From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Peter Xu <peterx@redhat.com>,
"Zengtao (B)" <prime.zeng@hisilicon.com>,
Cornelia Huck <cohuck@redhat.com>,
Kevin Tian <kevin.tian@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Giovanni Cabiddu <giovanni.cabiddu@intel.com>,
Michel Lespinasse <walken@google.com>,
Jann Horn <jannh@google.com>, Max Gurtovoy <mgurtovoy@nvidia.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Linuxarm <linuxarm@huawei.com>
Subject: Re: [PATCH] vfio/pci: make the vfio_pci_mmap_fault reentrant
Date: Tue, 9 Mar 2021 19:41:27 -0400 [thread overview]
Message-ID: <20210309234127.GM2356281@nvidia.com> (raw)
In-Reply-To: <20210309122607.0b68fb9b@omen.home.shazbot.org>
On Tue, Mar 09, 2021 at 12:26:07PM -0700, Alex Williamson wrote:
> In the new series, I think the fault handler becomes (untested):
>
> static vm_fault_t vfio_pci_mmap_fault(struct vm_fault *vmf)
> {
> struct vm_area_struct *vma = vmf->vma;
> struct vfio_pci_device *vdev = vma->vm_private_data;
> unsigned long base_pfn, pgoff;
> vm_fault_t ret = VM_FAULT_SIGBUS;
>
> if (vfio_pci_bar_vma_to_pfn(vma, &base_pfn))
> return ret;
>
> pgoff = (vmf->address - vma->vm_start) >> PAGE_SHIFT;
I don't think this math is completely safe, it needs to parse the
vm_pgoff..
I'm worried userspace could split/punch/mangle a VMA using
munmap/mremap/etc/etc in a way that does update the pg_off but is
incompatible with the above.
Jason
next prev parent reply other threads:[~2021-03-09 23:42 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-08 11:11 [PATCH] vfio/pci: make the vfio_pci_mmap_fault reentrant Zeng Tao
2021-03-08 20:21 ` Alex Williamson
2021-03-08 22:56 ` Peter Xu
2021-03-09 3:49 ` 答复: " Zengtao (B)
2021-03-09 12:46 ` Jason Gunthorpe
2021-03-09 15:29 ` Alex Williamson
2021-03-09 16:40 ` Jason Gunthorpe
2021-03-09 18:47 ` Peter Xu
2021-03-09 19:26 ` Alex Williamson
2021-03-09 19:48 ` Peter Xu
2021-03-09 20:11 ` Alex Williamson
2021-03-09 21:00 ` Peter Xu
2021-03-09 21:43 ` Alex Williamson
2021-03-09 19:56 ` Alex Williamson
2021-03-09 23:45 ` Jason Gunthorpe
2021-03-10 6:23 ` Alex Williamson
2021-03-09 23:41 ` Jason Gunthorpe [this message]
2021-03-10 6:08 ` Alex Williamson
2021-03-11 3:32 ` 答复: " Zengtao (B)
2021-03-08 23:43 ` Jason Gunthorpe
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