UBSAN: shift-out-of-bounds in netlink

UBSAN: shift-out-of-bounds in netlink_recvmsg
Status: upstream: reported C repro on 2021/02/18 17:21
Reported-by: syzbot+cdb35bcbfac5f493e2af@syzkaller.appspotmail.com
First crash: 11d, last: 11d

Cause bisection: introduced by (bisect log) :
commit b911c97c7dc771633c68ea9b8f15070f8af3d323
Author: Florian Westphal <fw@strlen.de>
Date: Sat Feb 13 00:00:01 2021 +0000

mptcp: add netlink event support

Crash: UBSAN: shift-out-of-bounds in netlink_recvmsg (log)
Repro: C syz .config

Sample crash report:

================================================================================
UBSAN: shift-out-of-bounds in net/netlink/af_netlink.c:160:19
shift exponent 32 is too large for 32-bit type 'int'
CPU: 1 PID: 8437 Comm: syz-executor324 Not tainted 5.11.0-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: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
 netlink_group_mask net/netlink/af_netlink.c:160 [inline]
 netlink_group_mask net/netlink/af_netlink.c:158 [inline]
 netlink_recvmsg.cold+0x1a/0x1f net/netlink/af_netlink.c:1992
 sock_recvmsg_nosec net/socket.c:886 [inline]
 sock_recvmsg net/socket.c:904 [inline]
 sock_recvmsg net/socket.c:900 [inline]
 ____sys_recvmsg+0x2c4/0x600 net/socket.c:2571
 ___sys_recvmsg+0x127/0x200 net/socket.c:2613
 __sys_recvmsg+0xe2/0x1a0 net/socket.c:2649
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x444bf9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 81 14 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f68a1130318 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 00000000004ca408 RCX: 0000000000444bf9
RDX: 0000000000000002 RSI: 0000000020000440 RDI: 0000000000000003
RBP: 00000000004ca400 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 8001000a373e1537
R13: 00007ffc4d11dcaf R14: 00007f68a1130400 R15: 0000000000022000
================================================================================

Crashes (3):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci-upstream-net-kasan-gce	2021/02/17 21:29	net-next	b646acd5	14052202	.config	log	report	syz	C		UBSAN: shift-out-of-bounds in netlink_recvmsg
ci-upstream-bpf-next-kasan-gce	2021/02/17 21:03	bpf-next	b646acd5	14052202	.config	log	report	syz	C		UBSAN: shift-out-of-bounds in netlink_recvmsg
ci-upstream-bpf-next-kasan-gce	2021/02/17 20:35	bpf-next	b646acd5	14052202	.config	log	report			info	UBSAN: shift-out-of-bounds in netlink_recvmsg