From: Nikita Zhandarovich Date: Tue, 18 Apr 2023 14:04:30 +0000 (-0700) Subject: drm/i915/dp: prevent potential div-by-zero X-Git-Tag: v6.1.37~1155 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=86d73b1f98a81f3ecfc19dfe6f8d50daf5707330;p=platform%2Fkernel%2Flinux-starfive.git drm/i915/dp: prevent potential div-by-zero [ 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 Reviewed-by: Rodrigo Vivi Signed-off-by: Rodrigo Vivi Link: https://patchwork.freedesktop.org/patch/msgid/20230418140430.69902-1-n.zhandarovich@fintech.ru (cherry picked from commit 51f7008239de011370c5067bbba07f0207f06b72) Signed-off-by: Joonas Lahtinen Signed-off-by: Sasha Levin --- diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c index 2e09899..b165330 100644 --- a/drivers/gpu/drm/i915/display/intel_dp.c +++ b/drivers/gpu/drm/i915/display/intel_dp.c @@ -1512,6 +1512,11 @@ static 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; u8 dsc_dp_slice_count;