linux-kernel - Re: [PATCH] uio: fix is_source param for check_copy_size() in copy_to_iter

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Date:   Wed, 12 Sep 2018 14:51:53 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Dave Jiang <dave.jiang@...el.com>,
        Vishal L Verma <vishal.l.verma@...el.com>,
        "Du, Fan" <fan.du@...el.com>,
        linux-nvdimm <linux-nvdimm@...ts.01.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Al Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] uio: fix is_source param for check_copy_size() in copy_to_iter_mcsafe()

On Wed, Sep 12, 2018 at 12:48 AM, Greg KH <gregkh@...uxfoundation.org> wrote:
> On Wed, Sep 05, 2018 at 01:31:40PM -0700, Dave Jiang wrote:
>> copy_to_iter_mcsafe() is passing in the is_source parameter as "false"
>> to check_copy_size(). This is different than what copy_to_iter() does.
>> Also, the addr parameter passed to check_copy_size() is the source so
>> therefore we should be passing in "true" instead.
>>
>> Fixes: 8780356ef630 ("x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()")
>> Cc: Fan Du <fan.du@...el.com>
>> Reported-by: Wenwei Tao <wenwei.tww@...baba-inc.com>
>> Signed-off-by: Dave Jiang <dave.jiang@...el.com>
>> Reviewed-by: Vishal Verma <vishal.l.verma@...el.com>
>> Cc: stable <stable@...r.kernel.org>
>> ---
>>  include/linux/uio.h |    2 +-
>
> I am not the maintainer of this file, sorry, please work with the -mm
> developers for this.

Likely this is get_maintainer.pl's fault:

$ ./scripts/get_maintainer.pl  -f include/linux/uio.h
Greg Kroah-Hartman <gregkh@...uxfoundation.org> (maintainer:USERSPACE I/O (UIO))
linux-kernel@...r.kernel.org (open list)

Maybe a MAINTAINERS update like the following is warranted, because I
don't think -mm developers are right either, Al seems to be authority
on iov_iter apis:

diff --git a/MAINTAINERS b/MAINTAINERS
index d870cb57c887..0018e19b4d8e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15344,13 +15344,18 @@ F:    arch/x86/um/
 F:     fs/hostfs/
 F:     fs/hppfs/

+USERSPACE ACCESS (uaccess, copy_{to,from}_iter)
+M:     Alexander Viro <viro@...iv.linux.org.uk>
+S:     Maintained
+F:     include/linux/uio*.h
+F:     lib/iov_iter.c
+
 USERSPACE I/O (UIO)
 M:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
 S:     Maintained
 T:     git git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
 F:     Documentation/driver-api/uio-howto.rst
 F:     drivers/uio/
-F:     include/linux/uio*.h

 UTIL-LINUX PACKAGE
 M:     Karel Zak <kzak@...hat.com>

---

In any event, the patch in question is a trivial one liner, I feel
confident sending it along to Linus with some other pending fixes.