From: M A Ramdhan ramdhan@starlabs.sg

stable inclusion from stable-v5.10.187 commit 80e0e8d5f54397c5048fa2274144134dd9dc91b5 category: bugfix bugzilla: 189032,https://gitee.com/src-openeuler/kernel/issues/I7N3N3 CVE: CVE-2023-3776

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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[ 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: Sasha Levin sashal@kernel.org Signed-off-by: Dong Chenchen dongchenchen2@huawei.com --- net/sched/cls_fw.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c index ec945294626a..41f0898a5a56 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; }