On 11/24/22 09:44, Simon Horman wrote:
> On Wed, Nov 23, 2022 at 10:23:37PM +0100, Ilya Maximets wrote:
>> The value is right-justified after the string parsing with
>> parse_int_string(), i.e. it is in BE byte order and aligned
>> to the right side of the array.
>>
>> For example, the 0x10011 value in a 4-byte field will look
>> like 0x00 0x01 0x00 0x11.
>>
>> However, value copy to the resulted ofpact is performed
>> from the start of the memory. So, in case the destination
>> size is smaller than the original field size, incorrect
>> part of the value will be copied.
>>
>> In the 0x00 0x01 0x00 0x11 example above, if the copy is
>> performed to a 3-byte field, the first 3 bytes will be
>> copied, which are 0x00 0x01 0x00 instead of 0x01 0x00 0x11.
>>
>> This leads to a problem where NXM_NX_REG3[0..16]=0x10011
>> turns into NXM_NX_REG3[0..16]=0x100 after the parsing.
>>
>> Fix that by offsetting the starting position to the size
>> difference in bytes similarly to how it is done in
>> learn_parse_load_immediate().
>>
>> While at it, changing &imm to imm.b in function calls that
>> expect byte arrays as an argument. The old way is technically
>> correct, but more error prone.
>>
>> The mf_write_subfield_value() call was also incorrect.
>> However, the 'match' variable is actually not used for
>> anything since checking removal in commit:
>>
>> dd43a558597b ("Do not perform validation in learn_parse();")
>>
>> So, just removing the call and the 'match' variable
>> entirely instead of fixing it.
>>
>> Fixes: 21b2fa617126 ("ofp-parse: Allow match field names in actions and
>> brackets in matches.")
>> Reported-at:
>> https://mail.openvswitch.org/pipermail/ovs-discuss/2022-November/052100.html
>> Reported-by: Thomas Lee <[email protected]>
>> Signed-off-by: Ilya Maximets <[email protected]>
>
> Reviewed-by: Simon Horman <[email protected]>
>
Thanks! Applied and backported down to 2.13.
Best regards, Ilya Maximets.
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