Re: [PATCH] IB/rdmavt: Fix target union member for rvt_post_one_wr()

[Dennis Dalessandro]

On 2/21/23 8:00 AM, Dennis Dalessandro wrote:
> On 2/18/23 1:57 PM, Kees Cook wrote:
>> The "cplen" result used by the memcpy() into struct rvt_swqe "wqe" may
>> be sized to 80 for struct rvt_ud_wr (which is member "ud_wr", not "wr"
>> which is only 40 bytes in size). Change the destination union member so
>> the compiler can use the correct bounds check.
>>
>> struct rvt_swqe {
>>         union {
>>                 struct ib_send_wr wr;   /* don't use wr.sg_list */
>>                 struct rvt_ud_wr ud_wr;
>> 		...
>> 	};
>> 	...
>> };
>>
>> Silences false positive memcpy() run-time warning:
>>
>>   memcpy: detected field-spanning write (size 80) of single field "&wqe->wr" at drivers/infiniband/sw/rdmavt/qp.c:2043 (size 40)
>>
>> Reported-by: Zhang Yi <yizhan@xxxxxxxxxx>
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=216561
>> Cc: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxxxxxxxxxxxxx>
>> Cc: Jason Gunthorpe <jgg@xxxxxxxx>
>> Cc: Leon Romanovsky <leon@xxxxxxxxxx>
>> Cc: linux-rdma@xxxxxxxxxxxxxxx
>> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
>> ---
>>  drivers/infiniband/sw/rdmavt/qp.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/infiniband/sw/rdmavt/qp.c b/drivers/infiniband/sw/rdmavt/qp.c
>> index 3acab569fbb9..3f707e1fa517 100644
>> --- a/drivers/infiniband/sw/rdmavt/qp.c
>> +++ b/drivers/infiniband/sw/rdmavt/qp.c
>> @@ -2040,7 +2040,7 @@ static int rvt_post_one_wr(struct rvt_qp *qp,
>>  	wqe = rvt_get_swqe_ptr(qp, qp->s_head);
>>  
>>  	/* cplen has length from above */
>> -	memcpy(&wqe->wr, wr, cplen);
>> +	memcpy(&wqe->ud_wr, wr, cplen);
>>  
>>  	wqe->length = 0;
>>  	j = 0;
> 
> Thanks for the patch. We've been debating this issue internally since last week.
> The problem I have is this makes it look like everything is a "UD" req when it
> could be a different QP type. Maybe we just need a comment explaining.

For what it's worth I did test this patch. If you could add the comment that'd
be great. If not I can touch it up later.

Reviewed-by: Dennis Dalessandro <dennis.dalessandro@xxxxxxxxxxxxxxxxxxxx>