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[SRU,Focal/Jammy/OEM-5.17/Kinetic/OEM-6.0/Lunar] net/sched: cls_fw: Fix improper refcount update leads to use-after-free

Message ID 20230728065738.1057030-2-cengiz.can@canonical.com
State New
Headers show
Series [SRU,Focal/Jammy/OEM-5.17/Kinetic/OEM-6.0/Lunar] net/sched: cls_fw: Fix improper refcount update leads to use-after-free | expand

Commit Message

Cengiz Can July 28, 2023, 6:57 a.m. UTC 
From: M A Ramdhan <ramdhan@starlabs.sg>

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>
CVE-2023-3776
(cherry picked from commit 0323bce598eea038714f941ce2b22541c46d488f)
Signed-off-by: Cengiz Can <cengiz.can@canonical.com>
---
 net/sched/cls_fw.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c
index ae9439a6c56c..8641f8059317 100644
--- a/net/sched/cls_fw.c
+++ b/net/sched/cls_fw.c
@@ -212,11 +212,6 @@  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);
-	}
-
 	if (tb[TCA_FW_INDEV]) {
 		int ret;
 		ret = tcf_change_indev(net, tb[TCA_FW_INDEV], extack);
@@ -233,6 +228,11 @@  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;
 }