diff mbox series

[4.19] net/sched: cls_fw: Fix improper refcount update leads to use-after-free

Message ID 20230727174629.55740-1-sj@kernel.org
State New
Headers
Series [4.19] net/sched: cls_fw: Fix improper refcount update leads to use-after-free |

Commit Message

SeongJae Park July 27, 2023, 5:46 p.m. UTC 
  From: M A Ramdhan <ramdhan@starlabs.sg>

[ Upstream commit 0323bce598eea038714f941ce2b22541c46d488f ]

In the event of a failure in tcf_change_indev(), fw_set_parms() will
immediately return an error after incrementing or decrementing
reference counter in tcf_bind_filter().  If attacker can control
reference counter to zero and make reference freed, leading to
use after free.

In order to prevent this, move the point of possible failure above the
point where the TC_FW_CLASSID is handled.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: M A Ramdhan <ramdhan@starlabs.sg>
Signed-off-by: M A Ramdhan <ramdhan@starlabs.sg>
Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Reviewed-by: Pedro Tammela <pctammela@mojatatu.com>
Message-ID: <20230705161530.52003-1-ramdhan@starlabs.sg>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 net/sched/cls_fw.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

Comments

Greg KH Aug. 1, 2023, 8:21 a.m. UTC | #1 
On Thu, Jul 27, 2023 at 05:46:28PM +0000, SeongJae Park wrote:
> From: M A Ramdhan <ramdhan@starlabs.sg>
> 
> [ Upstream commit 0323bce598eea038714f941ce2b22541c46d488f ]
> 
> In the event of a failure in tcf_change_indev(), fw_set_parms() will
> immediately return an error after incrementing or decrementing
> reference counter in tcf_bind_filter().  If attacker can control
> reference counter to zero and make reference freed, leading to
> use after free.
> 
> In order to prevent this, move the point of possible failure above the
> point where the TC_FW_CLASSID is handled.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Reported-by: M A Ramdhan <ramdhan@starlabs.sg>
> Signed-off-by: M A Ramdhan <ramdhan@starlabs.sg>
> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
> Reviewed-by: Pedro Tammela <pctammela@mojatatu.com>
> Message-ID: <20230705161530.52003-1-ramdhan@starlabs.sg>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> Signed-off-by: SeongJae Park <sj@kernel.org>
> ---
>  net/sched/cls_fw.c | 10 +++++-----

Both now queued up, thanks.

greg k-h
diff mbox series

Patch

diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c
index cb2c62605fc76..5284a473c697f 100644
--- a/net/sched/cls_fw.c
+++ b/net/sched/cls_fw.c
@@ -221,11 +221,6 @@  static int fw_set_parms(struct net *net, struct tcf_proto *tp,
 	if (err < 0)
 		return err;
 
-	if (tb[TCA_FW_CLASSID]) {
-		f->res.classid = nla_get_u32(tb[TCA_FW_CLASSID]);
-		tcf_bind_filter(tp, &f->res, base);
-	}
-
 #ifdef CONFIG_NET_CLS_IND
 	if (tb[TCA_FW_INDEV]) {
 		int ret;
@@ -244,6 +239,11 @@  static int fw_set_parms(struct net *net, struct tcf_proto *tp,
 	} else if (head->mask != 0xFFFFFFFF)
 		return err;
 
+	if (tb[TCA_FW_CLASSID]) {
+		f->res.classid = nla_get_u32(tb[TCA_FW_CLASSID]);
+		tcf_bind_filter(tp, &f->res, base);
+	}
+
 	return 0;
 }