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Thu, 10 Apr 2025 15:15:32 -0700 (PDT) Received: from qasdev.system ([2a02:c7c:6696:8300:a7c3:c7a5:ff1b:f4fa]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39eaf445270sm151066f8f.81.2025.04.10.15.15.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Apr 2025 15:15:31 -0700 (PDT) Date: Thu, 10 Apr 2025 23:15:23 +0100 From: Qasim Ijaz To: Jakub Kicinski Cc: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, linux-usb@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, syzbot Subject: Re: [PATCH 1/4] net: fix uninitialised access in mii_nway_restart() Message-ID: References: <20250319112156.48312-1-qasdev00@gmail.com> <20250319112156.48312-2-qasdev00@gmail.com> <20250325063307.15336182@kernel.org> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250325063307.15336182@kernel.org> On Tue, Mar 25, 2025 at 06:33:07AM -0700, Jakub Kicinski wrote: > On Wed, 19 Mar 2025 11:21:53 +0000 Qasim Ijaz wrote: > > --- a/drivers/net/mii.c > > +++ b/drivers/net/mii.c > > @@ -464,6 +464,8 @@ int mii_nway_restart (struct mii_if_info *mii) > > > > /* if autoneg is off, it's an error */ > > bmcr = mii->mdio_read(mii->dev, mii->phy_id, MII_BMCR); > > + if (bmcr < 0) > > + return bmcr; > > > > if (bmcr & BMCR_ANENABLE) { > > bmcr |= BMCR_ANRESTART; > > We error check just one mdio_read() but there's a whole bunch of them > in this file. What's the expected behavior then? Are all of them buggy? > Hi Jakub Apologies for my delayed response, I had another look at this and I think my patch may be off a bit. You are correct that there are multiple mdio_read() calls and looking at the mii.c file we can see that calls to functions like mdio_read (and a lot of others) dont check return values. So in light of this I think a better patch would be to not edit the mii.c file at all and just make ch9200_mdio_read return 0 on error. This way if mdio_read fails and 0 is returned, the check for "bmcr & BMCR_ANENABLE" won't be triggered and mii_nway_restart will just return 0 and end. If we return a negative on error it may contain the exact bit the function checks. Similiar to this patch: If this sounds good, should i send another patch series with all the changes? > This patch should be split into core and driver parts. > -- > pw-bot: cr