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[80.7.220.175]) by smtp.gmail.com with ESMTPSA id q24sm2040048wmq.24.2021.02.02.01.25.43 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 02 Feb 2021 01:25:43 -0800 (PST) Date: Tue, 2 Feb 2021 09:25:41 +0000 From: Daniel Thompson To: Wenjia Zhao Cc: Lee Jones , Jingoo Han , Bartlomiej Zolnierkiewicz , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] backlight: pcf50633: pdata may be a null pointer, null pointer dereference cause crash Message-ID: <20210202092541.2wvzpe53mavrd47x@maple.lan> References: <1612190499-73818-1-git-send-email-driverfuzzing@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1612190499-73818-1-git-send-email-driverfuzzing@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org On Mon, Feb 01, 2021 at 08:41:38AM -0600, Wenjia Zhao wrote: > Signed-off-by: Wenjia Zhao There should be a patch description here explaining why the patch is needed and how it works. > --- > drivers/video/backlight/pcf50633-backlight.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/video/backlight/pcf50633-backlight.c b/drivers/video/backlight/pcf50633-backlight.c > index 540dd338..43267af 100644 > --- a/drivers/video/backlight/pcf50633-backlight.c > +++ b/drivers/video/backlight/pcf50633-backlight.c > @@ -127,7 +127,8 @@ static int pcf50633_bl_probe(struct platform_device *pdev) > > platform_set_drvdata(pdev, pcf_bl); > > - pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time); > + if (pdata) > + pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time); Assuming you found this issue using a static analyzer then I think it might be better to if an "if (!pdata) return -EINVAL" further up the file instead. In other words it is better to "document" (via the return code) that the code does not support pdata == NULL than to add another untested code path. Daniel.