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[80.230.85.71]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-46c221d93d8sm17353516f8f.23.2026.06.24.14.54.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jun 2026 14:54:15 -0700 (PDT) Date: Wed, 24 Jun 2026 17:54:13 -0400 From: "Michael S. Tsirkin" To: Yousef Alhouseen Cc: Jason Wang , Eugenio =?iso-8859-1?Q?P=E9rez?= , kvm@vger.kernel.org, virtualization@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] vhost/vdpa: reject overflowing PA map page counts on 32-bit Message-ID: <20260624175356-mutt-send-email-mst@kernel.org> References: Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Wed, Jun 24, 2026 at 02:51:53PM -0700, Yousef Alhouseen wrote: > vhost_vdpa_pa_map() adds the IOVA page offset to the user-controlled map > size before computing the number of pages to pin. On 32-bit systems, > where unsigned long is narrower than u64, that addition can overflow and > the code can pin and map fewer pages than the requested IOTLB range. > > Reject sizes that overflow the unsigned long page-count calculation. > And a Fixes: tag, please. > Signed-off-by: Yousef Alhouseen > --- > Changes in v2: > - Clarify that the overflow is on 32-bit systems. > - Drop the unrelated memlock check change. > > drivers/vhost/vdpa.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > index ac55275fa..38b28ed3d 100644 > --- a/drivers/vhost/vdpa.c > +++ b/drivers/vhost/vdpa.c > @@ -1102,6 +1102,7 @@ static int vhost_vdpa_pa_map(struct vhost_vdpa *v, > unsigned int gup_flags = FOLL_LONGTERM; > unsigned long npages, cur_base, map_pfn, last_pfn = 0; > unsigned long lock_limit, sz2pin, nchunks, i; > + unsigned long page_offset; > u64 start = iova; > long pinned; > int ret = 0; > @@ -1114,7 +1115,13 @@ static int vhost_vdpa_pa_map(struct vhost_vdpa *v, > if (perm & VHOST_ACCESS_WO) > gup_flags |= FOLL_WRITE; > > - npages = PFN_UP(size + (iova & ~PAGE_MASK)); > + page_offset = iova & ~PAGE_MASK; > + if (size > ULONG_MAX - page_offset) { > + ret = -EINVAL; > + goto free; > + } > + > + npages = PFN_UP(size + page_offset); > if (!npages) { > ret = -EINVAL; > goto free; > -- > 2.54.0