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Donenfeld" , , , , Subject: [PATCH] drm/i915/dp: prevent potential div-by-zero Date: Tue, 18 Apr 2023 07:04:30 -0700 Message-ID: <20230418140430.69902-1-n.zhandarovich@fintech.ru> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.0.253.138] X-ClientProxiedBy: Ex16-02.fintech.ru (10.0.10.19) To Ex16-01.fintech.ru (10.0.10.18) X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,SPF_HELO_NONE, SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1763523624026636897?= X-GMAIL-MSGID: =?utf-8?q?1763523624026636897?= 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 --- 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 62cbab7402e9..c1825f8f885c 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;