linux-kernel - drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.c:31 dpu_setup_dspp_pcc() warn: variable dereferenced before check 'ctx' (see line 29)

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Date:   Mon, 1 Mar 2021 09:58:36 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     kbuild@...ts.01.org, Kalyan Thota <kalyan_t@...eaurora.org>
Cc:     lkp@...el.com, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org, Rob Clark <robdclark@...omium.org>
Subject: drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.c:31 dpu_setup_dspp_pcc()
 warn: variable dereferenced before check 'ctx' (see line 29)

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   fe07bfda2fb9cdef8a4d4008a409bb02f35f1bd8
commit: 4259ff7ae509ed880b3a7bb685972c3a3bf4b74b drm/msm/dpu: add support for pcc color block in dpu driver
config: arm64-randconfig-m031-20210301 (attached as .config)
compiler: aarch64-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>

smatch warnings:
drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.c:31 dpu_setup_dspp_pcc() warn: variable dereferenced before check 'ctx' (see line 29)

vim +/ctx +31 drivers/gpu/drm/msm/disp/dpu1/dpu_hw_dspp.c

4259ff7ae509ed Kalyan Thota 2020-03-24  28  
4259ff7ae509ed Kalyan Thota 2020-03-24 @29  	u32 base = ctx->cap->sblk->pcc.base;
                                                           ^^^^^
Dereference

4259ff7ae509ed Kalyan Thota 2020-03-24  30  
4259ff7ae509ed Kalyan Thota 2020-03-24 @31  	if (!ctx || !base) {
                                                    ^^^^
Checked too late

4259ff7ae509ed Kalyan Thota 2020-03-24  32  		DRM_ERROR("invalid ctx %pK pcc base 0x%x\n", ctx, base);
4259ff7ae509ed Kalyan Thota 2020-03-24  33  		return;
4259ff7ae509ed Kalyan Thota 2020-03-24  34  	}

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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