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[73.71.40.85]) by smtp.gmail.com with ESMTPSA id v9sm12447460pgs.3.2019.02.11.11.50.27 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 11 Feb 2019 11:50:28 -0800 (PST) Received: by garbanzo.do-not-panic.com (sSMTP sendmail emulation); Mon, 11 Feb 2019 11:50:25 -0800 Date: Mon, 11 Feb 2019 11:50:25 -0800 From: Luis Chamberlain To: Christian Brauner Cc: akpm@linux-foundation.org, keescook@chromium.org, linux-kernel@vger.kernel.org, ebiederm@xmission.com, joe.lawrence@redhat.com, longman@redhat.com, linux@dominikbrodowski.net, viro@zeniv.linux.org.uk, adobriyan@gmail.com, linux-api@vger.kernel.org Subject: Re: [RFC PATCH v4 3/3] sysctl: return -EINVAL if val violates minmax Message-ID: <20190211195025.GT11489@garbanzo.do-not-panic.com> References: <20190210203943.8227-1-christian@brauner.io> <20190210203943.8227-4-christian@brauner.io> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190210203943.8227-4-christian@brauner.io> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Feb 10, 2019 at 09:39:43PM +0100, Christian Brauner wrote: > Currently when userspace gives us a values that overflow e.g. file-max and > other callers of __do_proc_doulongvec_minmax() we simply > ignore the new value and leave the current value untouched. This can be > problematic as it gives the illusion that the limit has indeed be bumped > when in fact it failed. > This commit makes sure to return EINVAL when an overflow is detected. > Please note that this is a userspace facing change. > Acked-by: Luis Chamberlain Luis > Signed-off-by: Christian Brauner > --- > /* Changelog */ > v4: > - patch introduced > > v1-v3: > - patch not present > --- > kernel/sysctl.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/kernel/sysctl.c b/kernel/sysctl.c > index c4a44b7ccb8a..516bc8a2812d 100644 > --- a/kernel/sysctl.c > +++ b/kernel/sysctl.c > @@ -2846,8 +2846,10 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int > if (neg) > continue; > val = convmul * val / convdiv; > - if ((min && val < *min) || (max && val > *max)) > - continue; > + if ((min && val < *min) || (max && val > *max)) { > + err = -EINVAL; > + break; > + } > *i = val; > } else { > val = convdiv * (*i) / convmul; > -- > 2.20.1 >