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

["Gustavo A. R. Silva" <gustavo@xxxxxxxxxxxxxx>]

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@xxxxxxxxxx>
>
> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>

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