From: Kees Cook <keescook@chromium.org>
To: "Ruhl, Michael J" <michael.j.ruhl@intel.com>
Cc: "intel-wired-lan@lists.osuosl.org"
<intel-wired-lan@lists.osuosl.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Eric Dumazet <edumazet@google.com>,
"linux-hardening@vger.kernel.org"
<linux-hardening@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
"David S. Miller" <davem@davemloft.net>
Subject: Re: [Intel-wired-lan] [PATCH v3 2/2] igb: Proactively round up to kmalloc bucket size
Date: Tue, 1 Nov 2022 14:37:17 -0700 [thread overview]
Message-ID: <202211011433.A64BF17F46@keescook> (raw)
In-Reply-To: <DM5PR11MB1324802F3F2098CB3239CF36C1379@DM5PR11MB1324.namprd11.prod.outlook.com>
On Mon, Oct 31, 2022 at 08:42:36PM +0000, Ruhl, Michael J wrote:
> Looking at the size usage (from elixir), I see:
>
> --
> if (!q_vector) {
> q_vector = kzalloc(size, GFP_KERNEL);
> } else if (size > ksize(q_vector)) {
> kfree_rcu(q_vector, rcu);
> q_vector = kzalloc(size, GFP_KERNEL);
> } else {
> memset(q_vector, 0, size);
> }
> --
>
> If the size is rounded up, will the (size > ksize()) check ever be true?
>
> I.e. have you eliminated this check (and maybe getting rid of the need for first patch?)?
Hi!
It looked like igb_alloc_q_vector() was designed to be called multiple
times on the same q_vector (i.e. to grow its allocation size over time).
So for that case, yes, the "size > ksize(q_vector)" check is needed. If
it's only ever called once (which is hard for me to tell), then no. (And
if "no", why was the alloc/free case even there in the first place?)
-Kees
--
Kees Cook
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WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: "Ruhl, Michael J" <michael.j.ruhl@intel.com>
Cc: "Brandeburg, Jesse" <jesse.brandeburg@intel.com>,
"Nguyen, Anthony L" <anthony.l.nguyen@intel.com>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
"intel-wired-lan@lists.osuosl.org"
<intel-wired-lan@lists.osuosl.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-hardening@vger.kernel.org"
<linux-hardening@vger.kernel.org>
Subject: Re: [PATCH v3 2/2] igb: Proactively round up to kmalloc bucket size
Date: Tue, 1 Nov 2022 14:37:17 -0700 [thread overview]
Message-ID: <202211011433.A64BF17F46@keescook> (raw)
In-Reply-To: <DM5PR11MB1324802F3F2098CB3239CF36C1379@DM5PR11MB1324.namprd11.prod.outlook.com>
On Mon, Oct 31, 2022 at 08:42:36PM +0000, Ruhl, Michael J wrote:
> Looking at the size usage (from elixir), I see:
>
> --
> if (!q_vector) {
> q_vector = kzalloc(size, GFP_KERNEL);
> } else if (size > ksize(q_vector)) {
> kfree_rcu(q_vector, rcu);
> q_vector = kzalloc(size, GFP_KERNEL);
> } else {
> memset(q_vector, 0, size);
> }
> --
>
> If the size is rounded up, will the (size > ksize()) check ever be true?
>
> I.e. have you eliminated this check (and maybe getting rid of the need for first patch?)?
Hi!
It looked like igb_alloc_q_vector() was designed to be called multiple
times on the same q_vector (i.e. to grow its allocation size over time).
So for that case, yes, the "size > ksize(q_vector)" check is needed. If
it's only ever called once (which is hard for me to tell), then no. (And
if "no", why was the alloc/free case even there in the first place?)
-Kees
--
Kees Cook
next prev parent reply other threads:[~2022-11-01 21:37 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-18 9:25 [Intel-wired-lan] [PATCH v3 0/2] igb: Proactively round up to kmalloc bucket size Kees Cook
2022-10-18 9:25 ` Kees Cook
2022-10-18 9:25 ` [Intel-wired-lan] [PATCH v3 1/2] igb: Do not free q_vector unless new one was allocated Kees Cook
2022-10-18 9:25 ` Kees Cook
2022-10-18 12:20 ` [Intel-wired-lan] " Ruhl, Michael J
2022-10-18 12:20 ` Ruhl, Michael J
2022-10-20 21:59 ` [Intel-wired-lan] " Jacob Keller
2022-10-29 3:29 ` G, GurucharanX
2022-10-29 3:29 ` G, GurucharanX
2022-10-18 9:25 ` [Intel-wired-lan] [PATCH v3 2/2] igb: Proactively round up to kmalloc bucket size Kees Cook
2022-10-18 9:25 ` Kees Cook
2022-10-29 3:17 ` [Intel-wired-lan] " Kees Cook
2022-10-29 3:17 ` Kees Cook
2022-10-31 20:42 ` [Intel-wired-lan] " Ruhl, Michael J
2022-10-31 20:42 ` Ruhl, Michael J
2022-11-01 21:37 ` Kees Cook [this message]
2022-11-01 21:37 ` Kees Cook
2022-11-02 14:12 ` [Intel-wired-lan] " Ruhl, Michael J
2022-11-02 14:12 ` Ruhl, Michael J
2022-10-29 3:30 ` [Intel-wired-lan] " G, GurucharanX
2022-10-29 3:30 ` G, GurucharanX
2022-10-18 10:09 ` [Intel-wired-lan] [PATCH v3 0/2] " Kees Cook
2022-10-18 10:09 ` Kees Cook
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