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Date: Thu, 23 Sep 2021 17:08:13 +0800 From: 王贇 <yun.wang@...ux.alibaba.com> To: Jamal Hadi Salim <jhs@...atatu.com>, Cong Wang <xiyou.wangcong@...il.com>, Jiri Pirko <jiri@...nulli.us>, "David S. Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, "open list:TC subsystem" <netdev@...r.kernel.org>, open list <linux-kernel@...r.kernel.org> Subject: [PATCH] net: prevent user from passing illegal stab size We observed below report when playing with netlink sock: UBSAN: shift-out-of-bounds in net/sched/sch_api.c:580:10 shift exponent 249 is too large for 32-bit type CPU: 0 PID: 685 Comm: a.out Not tainted Call Trace: dump_stack_lvl+0x8d/0xcf ubsan_epilogue+0xa/0x4e __ubsan_handle_shift_out_of_bounds+0x161/0x182 __qdisc_calculate_pkt_len+0xf0/0x190 __dev_queue_xmit+0x2ed/0x15b0 it seems like kernel won't check the stab size_log passing from user, and will use the insane value later to calculate pkt_len. This patch just add a check on the size_log to avoid insane calculation. Reported-by: Abaci <abaci@...ux.alibaba.com> Signed-off-by: Michael Wang <yun.wang@...ux.alibaba.com> --- include/uapi/linux/pkt_sched.h | 1 + net/sched/sch_api.c | 3 +++ 2 files changed, 4 insertions(+) diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h index ec88590..fa194a0 100644 --- a/include/uapi/linux/pkt_sched.h +++ b/include/uapi/linux/pkt_sched.h @@ -98,6 +98,7 @@ struct tc_ratespec { }; #define TC_RTAB_SIZE 1024 +#define TC_LOG_MAX 30 struct tc_sizespec { unsigned char cell_log; diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c index 5e90e9b..1b6b8f8 100644 --- a/net/sched/sch_api.c +++ b/net/sched/sch_api.c @@ -513,6 +513,9 @@ static struct qdisc_size_table *qdisc_get_stab(struct nlattr *opt, return stab; } + if (s->size_log > TC_LOG_MAX) + return ERR_PTR(-EINVAL); + stab = kmalloc(sizeof(*stab) + tsize * sizeof(u16), GFP_KERNEL); if (!stab) return ERR_PTR(-ENOMEM); -- 1.8.3.1
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