From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean Delvare Subject: Re: [PATCH] i2c: strncpy does not null terminate string Date: Fri, 17 Jul 2009 15:13:17 +0200 Message-ID: <20090717151317.021e9faa@hyperion.delvare> References: <4A60769C.9010707@gmail.com> <20090717150624.4a0636f7@hyperion.delvare> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090717150624.4a0636f7-ig7AzVSIIG7kN2dkZ6Wm7A@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Roel Kluin Cc: ben-linux-elnMNo+KYs3YtjvyW6yDsg@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andrew Morton List-Id: linux-i2c@vger.kernel.org Oh, BTW... On Fri, 17 Jul 2009 15:06:24 +0200, Jean Delvare wrote: > On Fri, 17 Jul 2009 15:03:24 +0200, Roel Kluin wrote: > > With `sizeof(string) - 1` strncpy() will null terminate the string. > > > > Signed-off-by: Roel Kluin > > --- > > To test this: > > > > #include > > #include > > > > char a[10]; > > char b[10]; > > > > int main() > > { > > const char* str = "0123456789012"; > > strncpy(a, str, sizeof(a)); > > strncpy(b, str, sizeof(b) - 1); > > printf("String a was %s, b was %s\n", a, b); > > > > return 0; > > } You can't compare user-space code and kernel code, as libc implementations can differ. For example, snprintf() in user-space may not NULL-terminate the string while the kernel implementation always does. > > > > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c > > index fdd8327..bede75d 100644 > > --- a/drivers/i2c/busses/i2c-omap.c > > +++ b/drivers/i2c/busses/i2c-omap.c > > @@ -879,7 +879,7 @@ omap_i2c_probe(struct platform_device *pdev) > > i2c_set_adapdata(adap, dev); > > adap->owner = THIS_MODULE; > > adap->class = I2C_CLASS_HWMON; > > - strncpy(adap->name, "OMAP I2C adapter", sizeof(adap->name)); > > + strncpy(adap->name, "OMAP I2C adapter", sizeof(adap->name) - 1); > > adap->algo = &omap_i2c_algo; > > adap->dev.parent = &pdev->dev; > > Nack, please just use strlcpy() instead. > > IMHO strncpy() should be banned from the kernel. > -- Jean Delvare