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[125.30.56.181]) by smtp.gmail.com with ESMTPSA id h11sm16533490pfn.125.2020.04.16.04.32.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 16 Apr 2020 04:32:51 -0700 (PDT) From: Sergey Senozhatsky X-Google-Original-From: Sergey Senozhatsky Date: Thu, 16 Apr 2020 20:32:49 +0900 To: Hans Verkuil Cc: Sergey Senozhatsky , Mauro Carvalho Chehab , Tomasz Figa , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC][PATCH] media: v4l2-ctrls: add more NULL pointer checks Message-ID: <20200416113249.GG30641@jagdpanzerIV.localdomain> References: <20200410103501.1083-1-sergey.senozhatsky@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (20/04/16 10:53), Hans Verkuil wrote: [..] > > +++ b/drivers/media/v4l2-core/v4l2-ctrls.c > > @@ -2869,6 +2869,9 @@ EXPORT_SYMBOL(v4l2_ctrl_add_handler); > > > > bool v4l2_ctrl_radio_filter(const struct v4l2_ctrl *ctrl) > > { > > + if (WARN_ON(!ctrl)) > > + return false; > > + > > if (V4L2_CTRL_ID2WHICH(ctrl->id) == V4L2_CTRL_CLASS_FM_TX) > > return true; > > if (V4L2_CTRL_ID2WHICH(ctrl->id) == V4L2_CTRL_CLASS_FM_RX) > > @@ -3794,7 +3797,9 @@ s32 v4l2_ctrl_g_ctrl(struct v4l2_ctrl *ctrl) > > struct v4l2_ext_control c; > > > > /* It's a driver bug if this happens. */ > > - WARN_ON(!ctrl->is_int); > > + if (WARN_ON(!ctrl || !ctrl->is_int)) > > + return -EINVAL; > > Just return 0 here. The return value is the control's value, not an error code. > So all you can do here is return 0 in the absence of anything better. OK. > > + > > c.value = 0; > > get_ctrl(ctrl, &c); > > return c.value; > > @@ -4212,6 +4217,9 @@ EXPORT_SYMBOL(v4l2_s_ctrl); > > > > int __v4l2_ctrl_s_ctrl(struct v4l2_ctrl *ctrl, s32 val) > > { > > + if (!ctrl) > > Change this to 'if (WARN_ON(!ctrl))' > > I don't think NULL pointers should be silently ignored: it really > indicates a driver bug. It it certainly a good idea to WARN instead. Should WARN_ON() be only in unlocked versions of ctrl API? It probably would make sense to add WARNs to both - e.g. to v4l2_ctrl_s_ctrl() and to __v4l2_ctrl_s_ctrl(). By the way, why don't locked and unlocked versions live together in v4l2-ctrls.c file? Any reason for, e.g., v4l2_ctrl_s_ctrl() to be in header and __v4l2_ctrl_s_ctrl() to be C-file? > The same is true for the functions below. OK. -ss