This is a note to let you know that I've just added the patch titled
net/sched: cls_fw: Fix improper refcount update leads to use-after-free
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-sched-cls_fw-fix-improper-refcount-update-leads-.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 5cd2235cbcfe698a051c0c291ee3571932772730
Author: M A Ramdhan <ramdhan@xxxxxxxxxxx>
Date: Wed Jul 5 12:15:30 2023 -0400
net/sched: cls_fw: Fix improper refcount update leads to use-after-free
[ 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@xxxxxxxxxxx>
Signed-off-by: M A Ramdhan <ramdhan@xxxxxxxxxxx>
Acked-by: Jamal Hadi Salim <jhs@xxxxxxxxxxxx>
Reviewed-by: Pedro Tammela <pctammela@xxxxxxxxxxxx>
Message-ID: <20230705161530.52003-1-ramdhan@xxxxxxxxxxx>
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c
index 8654b0ce997c1..ea52c320f67c4 100644
--- a/net/sched/cls_fw.c
+++ b/net/sched/cls_fw.c
@@ -210,11 +210,6 @@ 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);
@@ -231,6 +226,11 @@ 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;
}
