Re: [PATCH] btf: Protect BTF_KIND_INFO against invalid kind

[David Faust <david.faust@oracle.com>]

On 8/7/24 10:19, Will Hawkins wrote:
> On Mon, Jul 29, 2024 at 2:14 PM David Faust <david.faust@oracle.com> wrote:
>>
>>
>> On 7/29/24 07:42, Will Hawkins wrote:
>>> If the user provides a kind value that is more than 5 bits, the
>>> BTF_KIND_INFO macro would emit incorrect values for info (by clobbering
>>> values of the kind flag).
>>>
>>> Tested on x86_64-redhat-linux.
>>
>> OK, thanks.
> 
> Just let me know if there is anything else that you need from me!
> Will

I just checked this in on your behalf.  Apologies for the delay.
Thanks!

> 
>>
>>>
>>> include/ChangeLog:
>>>
>>>       * btf.h (BTF_TYPE_INFO): Protect against user providing invalid
>>>         kind.
>>>
>>> Signed-off-by: Will Hawkins <hawkinsw@obs.cr>
>>> ---
>>>
>>> Notes:
>>>      I have a small out-of-tree test but was not sure whether a) it should
>>>                be included and/or b) where it should be included. If you would
>>>                like me to include it, please just let me know where it should go!
>>>
>>>  include/btf.h | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/include/btf.h b/include/btf.h
>>> index 3f45ffb0b6b..0c3e1a1cf51 100644
>>> --- a/include/btf.h
>>> +++ b/include/btf.h
>>> @@ -82,7 +82,7 @@ struct btf_type
>>>    };
>>>  };
>>>
>>> -/* The folloing macros access the information encoded in btf_type.info.  */
>>> +/* The following macros access the information encoded in btf_type.info.  */
>>>  /* Type kind. See below.  */
>>>  #define BTF_INFO_KIND(info)  (((info) >> 24) & 0x1f)
>>>  /* Number of entries of variable length data following certain type kinds.
>>> @@ -95,7 +95,7 @@ struct btf_type
>>>
>>>  /* Encoding for struct btf_type.info.  */
>>>  #define BTF_TYPE_INFO(kind, kflag, vlen) \
>>> -  ((((kflag) ? 1 : 0 ) << 31) | ((kind) << 24) | ((vlen) & 0xffff))
>>> +  ((((kflag) ? 1 : 0 ) << 31) | ((kind & 0x1f) << 24) | ((vlen) & 0xffff))
>>>
>>>  #define BTF_KIND_UNKN                0       /* Unknown or invalid.  */
>>>  #define BTF_KIND_INT         1       /* Integer.  */