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Sun, 23 Nov 2025 23:56:42 -0800 (PST) Date: Mon, 24 Nov 2025 10:56:38 +0300 From: Dan Carpenter To: Conor Dooley Cc: Mark Brown , Prajna Rajendra Kumar , Conor Dooley , linux-spi@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: Re: [PATCH next] spi: Fix potential uninitialized variable in probe() Message-ID: References: <20251121-apostle-stark-7af8aebfe9c1@spud> Precedence: bulk X-Mailing-List: linux-kernel@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: <20251121-apostle-stark-7af8aebfe9c1@spud> On Fri, Nov 21, 2025 at 04:20:41PM +0000, Conor Dooley wrote: > On Fri, Nov 21, 2025 at 02:18:49PM +0000, Mark Brown wrote: > > On Fri, Nov 21, 2025 at 04:35:01PM +0300, Dan Carpenter wrote: > > > If the device tree is messed up, then potentially the "protocol" string > > > could potentially be uninitialized. Add a check to prevent that. > > > > > > Fixes: 059f545832be ("spi: add support for microchip "soft" spi controller") > > > Signed-off-by: Dan Carpenter > > > --- > > > drivers/spi/spi-microchip-core-spi.c | 2 ++ > > > 1 file changed, 2 insertions(+) > > > > > > diff --git a/drivers/spi/spi-microchip-core-spi.c b/drivers/spi/spi-microchip-core-spi.c > > > index b8738190cdcb..e65036cc62f3 100644 > > > --- a/drivers/spi/spi-microchip-core-spi.c > > > +++ b/drivers/spi/spi-microchip-core-spi.c > > > @@ -320,6 +320,8 @@ static int mchp_corespi_probe(struct platform_device *pdev) > > > */ > > > ret = of_property_read_string(pdev->dev.of_node, "microchip,protocol-configuration", > > > &protocol); > > > + if (ret) > > > + return ret; > > > if (strcmp(protocol, "motorola") != 0) > > > return dev_err_probe(&pdev->dev, -EINVAL, > > > "CoreSPI: protocol '%s' not supported by this driver\n", > > > > This should probably also complain about not being able to get the > > property, otherwise nobody is going to be able to figure out what's > > wrong if we actually hit the error case. > > The one thing to be careful of is that the property has a default, so > EINVAL needs to be treated differently, so the decision tree is > something like: > if (ret == _EINVAL) > > else if (ret) > abort complaining about malformed > else if (!motorola) > abort complaining about unsupported mode > else > > > obviously that can just become two clauses, but you get the idea. Sure. I've sent a v2 which defaults to motorola. regards, dan carpenter