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

[Gustavo A. R. Silva]

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 <gustavo...@kernel.org>

Reviewed-by: Kees Cook <keesc...@chromium.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