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* [PATCH][next] net_sched: Use struct_size() and flex_array_size() helpers
@ 2021-09-27 22:18 Gustavo A. R. Silva
  2021-09-28  0:56 ` Jakub Kicinski
  0 siblings, 1 reply; 2+ messages in thread
From: Gustavo A. R. Silva @ 2021-09-27 22:18 UTC (permalink / raw)
  To: Jamal Hadi Salim, Cong Wang, Jiri Pirko, David S. Miller, Jakub Kicinski
  Cc: netdev, linux-kernel, Gustavo A. R. Silva, linux-hardening

Make use of the struct_size() and flex_array_size() helpers instead of
an open-coded version, in order to avoid any potential type mistakes
or integer overflows that, in the worse scenario, could lead to heap
overflows.

Link: https://github.com/KSPP/linux/issues/160
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
---
 net/sched/sch_api.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 12f39a2dffd4..91820f67275c 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -507,7 +507,8 @@ static struct qdisc_size_table *qdisc_get_stab(struct nlattr *opt,
 	list_for_each_entry(stab, &qdisc_stab_list, list) {
 		if (memcmp(&stab->szopts, s, sizeof(*s)))
 			continue;
-		if (tsize > 0 && memcmp(stab->data, tab, tsize * sizeof(u16)))
+		if (tsize > 0 &&
+		    memcmp(stab->data, tab, flex_array_size(stab, data, tsize)))
 			continue;
 		stab->refcnt++;
 		return stab;
@@ -519,14 +520,14 @@ static struct qdisc_size_table *qdisc_get_stab(struct nlattr *opt,
 		return ERR_PTR(-EINVAL);
 	}
 
-	stab = kmalloc(sizeof(*stab) + tsize * sizeof(u16), GFP_KERNEL);
+	stab = kmalloc(struct_size(stab, data, tsize), GFP_KERNEL);
 	if (!stab)
 		return ERR_PTR(-ENOMEM);
 
 	stab->refcnt = 1;
 	stab->szopts = *s;
 	if (tsize > 0)
-		memcpy(stab->data, tab, tsize * sizeof(u16));
+		memcpy(stab->data, tab, flex_array_size(stab, data, tsize));
 
 	list_add_tail(&stab->list, &qdisc_stab_list);
 
-- 
2.27.0


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH][next] net_sched: Use struct_size() and flex_array_size() helpers
  2021-09-27 22:18 [PATCH][next] net_sched: Use struct_size() and flex_array_size() helpers Gustavo A. R. Silva
@ 2021-09-28  0:56 ` Jakub Kicinski
  0 siblings, 0 replies; 2+ messages in thread
From: Jakub Kicinski @ 2021-09-28  0:56 UTC (permalink / raw)
  To: Gustavo A. R. Silva
  Cc: Jamal Hadi Salim, Cong Wang, Jiri Pirko, David S. Miller, netdev,
	linux-kernel, linux-hardening

On Mon, 27 Sep 2021 17:18:49 -0500 Gustavo A. R. Silva wrote:
> Make use of the struct_size() and flex_array_size() helpers instead of
> an open-coded version, in order to avoid any potential type mistakes
> or integer overflows that, in the worse scenario, could lead to heap
> overflows.
> 
> Link: https://github.com/KSPP/linux/issues/160
> Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Does not apply to net-next, please rebase & resend. Thanks!

^ permalink raw reply	[flat|nested] 2+ messages in thread

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