1. modprobe nouveau runpm=0 (or be sure to wake the device before using con2fbmap, there is a nasty (unrelated) deadlock in there due to recursive console_lockup.)
 2. con2fbmap 1 2 (bind console 2 to nouveaufb (1)). This invokes ioctl(/dev/fb0, FBIOPUT_CON2FBMAP, (u32[2]){2, 1})).
 3. If you are not there already, switch to tty2 on the nouveau display.
 4. Press Enter until you are at the last line of the console (or past it, I forgot).
 5. Go to a different tty (e.g. the Intel one) and notice the KASAN report in dmesg.

Attached is yet another log (looks similar to the other ones) for v4.7-rc1 (with two unrelated patchsets applied on top).

Comment 1 Peter Wu 2016-07-07 21:59:55 UTC

Fixed since v4.7-rc3 with:

commit f045f459d925138fe7d6193a8c86406bda7e49da
Author: Ben Skeggs <bskeggs@redhat.com>
Date:   Thu Jun 2 12:23:31 2016 +1000

    drm/nouveau/fbcon: fix out-of-bounds memory accesses
    
    Reported by KASAN.
    
    Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
    Cc: stable@vger.kernel.org

Confirmed that is does no longer occur in v4.7-rc6-74-g076501f.

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