4.20-stable review patch. If anyone has any objections, please let me know. ------------------ From: Miaohe Lin <linmiaohe@xxxxxxxxxx> [ Upstream commit a843dc4ebaecd15fca1f4d35a97210f72ea1473b ] In func check_6rd,tunnel->ip6rd.relay_prefixlen may equal to 32,so UBSAN complain about it. UBSAN: Undefined behaviour in net/ipv6/sit.c:781:47 shift exponent 32 is too large for 32-bit type 'unsigned int' CPU: 6 PID: 20036 Comm: syz-executor.0 Not tainted 4.19.27 #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0xca/0x13e lib/dump_stack.c:113 ubsan_epilogue+0xe/0x81 lib/ubsan.c:159 __ubsan_handle_shift_out_of_bounds+0x293/0x2e8 lib/ubsan.c:425 check_6rd.constprop.9+0x433/0x4e0 net/ipv6/sit.c:781 try_6rd net/ipv6/sit.c:806 [inline] ipip6_tunnel_xmit net/ipv6/sit.c:866 [inline] sit_tunnel_xmit+0x141c/0x2720 net/ipv6/sit.c:1033 __netdev_start_xmit include/linux/netdevice.h:4300 [inline] netdev_start_xmit include/linux/netdevice.h:4309 [inline] xmit_one net/core/dev.c:3243 [inline] dev_hard_start_xmit+0x17c/0x780 net/core/dev.c:3259 __dev_queue_xmit+0x1656/0x2500 net/core/dev.c:3829 neigh_output include/net/neighbour.h:501 [inline] ip6_finish_output2+0xa36/0x2290 net/ipv6/ip6_output.c:120 ip6_finish_output+0x3e7/0xa20 net/ipv6/ip6_output.c:154 NF_HOOK_COND include/linux/netfilter.h:278 [inline] ip6_output+0x1e2/0x720 net/ipv6/ip6_output.c:171 dst_output include/net/dst.h:444 [inline] ip6_local_out+0x99/0x170 net/ipv6/output_core.c:176 ip6_send_skb+0x9d/0x2f0 net/ipv6/ip6_output.c:1697 ip6_push_pending_frames+0xc0/0x100 net/ipv6/ip6_output.c:1717 rawv6_push_pending_frames net/ipv6/raw.c:616 [inline] rawv6_sendmsg+0x2435/0x3530 net/ipv6/raw.c:946 inet_sendmsg+0xf8/0x5c0 net/ipv4/af_inet.c:798 sock_sendmsg_nosec net/socket.c:621 [inline] sock_sendmsg+0xc8/0x110 net/socket.c:631 ___sys_sendmsg+0x6cf/0x890 net/socket.c:2114 __sys_sendmsg+0xf0/0x1b0 net/socket.c:2152 do_syscall_64+0xc8/0x580 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Signed-off-by: linmiaohe <linmiaohe@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv6/sit.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -778,8 +778,9 @@ static bool check_6rd(struct ip_tunnel * pbw0 = tunnel->ip6rd.prefixlen >> 5; pbi0 = tunnel->ip6rd.prefixlen & 0x1f; - d = (ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >> - tunnel->ip6rd.relay_prefixlen; + d = tunnel->ip6rd.relay_prefixlen < 32 ? + (ntohl(v6dst->s6_addr32[pbw0]) << pbi0) >> + tunnel->ip6rd.relay_prefixlen : 0; pbi1 = pbi0 - tunnel->ip6rd.relay_prefixlen; if (pbi1 > 0)
