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Re: [Xen-devel] [PATCH] xen/privcmd: fix static checker warning
- To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>, Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>
- From: Juergen Gross <jgross@xxxxxxxx>
- Date: Thu, 7 Jun 2018 16:03:05 +0200
- Autocrypt: addr=jgross@xxxxxxxx; prefer-encrypt=mutual; keydata= xsBNBFOMcBYBCACgGjqjoGvbEouQZw/ToiBg9W98AlM2QHV+iNHsEs7kxWhKMjrioyspZKOB ycWxw3ie3j9uvg9EOB3aN4xiTv4qbnGiTr3oJhkB1gsb6ToJQZ8uxGq2kaV2KL9650I1SJve dYm8Of8Zd621lSmoKOwlNClALZNew72NjJLEzTalU1OdT7/i1TXkH09XSSI8mEQ/ouNcMvIJ NwQpd369y9bfIhWUiVXEK7MlRgUG6MvIj6Y3Am/BBLUVbDa4+gmzDC9ezlZkTZG2t14zWPvx XP3FAp2pkW0xqG7/377qptDmrk42GlSKN4z76ELnLxussxc7I2hx18NUcbP8+uty4bMxABEB AAHNHkp1ZXJnZW4gR3Jvc3MgPGpncm9zc0BzdXNlLmRlPsLAeQQTAQIAIwUCU4xw6wIbAwcL CQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJELDendYovxMvi4UH/Ri+OXlObzqMANruTd4N zmVBAZgx1VW6jLc8JZjQuJPSsd/a+bNr3BZeLV6lu4Pf1Yl2Log129EX1KWYiFFvPbIiq5M5 kOXTO8Eas4CaScCvAZ9jCMQCgK3pFqYgirwTgfwnPtxFxO/F3ZcS8jovza5khkSKL9JGq8Nk czDTruQ/oy0WUHdUr9uwEfiD9yPFOGqp4S6cISuzBMvaAiC5YGdUGXuPZKXLpnGSjkZswUzY d9BVSitRL5ldsQCg6GhDoEAeIhUC4SQnT9SOWkoDOSFRXZ+7+WIBGLiWMd+yKDdRG5RyP/8f 3tgGiB6cyuYfPDRGsELGjUaTUq3H2xZgIPfOwE0EU4xwFgEIAMsx+gDjgzAY4H1hPVXgoLK8 B93sTQFN9oC6tsb46VpxyLPfJ3T1A6Z6MVkLoCejKTJ3K9MUsBZhxIJ0hIyvzwI6aYJsnOew cCiCN7FeKJ/oA1RSUemPGUcIJwQuZlTOiY0OcQ5PFkV5YxMUX1F/aTYXROXgTmSaw0aC1Jpo w7Ss1mg4SIP/tR88/d1+HwkJDVW1RSxC1PWzGizwRv8eauImGdpNnseneO2BNWRXTJumAWDD pYxpGSsGHXuZXTPZqOOZpsHtInFyi5KRHSFyk2Xigzvh3b9WqhbgHHHE4PUVw0I5sIQt8hJq 5nH5dPqz4ITtCL9zjiJsExHuHKN3NZsAEQEAAcLAXwQYAQIACQUCU4xwFgIbDAAKCRCw3p3W KL8TL0P4B/9YWver5uD/y/m0KScK2f3Z3mXJhME23vGBbMNlfwbr+meDMrJZ950CuWWnQ+d+ Ahe0w1X7e3wuLVODzjcReQ/v7b4JD3wwHxe+88tgB9byc0NXzlPJWBaWV01yB2/uefVKryAf AHYEd0gCRhx7eESgNBe3+YqWAQawunMlycsqKa09dBDL1PFRosF708ic9346GLHRc6Vj5SRA UTHnQqLetIOXZm3a2eQ1gpQK9MmruO86Vo93p39bS1mqnLLspVrL4rhoyhsOyh0Hd28QCzpJ wKeHTd0MAWAirmewHXWPco8p1Wg+V+5xfZzuQY0f4tQxvOpXpt4gQ1817GQ5/Ed/wsDtBBgB CAAgFiEEhRJncuj2BJSl0Jf3sN6d1ii/Ey8FAlrd8NACGwIAgQkQsN6d1ii/Ey92IAQZFggA HRYhBFMtsHpB9jjzHji4HoBcYbtP2GO+BQJa3fDQAAoJEIBcYbtP2GO+TYsA/30H/0V6cr/W V+J/FCayg6uNtm3MJLo4rE+o4sdpjjsGAQCooqffpgA+luTT13YZNV62hAnCLKXH9n3+ZAgJ RtAyDWk1B/0SMDVs1wxufMkKC3Q/1D3BYIvBlrTVKdBYXPxngcRoqV2J77lscEvkLNUGsu/z W2pf7+P3mWWlrPMJdlbax00vevyBeqtqNKjHstHatgMZ2W0CFC4hJ3YEetuRBURYPiGzuJXU pAd7a7BdsqWC4o+GTm5tnGrCyD+4gfDSpkOT53S/GNO07YkPkm/8J4OBoFfgSaCnQ1izwgJQ jIpcG2fPCI2/hxf2oqXPYbKr1v4Z1wthmoyUgGN0LPTIm+B5vdY82wI5qe9uN6UOGyTH2B3p hRQUWqCwu2sqkI3LLbTdrnyDZaixT2T0f4tyF5Lfs+Ha8xVMhIyzNb1byDI5FKCb
- Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Dan Carpenter <dan.carpenter@xxxxxxxxxx>
- Delivery-date: Thu, 07 Jun 2018 14:03:13 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
- Openpgp: preference=signencrypt
On 07/06/18 13:23, Paul Durrant wrote:
>> -----Original Message-----
>> From: Andrew Cooper
>> Sent: 07 June 2018 11:28
>> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>; xen-devel@xxxxxxxxxxxxxxxxxxxx;
>> linux-kernel@xxxxxxxxxxxxxxx
>> Cc: Juergen Gross <jgross@xxxxxxxx>; Boris Ostrovsky
>> <boris.ostrovsky@xxxxxxxxxx>; Dan Carpenter
>> <dan.carpenter@xxxxxxxxxx>
>> 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.carpenter@xxxxxxxxxx>
>>> Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
>>
>> 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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