Commit 2aaf3fd5 authored Sep 24, 2021 by 王贇 Committed by Greg Kroah-Hartman Oct 17, 2021

net: prevent user from passing illegal stab size



[ Upstream commit b193e15ac69d56f35e1d8e2b5d16cbd47764d053 ]

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 log value passing from
user, and will use the insane value later to calculate pkt_len.

This patch just add a check on the size/cell_log to avoid insane
calculation.

Reported-by: Abaci <abaci@linux.alibaba.com>
Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 1e66a472

include/net/pkt_sched.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -11,6 +11,7 @@
		#include <uapi/linux/pkt_sched.h>

		#define DEFAULT_TX_QUEUE_LEN 1000
		#define STAB_SIZE_LOG_MAX 30

		struct qdisc_walker {
		int stop;

net/sched/sch_api.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -510,6 +510,12 @@ static struct qdisc_size_table qdisc_get_stab(struct nlattr opt,
		return stab;
		}

		if (s->size_log > STAB_SIZE_LOG_MAX \|\|
		s->cell_log > STAB_SIZE_LOG_MAX) {
		NL_SET_ERR_MSG(extack, "Invalid logarithmic size of size table");
		return ERR_PTR(-EINVAL);
		}

		stab = kmalloc(sizeof(stab) + tsize sizeof(u16), GFP_KERNEL);
		if (!stab)
		return ERR_PTR(-ENOMEM);