Hey Dan,

On 10/1/2021 6:50 AM, Dan Carpenter wrote:

On Fri, Oct 01, 2021 at 04:49:12PM +0300, Dan Carpenter wrote:

...

Hello Jeykumar Sankaran,

This is a semi-automatic email about new static checker warnings.

The patch 25fdd5933e4c: "drm/msm: Add SDM845 DPU support" from Jun 27, 2018, leads to the following Smatch complaint:

 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c:422 _dpu_hw_sspp_setup_scaler3()
 warn: variable dereferenced before check 'ctx->cap->sblk' (see line 421)

drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c 420 (void)pe; ^^^^^^^^^

Got it. I'll take care of the null pointer issues, but planning to address the `(void)pe` issue in this patch: https://patchwork.freedesktop.org/patch/456592/

Thanks,

Jessica Zhang

...

You should file a bug report with your compiler devs instead of adding these sorts of statements to your code. This function is used as a function pointer so unused parameters are normal.

421		if (_sspp_subblk_offset(ctx, DPU_SSPP_SCALER_QSEED3, &idx) || !sspp
                 ^^^^^^^^^^^^^^^^^^^^

The _sspp_subblk_offset() dereferenced "ctx" before it is checked and then it also derefereces "ctx->cap->sblk" without checking.

422			|| !scaler3_cfg || !ctx || !ctx->cap || !ctx->cap->sblk)
                                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

So these will have already crashed before we reach this point.

Same thing later as well.

drivers/gpu/drm/msm/disp/dpu1/dpu_hw_sspp.c:591 dpu_hw_sspp_setup_creq_lut() warn: variable dereferenced before check 'ctx->cap' (see line 588)

regards, dan carpenter