From: Lee Jones <lee@kernel.org> mainline inclusion from mainline-v6.4-rc7 commit 04c55383fa5689357bcdd2c8036725a55ed632bc category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I7N3N2 CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- In the event of a failure in tcf_change_indev(), u32_set_parms() will immediately return without decrementing the recently incremented reference counter. If this happens enough times, the counter will rollover and the reference freed, leading to a double free which can be used to do 'bad things'. In order to prevent this, move the point of possible failure above the point where the reference counter is incremented. Also save any meaningful return values to be applied to the return data at the appropriate point in time. This issue was caught with KASAN. Fixes: 705c7091262d ("net: sched: cls_u32: no need to call tcf_exts_change for newly allocated struct") Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Lee Jones <lee@kernel.org> Reviewed-by: Eric Dumazet <edumazet@google.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Signed-off-by: David S. Miller <davem@davemloft.net> conflict: net/sched/cls_u32.c Signed-off-by: Lu Wei <luwei32@huawei.com> --- net/sched/cls_u32.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/net/sched/cls_u32.c b/net/sched/cls_u32.c index 23d95db99121..45807e125401 100644 --- a/net/sched/cls_u32.c +++ b/net/sched/cls_u32.c @@ -777,12 +777,20 @@ static int u32_set_parms(struct net *net, struct tcf_proto *tp, struct nlattr *est, bool ovr, struct netlink_ext_ack *extack) { - int err; + int err, ifindex = -1; err = tcf_exts_validate(net, tp, tb, est, &n->exts, ovr, extack); if (err < 0) return err; +#ifdef CONFIG_NET_CLS_IND + if (tb[TCA_U32_INDEV]) { + ifindex = tcf_change_indev(net, tb[TCA_U32_INDEV], extack); + if (ifindex < 0) + return -EINVAL; + } +#endif + if (tb[TCA_U32_LINK]) { u32 handle = nla_get_u32(tb[TCA_U32_LINK]); struct tc_u_hnode *ht_down = NULL, *ht_old; @@ -814,13 +822,8 @@ static int u32_set_parms(struct net *net, struct tcf_proto *tp, } #ifdef CONFIG_NET_CLS_IND - if (tb[TCA_U32_INDEV]) { - int ret; - ret = tcf_change_indev(net, tb[TCA_U32_INDEV], extack); - if (ret < 0) - return -EINVAL; - n->ifindex = ret; - } + if (ifindex >= 0) + n->ifindex = ifindex; #endif return 0; } -- 2.34.1