From: Christoph Hellwig <hch@infradead.org>
To: Dave Jones <davej@codemonkey.org.uk>,
Christoph Hellwig <hch@infradead.org>,
Kees Cook <keescook@chromium.org>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: sg_io HARDENED_USERCOPY_PAGESPAN trace
Date: Fri, 30 Dec 2016 05:37:12 -0800 [thread overview]
Message-ID: <20161230133712.GA27511@infradead.org> (raw)
In-Reply-To: <20161229154351.6zrxuagi62pga6mt@codemonkey.org.uk>
On Thu, Dec 29, 2016 at 10:43:51AM -0500, Dave Jones wrote:
> On Wed, Dec 28, 2016 at 11:56:42PM -0800, Christoph Hellwig wrote:
> > On Wed, Dec 28, 2016 at 04:40:16PM -0500, Dave Jones wrote:
> > > sg_io+0x113/0x470
> >
> > Can you resolve that to a source line using a gdb?
>
> It's the copy_from_user in an inlined copy of blk_fill_sghdr_rq.
That must be this line right at the beginning of blk_fill_sghdr_rq
if (copy_from_user(rq->cmd, hdr->cmdp, hdr->cmd_len))
return -EFAULT;
We're copying the SCSI CDB from the userspace pointer inside the hdr
we copied earlier into the request.
req->cmd is set to req->__cmd which is a u8 array with 16 members in
struct request by default, but if hdr->cmd_len is bigger than BLK_MAX_CDB
(16) we do a separate allocation for it in the caller:
if (hdr->cmd_len > BLK_MAX_CDB) {
rq->cmd = kzalloc(hdr->cmd_len, GFP_KERNEL);
if (!rq->cmd)
goto out_put_request;
}
so I'm not really sure what the problem here could be.
next prev parent reply other threads:[~2016-12-30 13:37 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-28 21:40 sg_io HARDENED_USERCOPY_PAGESPAN trace Dave Jones
2016-12-29 7:56 ` Christoph Hellwig
2016-12-29 15:43 ` Dave Jones
2016-12-30 13:37 ` Christoph Hellwig [this message]
2016-12-30 15:01 ` Dave Jones
2016-12-30 15:10 ` Christoph Hellwig
2017-01-03 21:48 ` Kees Cook
2017-01-08 9:44 ` Christoph Hellwig
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