On 07/06/18 13:23, Paul Durrant wrote:
>> -----Original Message-----
>> From: Andrew Cooper
>> Sent: 07 June 2018 11:28
>> To: Paul Durrant <paul.durr...@citrix.com>; xen-devel@lists.xenproject.org;
>> linux-ker...@vger.kernel.org
>> Cc: Juergen Gross <jgr...@suse.com>; Boris Ostrovsky
>> <boris.ostrov...@oracle.com>; Dan Carpenter
>> <dan.carpen...@oracle.com>
>> Subject: Re: [Xen-devel] [PATCH] xen/privcmd: fix static checker warning
>>
>> On 07/06/18 11:21, Paul Durrant wrote:
>>> Commit 3ad0876554ca ("xen/privcmd: add
>> IOCTL_PRIVCMD_MMAP_RESOURCE")
>>> introduced a static checker warning:
>>>
>>> drivers/xen/privcmd.c:827 privcmd_ioctl_mmap_resource()
>>> warn: passing casted pointer 'pfns' to 'xen_remap_domain_mfn_array()'
>>> 64 vs 32.
>>>
>>> caused by this cast:
>>>
>>> 827 num = xen_remap_domain_mfn_array(vma,
>>> 828 kdata.addr & PAGE_MASK,
>>> 829 pfns, kdata.num, (int *)pfns,
>>> ^^^^^^^^^^^
>>>
>>> The reason for the cast is that xen_remap_domain_mfn_array() requires
>> an
>>> array of ints to store error codes. It is actually safe to re-use the
>>> pfns array for this purpose but it does look odd (as well as leading to
>>> the warning). It would also be easy for a future implementation change
>>> to make this re-use unsafe so this patch modifies privcmd to use a
>>> separately allocated array for error codes.
>>>
>>> Reported-by: Dan Carpenter <dan.carpen...@oracle.com>
>>> Signed-off-by: Paul Durrant <paul.durr...@citrix.com>
>>
>> It may be safe to reuse pfns[] as the storage space for the errs array,
>> but code is incorrect when sizeof(pfn) != sizeof(int). In such a case,
>> you skip over every other err, and second half of pfns[] is junk from
>> the point of view of the errs loop.
>>
>
> Yep, that is indeed what happens without this patch.
Can you please update the commit message accordingly?
Juergen
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