Subject: [syzbot] UBSAN: shift-out-of-bounds in xfrm_set_default

From: syzbot <[email-masked]>
Date: Tue, 27 Jul 2021 05:47:21 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    90d856e71443 Add linux-next specific files for 20210723
git tree:       linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=133fd00a300000
kernel config:  https://syzkaller.appspot.com/x/.config?x=298516715f6ad5cd
dashboard link: https://syzkaller.appspot.com/bug?extid=9cd5837a045bbee5b810
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=1263bba6300000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1066b4d4300000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

netlink: 228 bytes leftover after parsing attributes in process `syz-executor669'.
================================================================================
UBSAN: shift-out-of-bounds in net/xfrm/xfrm_user.c:1969:18
shift exponent 255 is too large for 32-bit type 'int'
CPU: 0 PID: 8437 Comm: syz-executor669 Not tainted 5.14.0-rc2-next-20210723-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_set_default.cold+0x21/0x102 net/xfrm/xfrm_user.c:1969
 xfrm_user_rcv_msg+0x430/0xa20 net/xfrm/xfrm_user.c:2864
 netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504
 xfrm_netlink_rcv+0x6b/0x90 net/xfrm/xfrm_user.c:2886
 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:703 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:723
 ____sys_sendmsg+0x6e8/0x810 net/socket.c:2392
 ___sys_sendmsg+0xf3/0x170 net/socket.c:2446
 __sys_sendmsg+0xe5/0x1b0 net/socket.c:2475
 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: 0033:0x43f0d9
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:00007ffc71f859f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000400488 RCX: 000000000043f0d9
RDX: 0000000000000000 RSI: 0000000020000740 RDI: 0000000000000003
RBP: 00000000004030c0 R08: 0000000000000000 R09: 0000000000400488
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000403150
R13: 0000000000000000 R14: 00000000004ad018 R15: 0000000000400488
================================================================================

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