linux-kernel - Re: [PATCH 2/5] 9p: virtio: fix unlikely null pointer deref in handle

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Date:   Tue, 2 May 2023 17:28:10 +0200
From:   Simon Horman <simon.horman@...igine.com>
To:     Dominique Martinet <asmadeus@...ewreck.org>
Cc:     Eric Van Hensbergen <ericvh@...il.com>,
        Latchesar Ionkov <lucho@...kov.net>,
        Christian Schoenebeck <linux_oss@...debyte.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, v9fs@...ts.linux.dev,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 2/5] 9p: virtio: fix unlikely null pointer deref in
 handle_rerror

On Thu, Apr 27, 2023 at 08:23:35PM +0900, Dominique Martinet wrote:
> handle_rerror can dereference the pages pointer, but it is not
> necessarily set for small payloads.
> In practice these should be filtered out by the size check, but
> might as well double-check explicitly.
> 
> This fixes the following scan-build warnings:
> net/9p/trans_virtio.c:401:24: warning: Dereference of null pointer [core.NullDereference]
>                 memcpy_from_page(to, *pages++, offs, n);
>                                      ^~~~~~~~
> net/9p/trans_virtio.c:406:23: warning: Dereference of null pointer (loaded from variable 'pages') [core.NullDereference]
>         memcpy_from_page(to, *pages, offs, size);
>                              ^~~~~~
> 
> Signed-off-by: Dominique Martinet <asmadeus@...ewreck.org>

Reviewed-by: Simon Horman <simon.horman@...igine.com>