From: Michal Hocko <mhocko@kernel.org>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Jens Axboe <axboe@kernel.dk>,
Amritha Nambiar <amritha.nambiar@intel.com>,
Willem de Bruijn <willemb@google.com>,
kernel-janitors@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 1/2] cpumask: Introduce possible_cpu_safe()
Date: Thu, 4 Apr 2019 12:35:28 +0200 [thread overview]
Message-ID: <20190404103528.GG12864@dhcp22.suse.cz> (raw)
In-Reply-To: <20190404100218.GA26946@kadam>
On Thu 04-04-19 13:02:19, Dan Carpenter wrote:
> There have been two cases recently where we pass user a controlled "cpu"
> to possible_cpus(). That's not allowed. If it's invalid, it will
> trigger a WARN_ONCE() and an out of bounds read which could result in an
> Oops.
>
> This patch introduces possible_cpu_safe() which first checks to see if
> the cpu is valid, turns off speculation and then checks if the cpu is
> possible.
Why cannot we do the check in possible_cpu directly? Is it used from any
hot path? I am quite skeptical people will use the new helper
consistently.
--
Michal Hocko
SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org>
To: Dan Carpenter <dan.carpenter@oracle.com>
Cc: "David S. Miller" <davem@davemloft.net>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Jens Axboe <axboe@kernel.dk>,
Amritha Nambiar <amritha.nambiar@intel.com>,
Willem de Bruijn <willemb@google.com>,
kernel-janitors@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 1/2] cpumask: Introduce possible_cpu_safe()
Date: Thu, 04 Apr 2019 10:35:28 +0000 [thread overview]
Message-ID: <20190404103528.GG12864@dhcp22.suse.cz> (raw)
In-Reply-To: <20190404100218.GA26946@kadam>
On Thu 04-04-19 13:02:19, Dan Carpenter wrote:
> There have been two cases recently where we pass user a controlled "cpu"
> to possible_cpus(). That's not allowed. If it's invalid, it will
> trigger a WARN_ONCE() and an out of bounds read which could result in an
> Oops.
>
> This patch introduces possible_cpu_safe() which first checks to see if
> the cpu is valid, turns off speculation and then checks if the cpu is
> possible.
Why cannot we do the check in possible_cpu directly? Is it used from any
hot path? I am quite skeptical people will use the new helper
consistently.
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-04-04 10:35 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-04 10:02 [PATCH 1/2] cpumask: Introduce possible_cpu_safe() Dan Carpenter
2019-04-04 10:02 ` Dan Carpenter
2019-04-04 10:04 ` [PATCH 2/2] io_uring: Potential Oops in io_sq_offload_start() Dan Carpenter
2019-04-04 10:04 ` Dan Carpenter
2019-04-04 10:35 ` Michal Hocko [this message]
2019-04-04 10:35 ` [PATCH 1/2] cpumask: Introduce possible_cpu_safe() Michal Hocko
2019-04-04 11:28 ` Peter Zijlstra
2019-04-04 11:28 ` Peter Zijlstra
2019-04-04 10:45 ` Peter Zijlstra
2019-04-04 10:45 ` Peter Zijlstra
2019-04-08 8:09 ` [PATCH v2 " Dan Carpenter
2019-04-08 8:09 ` Dan Carpenter
2019-04-08 8:15 ` [PATCH v2 2/2] io_uring: Potential Oops in io_sq_offload_start() Dan Carpenter
2019-04-08 8:15 ` Dan Carpenter
2019-04-30 9:26 ` Dan Carpenter
2019-04-30 9:26 ` Dan Carpenter
2019-05-03 11:43 ` Dan Carpenter
2019-05-03 11:43 ` Dan Carpenter
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