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net: prevent user from passing illegal stab size

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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>
This commit is contained in:
王贇 2021-09-24 10:35:58 +08:00 committed by David S. Miller
parent 7fe7f3182a
commit b193e15ac6
2 changed files with 7 additions and 0 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
include/net/pkt_sched.h
View file

@ -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;

6
net/sched/sch_api.c
View file

@ -513,6 +513,12 @@ 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);