From: Joe Perches <joe@perches.com>
To: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Cc: Linux-ALSA <alsa-devel@alsa-project.org>,
kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
"David Airlie" <airlied@linux.ie>,
"Gustavo Padovan" <gustavo@padovan.org>,
linux-drm <dri-devel@lists.freedesktop.org>,
"Jaroslav Kysela" <perex@perex.cz>,
linux-mm@kvack.org, "Christoph Lameter" <cl@linux.com>,
"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
"Bartosz Golaszewski" <brgl@bgdev.pl>,
"Alexander Shishkin" <alexander.shishkin@linux.intel.com>,
"David Rientjes" <rientjes@google.com>,
virtualization@lists.linux-foundation.org,
"Jason Wang" <jasowang@redhat.com>,
linux-media <linux-media@vger.kernel.org>,
"Robert Richter" <rric@kernel.org>,
"Thomas Zimmermann" <tzimmermann@suse.de>,
linaro-mm-sig@lists.linaro.org,
linux-gpio <linux-gpio@vger.kernel.org>,
"Borislav Petkov" <bp@alien8.de>,
"Mauro Carvalho Chehab" <mchehab@kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
linux-edac@vger.kernel.org, "Tony Luck" <tony.luck@intel.com>,
netdev <netdev@vger.kernel.org>, "Takashi Iwai" <tiwai@suse.com>,
LKML <linux-kernel@vger.kernel.org>,
"Pekka Enberg" <penberg@kernel.org>,
"James Morse" <james.morse@arm.com>,
"Joonsoo Kim" <iamjoonsoo.kim@lge.com>,
"Christian König" <christian.koenig@amd.com>
Subject: Re: [PATCH 3/8] vhost: vringh: use krealloc_array()
Date: Tue, 27 Oct 2020 10:08:02 -0700 [thread overview]
Message-ID: <2767969b94fd66db1fb0fc13b5783ae65b7deb2f.camel@perches.com> (raw)
In-Reply-To: <CAMpxmJU0C84DjPmqmWvPgv0zwgGLhkpKLRDuKkZHAa=wi+LvBA@mail.gmail.com>
On Tue, 2020-10-27 at 17:58 +0100, Bartosz Golaszewski wrote:
> On Tue, Oct 27, 2020 at 5:50 PM Joe Perches <joe@perches.com> wrote:
> >
> > On Tue, 2020-10-27 at 11:28 -0400, Michael S. Tsirkin wrote:
> > > On Tue, Oct 27, 2020 at 01:17:20PM +0100, Bartosz Golaszewski wrote:
> > > > From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> > > >
> > > > Use the helper that checks for overflows internally instead of manually
> > > > calculating the size of the new array.
> > > >
> > > > Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> > >
> > > No problem with the patch, it does introduce some symmetry in the code.
> >
> > Perhaps more symmetry by using kmemdup
> > ---
> > drivers/vhost/vringh.c | 23 ++++++++++-------------
> > 1 file changed, 10 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
> > index 8bd8b403f087..99222a3651cd 100644
> > --- a/drivers/vhost/vringh.c
> > +++ b/drivers/vhost/vringh.c
> > @@ -191,26 +191,23 @@ static int move_to_indirect(const struct vringh *vrh,
> > static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp)
> > {
> > struct kvec *new;
> > - unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2;
> > + size_t new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2;
> > + size_t size;
> >
> > if (new_num < 8)
> > new_num = 8;
> >
> > - flag = (iov->max_num & VRINGH_IOV_ALLOCATED);
> > - if (flag)
> > - new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp);
> > - else {
> > - new = kmalloc_array(new_num, sizeof(struct iovec), gfp);
> > - if (new) {
> > - memcpy(new, iov->iov,
> > - iov->max_num * sizeof(struct iovec));
> > - flag = VRINGH_IOV_ALLOCATED;
> > - }
> > - }
> > + if (unlikely(check_mul_overflow(new_num, sizeof(struct iovec), &size)))
> > + return -ENOMEM;
> > +
>
> The whole point of using helpers such as kmalloc_array() is not doing
> these checks manually.
Tradeoffs for in readability for overflow and not mistyping or doing
the multiplication of iov->max_num * sizeof(struct iovec) twice.
Just fyi:
the realloc doesn't do a multiplication overflow test as written so the
suggestion is slightly more resistant to defect.
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next prev parent reply other threads:[~2020-10-27 17:08 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-27 12:17 [PATCH 0/8] slab: provide and use krealloc_array() Bartosz Golaszewski
2020-10-27 12:17 ` [PATCH 1/8] mm: slab: provide krealloc_array() Bartosz Golaszewski
2020-10-27 18:20 ` Vlastimil Babka
2020-10-28 8:47 ` Mike Rapoport
2020-10-27 12:17 ` [PATCH 2/8] ALSA: pcm: use krealloc_array() Bartosz Golaszewski
2020-10-27 12:39 ` Takashi Iwai
2020-10-27 12:17 ` [PATCH 3/8] vhost: vringh: " Bartosz Golaszewski
2020-10-27 15:28 ` Michael S. Tsirkin
2020-10-27 16:50 ` Joe Perches
2020-10-27 16:58 ` Bartosz Golaszewski
2020-10-27 17:08 ` Joe Perches [this message]
2020-10-27 18:00 ` Bartosz Golaszewski
2020-10-27 12:17 ` [PATCH 4/8] pinctrl: " Bartosz Golaszewski
2020-10-27 12:17 ` [PATCH 5/8] edac: ghes: " Bartosz Golaszewski
2020-10-27 18:25 ` Borislav Petkov
2020-10-27 12:17 ` [PATCH 6/8] drm: atomic: " Bartosz Golaszewski
2020-10-27 19:19 ` Daniel Vetter
2020-10-27 12:17 ` [PATCH 7/8] hwtracing: intel: " Bartosz Golaszewski
2020-10-27 12:17 ` [PATCH 8/8] dma-buf: " Bartosz Golaszewski
2020-10-27 12:21 ` Christian König
2020-11-05 10:52 ` [PATCH 0/8] slab: provide and " Linus Walleij
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