From: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
Date: Tue, 18 Apr 2023 07:04:30 -0700
Subject: [PATCH] drm/i915/dp: prevent potential div-by-zero
References: bsc#1012628
Patch-mainline: 6.3.4
Git-commit: 0ff80028e2702c7c3d78b69705dc47c1ccba8c39
[ Upstream commit 0ff80028e2702c7c3d78b69705dc47c1ccba8c39 ]
drm_dp_dsc_sink_max_slice_count() may return 0 if something goes
wrong on the part of the DSC sink and its DPCD register. This null
value may be later used as a divisor in intel_dsc_compute_params(),
which will lead to an error.
In the unlikely event that this issue occurs, fix it by testing the
return value of drm_dp_dsc_sink_max_slice_count() against zero.
Found by Linux Verification Center (linuxtesting.org) with static
analysis tool SVACE.
Fixes: a4a157777c80 ("drm/i915/dp: Compute DSC pipe config in atomic check")
Signed-off-by: Nikita Zhandarovich <n.zhandarovich@fintech.ru>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230418140430.69902-1-n.zhandarovich@fintech.ru
(cherry picked from commit 51f7008239de011370c5067bbba07f0207f06b72)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/gpu/drm/i915/display/intel_dp.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 62cbab74..c1825f8f 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -1533,6 +1533,11 @@ int intel_dp_dsc_compute_config(struct intel_dp *intel_dp,
pipe_config->dsc.slice_count =
drm_dp_dsc_sink_max_slice_count(intel_dp->dsc_dpcd,
true);
+ if (!pipe_config->dsc.slice_count) {
+ drm_dbg_kms(&dev_priv->drm, "Unsupported Slice Count %d\n",
+ pipe_config->dsc.slice_count);
+ return -EINVAL;
+ }
} else {
u16 dsc_max_output_bpp = 0;
u8 dsc_dp_slice_count;
--
2.35.3