From: Yi Zhang <yi.z.zhang@linux.intel.com> To: Dan Williams <dan.j.williams@intel.com> Cc: "Zhang, Yu C" <yu.c.zhang@intel.com>, linux-nvdimm <linux-nvdimm@lists.01.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, zwisler@kernel.org, Jan Kara <jack@suse.cz>, "Zhang, Yi Z" <yi.z.zhang@intel.com> Subject: Re: [PATCH V2 1/1] device-dax: check for vma range while dax_mmap. Date: Thu, 13 Dec 2018 14:12:40 +0800 [thread overview] Message-ID: <20181213061239.GA43404@tiger-server> (raw) In-Reply-To: <CAPcyv4gZ8WBhUZkoUd1m6bCrtKW0EmfWfCtpGULvjfM=yJ9_sg@mail.gmail.com> On 2018-12-10 at 16:10:31 -0800, Dan Williams wrote: > On Tue, Aug 21, 2018 at 12:38 AM Yi Zhang <yi.z.zhang@linux.intel.com> wrote: > > > > On 2018-08-20 at 12:50:31 -0700, Dave Jiang wrote: > > > > > > > > > On 08/20/2018 10:53 AM, Verma, Vishal L wrote: > > > > > > > > On Mon, 2018-08-13 at 20:02 +0800, Zhang Yi wrote: > > > >> This patch prevents a user mapping an illegal vma range that is larger > > > >> than a dax device physical resource. > > > >> > > > >> When qemu maps the dax device for virtual nvdimm's backend device, the > > > >> v-nvdimm label area is defined at the end of mapped range. By using an > > > >> illegal size that exceeds the range of the device dax, it will trigger a > > > >> fault with qemu. > > > >> > > > >> Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com> > > > >> --- > > > >> drivers/dax/device.c | 29 +++++++++++++++++++++++++++++ > > > >> 1 file changed, 29 insertions(+) > > > >> > > > > > > > > Looks good to me: > > > > Reviewed-by: Vishal Verma <vishal.l.verma@intel.com> > > > > > > Applied. > > Thanks Dava and Vishal's kindly review. Thank you. > > So, it turns out this patch did not get merged for 4.20. I fumbled it > when returning from vacation. However, I'm not sure it is needed. As > long as attempts to access the out-of-range capacity results in SIGBUS > then the implementation is correct. This is similar to the case where > a file is truncated after the vma is established. That size is > validated at fault time. The problem is that we didn't get the fault at we initial the mapping until attempt to access it, then qemu will failed unexpect without any output, I think is is better to mention user that we are starting at a illegal size, but not faulting at an uncertained time. > > Could you be clearer about why this is a problem? The fault sounds > like the correct result. > _______________________________________________ > Linux-nvdimm mailing list > Linux-nvdimm@lists.01.org > https://lists.01.org/mailman/listinfo/linux-nvdimm _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm
WARNING: multiple messages have this Message-ID (diff)
From: Yi Zhang <yi.z.zhang@linux.intel.com> To: Dan Williams <dan.j.williams@intel.com> Cc: Dave Jiang <dave.jiang@intel.com>, Vishal L Verma <vishal.l.verma@intel.com>, "Zhang, Yu C" <yu.c.zhang@intel.com>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-nvdimm <linux-nvdimm@lists.01.org>, zwisler@kernel.org, Jan Kara <jack@suse.cz>, "Zhang, Yi Z" <yi.z.zhang@intel.com> Subject: Re: [PATCH V2 1/1] device-dax: check for vma range while dax_mmap. Date: Thu, 13 Dec 2018 14:12:40 +0800 [thread overview] Message-ID: <20181213061239.GA43404@tiger-server> (raw) In-Reply-To: <CAPcyv4gZ8WBhUZkoUd1m6bCrtKW0EmfWfCtpGULvjfM=yJ9_sg@mail.gmail.com> On 2018-12-10 at 16:10:31 -0800, Dan Williams wrote: > On Tue, Aug 21, 2018 at 12:38 AM Yi Zhang <yi.z.zhang@linux.intel.com> wrote: > > > > On 2018-08-20 at 12:50:31 -0700, Dave Jiang wrote: > > > > > > > > > On 08/20/2018 10:53 AM, Verma, Vishal L wrote: > > > > > > > > On Mon, 2018-08-13 at 20:02 +0800, Zhang Yi wrote: > > > >> This patch prevents a user mapping an illegal vma range that is larger > > > >> than a dax device physical resource. > > > >> > > > >> When qemu maps the dax device for virtual nvdimm's backend device, the > > > >> v-nvdimm label area is defined at the end of mapped range. By using an > > > >> illegal size that exceeds the range of the device dax, it will trigger a > > > >> fault with qemu. > > > >> > > > >> Signed-off-by: Zhang Yi <yi.z.zhang@linux.intel.com> > > > >> --- > > > >> drivers/dax/device.c | 29 +++++++++++++++++++++++++++++ > > > >> 1 file changed, 29 insertions(+) > > > >> > > > > > > > > Looks good to me: > > > > Reviewed-by: Vishal Verma <vishal.l.verma@intel.com> > > > > > > Applied. > > Thanks Dava and Vishal's kindly review. Thank you. > > So, it turns out this patch did not get merged for 4.20. I fumbled it > when returning from vacation. However, I'm not sure it is needed. As > long as attempts to access the out-of-range capacity results in SIGBUS > then the implementation is correct. This is similar to the case where > a file is truncated after the vma is established. That size is > validated at fault time. The problem is that we didn't get the fault at we initial the mapping until attempt to access it, then qemu will failed unexpect without any output, I think is is better to mention user that we are starting at a illegal size, but not faulting at an uncertained time. > > Could you be clearer about why this is a problem? The fault sounds > like the correct result. > _______________________________________________ > Linux-nvdimm mailing list > Linux-nvdimm@lists.01.org > https://lists.01.org/mailman/listinfo/linux-nvdimm
next prev parent reply other threads:[~2018-12-13 6:12 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-08-13 12:02 [PATCH V2 1/1] device-dax: check for vma range while dax_mmap Zhang Yi 2018-08-13 12:02 ` Zhang Yi 2018-08-20 17:53 ` Verma, Vishal L 2018-08-20 17:53 ` Verma, Vishal L 2018-08-20 19:50 ` Dave Jiang 2018-08-20 19:50 ` Dave Jiang 2018-08-21 16:16 ` Yi Zhang 2018-08-21 16:16 ` Yi Zhang 2018-12-11 0:10 ` Dan Williams 2018-12-11 0:10 ` Dan Williams 2018-12-13 6:12 ` Yi Zhang [this message] 2018-12-13 6:12 ` Yi Zhang 2018-12-20 1:41 ` Dan Williams 2018-12-20 1:41 ` Dan Williams
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