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

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Date:   Mon, 18 Sep 2023 13:49:38 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
Cc:     Kees Cook <keescook@...omium.org>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Jason Gunthorpe <jgg@...pe.ca>, 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 Fri, Sep 15, 2023 at 12:06:21PM -0600, Gustavo A. R. Silva wrote:
> 
> 
> 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.

You missed other places with similar arithmetic.
drivers/infiniband/core/device.c:       pdata_rcu = kzalloc(struct_size(pdata_rcu, pdata,
drivers/infiniband/core/device.c-                                       rdma_end_port(device) + 1),
drivers/infiniband/core/device.c-                           GFP_KERNEL);

drivers/infiniband/core/sa_query.c:     sa_dev = kzalloc(struct_size(sa_dev, port, e - s + 1), GFP_KERNEL);
drivers/infiniband/core/user_mad.c:     umad_dev = kzalloc(struct_size(umad_dev, ports, e - s + 1), GFP_KERNEL);

Thanks

> 
> > 
> > > 
> > > 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
> > > 
> >