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[212.51.149.96]) by smtp.gmail.com with ESMTPSA id z26sm1479738wmk.33.2019.11.26.06.40.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 Nov 2019 06:40:32 -0800 (PST) Date: Tue, 26 Nov 2019 15:40:30 +0100 From: Daniel Vetter To: Ville Syrjala Cc: dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, stable@vger.kernel.org, Maarten Lankhorst , Benjamin Gaignard , Daniel Vetter Subject: Re: [PATCH v2 1/4] drm/rect: Avoid division by zero Message-ID: <20191126144030.GY29965@phenom.ffwll.local> References: <20191122175623.13565-1-ville.syrjala@linux.intel.com> <20191122175623.13565-2-ville.syrjala@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20191122175623.13565-2-ville.syrjala@linux.intel.com> X-Operating-System: Linux phenom 5.3.0-2-amd64 User-Agent: Mutt/1.12.2 (2019-09-21) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Fri, Nov 22, 2019 at 07:56:20PM +0200, Ville Syrjala wrote: > From: Ville Syrjälä > > Check for zero width/height destination rectangle in > drm_rect_clip_scaled() to avoid a division by zero. > > Cc: stable@vger.kernel.org > Fixes: f96bdf564f3e ("drm/rect: Handle rounding errors in drm_rect_clip_scaled, v3.") > Cc: Maarten Lankhorst > Cc: Benjamin Gaignard > Cc: Daniel Vetter > Testcase: igt/kms_selftest/drm_rect_clip_scaled_div_by_zero > Signed-off-by: Ville Syrjälä Clamping src to 0 if dst is 0 makes sense to me. Reviewed-by: Daniel Vetter > --- > drivers/gpu/drm/drm_rect.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/drm_rect.c b/drivers/gpu/drm/drm_rect.c > index b8363aaa9032..818738e83d06 100644 > --- a/drivers/gpu/drm/drm_rect.c > +++ b/drivers/gpu/drm/drm_rect.c > @@ -54,7 +54,12 @@ EXPORT_SYMBOL(drm_rect_intersect); > > static u32 clip_scaled(u32 src, u32 dst, u32 clip) > { > - u64 tmp = mul_u32_u32(src, dst - clip); > + u64 tmp; > + > + if (dst == 0) > + return 0; > + > + tmp = mul_u32_u32(src, dst - clip); > > /* > * Round toward 1.0 when clipping so that we don't accidentally > -- > 2.23.0 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch