linux-hardening - Re: [PATCH v2][next] RDMA/core: Use size_{add,mul}() in calls to struct

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Date:   Fri, 15 Sep 2023 12:06:21 -0600
From:   "Gustavo A. R. Silva" <gustavo@...eddedor.com>
To:     Kees Cook <keescook@...omium.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc:     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 v2][next] RDMA/core: Use size_{add,mul}() in calls to
 struct_size()



On 9/14/23 21:29, Kees Cook wrote:
> On Mon, Sep 11, 2023 at 05:27:59PM -0600, Gustavo A. R. Silva wrote:
>> Harden calls to struct_size() with size_add() and size_mul().
> 
> Specifically, make sure that open-coded arithmetic cannot cause an
> overflow/wraparound. (i.e. it will stay saturated at SIZE_MAX.)

Yep; I have another patch where I explain this in similar terms.

I'll send it, shortly.

> 
>>
>> Fixes: 467f432a521a ("RDMA/core: Split port and device counter sysfs attributes")
>> Fixes: a4676388e2e2 ("RDMA/core: Simplify how the gid_attrs sysfs is created")
>> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
> 
> Reviewed-by: Kees Cook <keescook@...omium.org>

Thanks!

--
Gustavo

> 
> -Kees
> 
>> ---
>> Changes in v2:
>>   - Update changelog text: remove the part about binary differences (it
>>     was added by mistake).
>>
>>   drivers/infiniband/core/sysfs.c | 10 +++++-----
>>   1 file changed, 5 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/infiniband/core/sysfs.c b/drivers/infiniband/core/sysfs.c
>> index ee59d7391568..ec5efdc16660 100644
>> --- a/drivers/infiniband/core/sysfs.c
>> +++ b/drivers/infiniband/core/sysfs.c
>> @@ -903,7 +903,7 @@ alloc_hw_stats_device(struct ib_device *ibdev)
>>   	 * Two extra attribue elements here, one for the lifespan entry and
>>   	 * one to NULL terminate the list for the sysfs core code
>>   	 */
>> -	data = kzalloc(struct_size(data, attrs, stats->num_counters + 1),
>> +	data = kzalloc(struct_size(data, attrs, size_add(stats->num_counters, 1)),
>>   		       GFP_KERNEL);
>>   	if (!data)
>>   		goto err_free_stats;
>> @@ -1009,7 +1009,7 @@ alloc_hw_stats_port(struct ib_port *port, struct attribute_group *group)
>>   	 * Two extra attribue elements here, one for the lifespan entry and
>>   	 * one to NULL terminate the list for the sysfs core code
>>   	 */
>> -	data = kzalloc(struct_size(data, attrs, stats->num_counters + 1),
>> +	data = kzalloc(struct_size(data, attrs, size_add(stats->num_counters, 1)),
>>   		       GFP_KERNEL);
>>   	if (!data)
>>   		goto err_free_stats;
>> @@ -1140,7 +1140,7 @@ static int setup_gid_attrs(struct ib_port *port,
>>   	int ret;
>>   
>>   	gid_attr_group = kzalloc(struct_size(gid_attr_group, attrs_list,
>> -					     attr->gid_tbl_len * 2),
>> +					     size_mul(attr->gid_tbl_len, 2)),
>>   				 GFP_KERNEL);
>>   	if (!gid_attr_group)
>>   		return -ENOMEM;
>> @@ -1205,8 +1205,8 @@ static struct ib_port *setup_port(struct ib_core_device *coredev, int port_num,
>>   	int ret;
>>   
>>   	p = kvzalloc(struct_size(p, attrs_list,
>> -				attr->gid_tbl_len + attr->pkey_tbl_len),
>> -		    GFP_KERNEL);
>> +				size_add(attr->gid_tbl_len, attr->pkey_tbl_len)),
>> +		     GFP_KERNEL);
>>   	if (!p)
>>   		return ERR_PTR(-ENOMEM);
>>   	p->ibdev = device;
>> -- 
>> 2.34.1
>>
>