Message-ID: <0e6e66f7368621128a810bb604eab229dd279187.camel@kernel.org>
Subject: Re: Commit f980d055a0f858d73d9467bb0b570721bbfcdfb8 causes a
 regression
From:   Jeff Layton <jlayton@kernel.org>
To:     Tim Gardner <tim.gardner@canonical.com>, len.baker@gmx.com
Cc:     pc@cjr.nz, stfrench@microsoft.com,
        Kamal Mostafa <Kamal.Mostafa@canonical.com>,
        linux-cifs@vger.kernel.org,
        samba-technical <samba-technical@lists.samba.org>,
        LKML <linux-kernel@vger.kernel.org>, stable@vger.kernel.org
Date:   Mon, 29 Nov 2021 11:01:27 -0500
In-Reply-To: <a8b2287b-c459-2169-fbf4-31f3065e0897@canonical.com>
References: <a8b2287b-c459-2169-fbf4-31f3065e0897@canonical.com>
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On Mon, 2021-11-29 at 08:35 -0700, Tim Gardner wrote:
> Hi Len,
> 
> I have a report (https://bugs.launchpad.net/bugs/1952094) that commit 
> f980d055a0f858d73d9467bb0b570721bbfcdfb8 ("CIFS: Fix a potencially 
> linear read overflow") causes a regression as a stable backport in a 5.4 
> based kernel. I don't know if this regression exists in tip as well, or 
> if it is unique to the backported environment. I suspect, given the 
> content of the patch, that it is generic. As such, it has been 
> backported to a number of stable releases:
> 
> linux-4.4.y.txt:0955df2d9bf4857e3e2287e3028903e6cec06c30
> linux-4.9.y.txt:8878af780747f498551b7d360cae61b415798f18
> linux-4.14.y.txt:20967547ffc6039f17c63a1c24eb779ee166b245
> linux-4.19.y.txt:bea655491daf39f1934a71bf576bf3499092d3a4
> linux-5.4.y.txt:b444064a0e0ef64491b8739a9ae05a952b5f8974
> linux-5.10.y.txt:6c4857203ffa36918136756a889b12c5864bc4ad
> linux-5.13.y.txt:9bffe470e9b537075345406512df01ca2188b725
> linux-5.14.y.txt:c41dd61c86482ab34f6f039b13296308018fd99b
> 
> Could this be an off-by-one issue if the source string is full length ?
> 
> rtg

Maybe? But it doesn't seem to be that long. The error message evidently
says:

    "CIFS VFS: CIFS mount error: iocharset utf8 not found"

The iocharset string ("utf8" here) usually gets set in the mount string
and then we just pass that string to load_nls().

The patch you're pointing out though doesn't seem to be involved in any
of that. It sounds like something else is wrong. I'd validate that that
patch was applied correctly, and get more details about what this guy is
doing.

g/l!
-- 
Jeff Layton <jlayton@kernel.org>