[syzbot] UBSAN: shift-out-of-bounds in xfrm_get_default

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    eaf2aaec0be4 Merge tag 'wireless-drivers-next-2021-08-29' ..
git tree:       net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=1219326d300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d2f9d4c9ff8c5ae7
dashboard link: https://syzkaller.appspot.com/bug?extid=b2be9dd8ca6f6c73ee2d
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11e6e3a9300000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10de8a6d300000

The issue was bisected to:

commit 2d151d39073aff498358543801fca0f670fea981
Author: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Date:   Sun Jul 18 07:11:06 2021 +0000

    xfrm: Add possibility to set the default to block if we have no policy

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=114523fe300000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=134523fe300000
console output: https://syzkaller.appspot.com/x/log.txt?x=154523fe300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b2be9dd8ca6f6c73ee2d@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 2d151d39073a ("xfrm: Add possibility to set the default to block if we have no policy")

netlink: 172 bytes leftover after parsing attributes in process `syz-executor354'.
================================================================================
UBSAN: shift-out-of-bounds in net/xfrm/xfrm_user.c:2010:49
shift exponent 224 is too large for 32-bit type 'int'
CPU: 1 PID: 8447 Comm: syz-executor354 Not tainted 5.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105
 ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
 __ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:327
 xfrm_get_default.cold+0x1f/0x75 net/xfrm/xfrm_user.c:2010
 xfrm_user_rcv_msg+0x430/0xa20 net/xfrm/xfrm_user.c:2869
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
 xfrm_netlink_rcv+0x6b/0x90 net/xfrm/xfrm_user.c:2891
 netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]
 netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340
 netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:724
 sock_no_sendpage+0xf3/0x130 net/core/sock.c:2980
 kernel_sendpage.part.0+0x1a0/0x340 net/socket.c:3496
 kernel_sendpage net/socket.c:3493 [inline]
 sock_sendpage+0xe5/0x140 net/socket.c:1003
 pipe_to_sendpage+0x2ad/0x380 fs/splice.c:364
 splice_from_pipe_feed fs/splice.c:418 [inline]
 __splice_from_pipe+0x43e/0x8a0 fs/splice.c:562
 splice_from_pipe fs/splice.c:597 [inline]
 generic_splice_sendpage+0xd4/0x140 fs/splice.c:746
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x110/0x180 fs/splice.c:936
 splice_direct_to_actor+0x34b/0x8c0 fs/splice.c:891
 do_splice_direct+0x1b3/0x280 fs/splice.c:979
 do_sendfile+0x9f0/0x1120 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0x1cc/0x210 fs/read_write.c:1311
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x43f019
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd24165888 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043f019
RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000005
RBP: 0000000000403000 R08: 0000000000400488 R09: 0000000000400488
R10: 0000000100000002 R11: 0000000000000246 R12: 0000000000403090
R13: 0000000000000000 R14: 00000000004ac018 R15: 0000000000400488
================================================================================


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