linux-kernel - Re: [PATCH] IB/rdmavt: Fix target union member for rvt_post_one

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Message-ID: <81922cc5-4de3-bcd6-b0c3-8f9e61a1e7c5@cornelisnetworks.com>
Date:   Tue, 28 Feb 2023 10:37:17 -0500
From:   Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>
To:     Kees Cook <keescook@...omium.org>
Cc:     Zhang Yi <yizhan@...hat.com>, Jason Gunthorpe <jgg@...pe.ca>,
        Leon Romanovsky <leon@...nel.org>, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: Re: [PATCH] IB/rdmavt: Fix target union member for rvt_post_one_wr()



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@...hat.com>
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=216561
>> Cc: Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>
>> Cc: Jason Gunthorpe <jgg@...pe.ca>
>> Cc: Leon Romanovsky <leon@...nel.org>
>> Cc: linux-rdma@...r.kernel.org
>> Signed-off-by: Kees Cook <keescook@...omium.org>
>> ---
>>  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@...nelisnetworks.com>