linux-kernel - [PATCH] drm/etnaviv: fix perfmon domain interation

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]

Message-Id: <20200511123744.96246-1-christian.gmeiner@gmail.com>
Date:   Mon, 11 May 2020 14:37:33 +0200
From:   Christian Gmeiner <christian.gmeiner@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     Christian Gmeiner <christian.gmeiner@...il.com>,
        Paul Cercueil <paul@...pouillou.net>, stable@...r.kernel.or,
        Lucas Stach <l.stach@...gutronix.de>,
        Russell King <linux+etnaviv@...linux.org.uk>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>, etnaviv@...ts.freedesktop.org,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH] drm/etnaviv: fix perfmon domain interation

The GC860 has one GPU device which has a 2d and 3d core. In this case
we want to expose perfmon information for both cores.

The driver has one array which contains all possible perfmon domains
with some meta data - doms_meta. Here we can see that for the GC860
two elements of that array are relevant:

  doms_3d: is at index 0 in the doms_meta array with 8 perfmon domains
  doms_2d: is at index 1 in the doms_meta array with 1 perfmon domain

The userspace driver wants to get a list of all perfmon domains and
their perfmon signals. This is done by iterating over all domains and
their signals. If the userspace driver wants to access the domain with
id 8 the kernel driver fails and returns invalid data from doms_3d with
and invalid offset.

This results in:
  Unable to handle kernel paging request at virtual address 00000000

On such a device it is not possible to use the userspace driver at all.

The fix for this off-by-one error is quite simple.

Reported-by: Paul Cercueil <paul@...pouillou.net>
Tested-by: Paul Cercueil <paul@...pouillou.net>
Fixes: ed1dd899baa3 ("drm/etnaviv: rework perfmon query infrastructure")
Cc: stable@...r.kernel.or
Signed-off-by: Christian Gmeiner <christian.gmeiner@...il.com>
---
 drivers/gpu/drm/etnaviv/etnaviv_perfmon.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c b/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
index e6795bafcbb9..35f7171e779a 100644
--- a/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
+++ b/drivers/gpu/drm/etnaviv/etnaviv_perfmon.c
@@ -453,7 +453,7 @@ static const struct etnaviv_pm_domain *pm_domain(const struct etnaviv_gpu *gpu,
 		if (!(gpu->identity.features & meta->feature))
 			continue;
 
-		if (meta->nr_domains < (index - offset)) {
+		if ((meta->nr_domains - 1) < (index - offset)) {
 			offset += meta->nr_domains;
 			continue;
 		}
-- 
2.26.2