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From:   Dan Williams <dan.j.williams@intel.com>
Date:   Wed, 24 Mar 2021 11:54:59 -0700
Message-ID: <CAPcyv4gQzTZHX+fO45V+U4onhOA-H-U6E+GeqySdxHvNcqYeUg@mail.gmail.com>
Subject: Re: [PATCH] cxl/mem: Force array size of mem_commands[] to CXL_MEM_COMMAND_ID_MAX
To:     Robert Richter <rrichter@amd.com>
Cc:     Alison Schofield <alison.schofield@intel.com>,
        Vishal Verma <vishal.l.verma@intel.com>,
        Ira Weiny <ira.weiny@intel.com>,
        Ben Widawsky <ben.widawsky@intel.com>,
        linux-cxl@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Wed, Mar 24, 2021 at 7:17 AM Robert Richter <rrichter@amd.com> wrote:
>
> Typically the mem_commands[] array is in sync with 'enum { CXL_CMDS }'.
> Current code works well.
>
> However, the array size of mem_commands[] may not strictly be the same
> as CXL_MEM_COMMAND_ID_MAX. E.g. if a new CXL_CMD() is added that is
> guarded by #ifdefs, the array could be shorter. This could lead then
> further to an out-of-bounds array access in cxl_validate_cmd_from_user().

Good catch.

>
> Fix this by forcing the array size to CXL_MEM_COMMAND_ID_MAX. This
> also adds range checks for array items in mem_commands[] at compile
> time.
>
> Signed-off-by: Robert Richter <rrichter@amd.com>

Thanks, applied.