From: Felipe Balbi <balbi@kernel.org>
To: John Keeping <john@metanate.com>
Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Vincent Pelletier <plr.vincent@gmail.com>,
Jim Lin <jilin@nvidia.com>,
Janusz Dziedzic <januszx.dziedzic@linux.intel.com>,
stable@vger.kernel.org
Subject: Re: [PATCH] usb: f_fs: Drop check on Reserved1 field on OS_DESC_EXT_COMPAT
Date: Mon, 13 Nov 2017 12:57:21 +0200 [thread overview]
Message-ID: <877euue99q.fsf@linux.intel.com> (raw)
In-Reply-To: <20171110183408.4fc19913.john@metanate.com>
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Hi,
John Keeping <john@metanate.com> writes:
> On Fri, 10 Nov 2017 12:40:39 +0200, Felipe Balbi wrote:
>
>> John Keeping <john@metanate.com> writes:
>> > This check has gone through several incompatible variations in commits
>> > 53642399aa71 ("usb: gadget: f_fs: Fix wrong check on reserved1 of
>> > OS_DESC_EXT_COMPAT"), 354bc45bf329 ("usb: gadget: f_fs: Fix ExtCompat
>> > descriptor validation") and 3ba534df815f ("Revert "usb: gadget: f_fs:
>> > Fix ExtCompat descriptor validation"") after initially being introduced
>> > in commit f0175ab51993 ("usb: gadget: f_fs: OS descriptors support").
>> >
>> > The various changes make it impossible for a single userspace
>> > implementation to work with different kernel versions, so let's just
>> > drop the condition to avoid breaking userspace.
>> >
>> > Fixes: 53642399aa71 ("usb: gadget: f_fs: Fix wrong check on reserved1 of OS_DESC_EXT_COMPAT")
>> > Cc: stable@vger.kernel.org # v4.7+
>> > Signed-off-by: John Keeping <john@metanate.com>
>> > ---
>> > drivers/usb/gadget/function/f_fs.c | 3 +--
>> > 1 file changed, 1 insertion(+), 2 deletions(-)
>> >
>> > diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c
>> > index 652397eda6d6..0d9962834345 100644
>> > --- a/drivers/usb/gadget/function/f_fs.c
>> > +++ b/drivers/usb/gadget/function/f_fs.c
>> > @@ -2282,8 +2282,7 @@ static int __ffs_data_do_os_desc(enum ffs_os_desc_type type,
>> > int i;
>> >
>> > if (len < sizeof(*d) ||
>> > - d->bFirstInterfaceNumber >= ffs->interfaces_count ||
>> > - !d->Reserved1)
>> > + d->bFirstInterfaceNumber >= ffs->interfaces_count)
>> > return -EINVAL;
>> > for (i = 0; i < ARRAY_SIZE(d->Reserved2); ++i)
>> > if (d->Reserved2[i])
>>
>> Sorry, but no. We want to be compliant with the specification. If there
>> are older still-maintained stable trees which are not working, we need
>> to backport a fix to them, but we're not allowing uncompliant
>> implementations.
>
> Aren't we allowing non-compliant implementations now? The spec says the
> value must be 1 but since v4.7 this code has allowed all non-zero
> values.
Good point. Then how about we just force the value to 1 in f_fs.c and
remove the check?
--
balbi
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next prev parent reply other threads:[~2017-11-13 10:57 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-09 16:34 [PATCH] usb: f_fs: Drop check on Reserved1 field on OS_DESC_EXT_COMPAT John Keeping
2017-11-10 10:40 ` Felipe Balbi
2017-11-10 18:34 ` John Keeping
2017-11-13 10:57 ` Felipe Balbi [this message]
2017-11-13 18:19 ` John Keeping
2017-11-27 11:34 ` Felipe Balbi
2017-11-27 18:15 ` [PATCH v2] usb: f_fs: Force Reserved1=1 in OS_DESC_EXT_COMPAT John Keeping
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