[PATCH 5.4 79/86] net_sched: avoid shift-out-of-bounds in tcindex_set_parms()

Greg Kroah-Hartman
2021-01-26T09:12:04Z

From: Eric Dumazet <edumazet@google.com>

commit bcd0cf19ef8258ac31b9a20248b05c15a1f4b4b0 upstream.

tc_index being 16bit wide, we need to check that TCA_TCINDEX_SHIFT
attribute is not silly.

UBSAN: shift-out-of-bounds in net/sched/cls_tcindex.c:260:29
shift exponent 255 is too large for 32-bit type 'int'
CPU: 0 PID: 8516 Comm: syz-executor228 Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x107/0x163 lib/dump_stack.c:120
ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
__ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:395
valid_perfect_hash net/sched/cls_tcindex.c:260 [inline]
tcindex_set_parms.cold+0x1b/0x215 net/sched/cls_tcindex.c:425
tcindex_change+0x232/0x340 net/sched/cls_tcindex.c:546
tc_new_tfilter+0x13fb/0x21b0 net/sched/cls_api.c:2127
rtnetlink_rcv_msg+0x8b6/0xb80 net/core/rtnetlink.c:5555
netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2494
netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1330
netlink_sendmsg+0x907/0xe40 net/netlink/af_netlink.c:1919
sock_sendmsg_nosec net/socket.c:652 [inline]
sock_sendmsg+0xcf/0x120 net/socket.c:672
____sys_sendmsg+0x6e8/0x810 net/socket.c:2336
___sys_sendmsg+0xf3/0x170 net/socket.c:2390
__sys_sendmsg+0xe5/0x1b0 net/socket.c:2423
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Link: https://lore.kernel.org/r/20210114185229.1742255-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/sched/cls_tcindex.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/net/sched/cls_tcindex.c
+++ b/net/sched/cls_tcindex.c
@@ -366,9 +366,13 @@ tcindex_set_parms(struct net *net, struc
if (tb[TCA_TCINDEX_MASK])
cp->mask = nla_get_u16(tb[TCA_TCINDEX_MASK]);

- if (tb[TCA_TCINDEX_SHIFT])
+ if (tb[TCA_TCINDEX_SHIFT]) {
cp->shift = nla_get_u32(tb[TCA_TCINDEX_SHIFT]);
-
+ if (cp->shift > 16) {
+ err = -EINVAL;
+ goto errout;
+ }
+ }
if (!cp->hash) {
/* Hash not specified, use perfect hash if the upper limit
* of the hashing index is below the threshold.