Re: [syzbot] UBSAN: shift-out-of-bounds in netlink_recvmsg

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
UBSAN: shift-out-of-bounds in netlink_recvmsg

================================================================================
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: 10158 Comm: syz-executor.2 Not tainted 5.11.0-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+0xfa/0x151 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+0x44/0xae
RIP: 0033:0x465d99
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f2d6bf4c188 EFLAGS: 00000246 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 0000000000465d99
RDX: 0000000000000002 RSI: 0000000020000440 RDI: 0000000000000003
RBP: 00000000004bcf27 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60
R13: 00007ffd739767cf R14: 00007f2d6bf4c300 R15: 0000000000022000
================================================================================


Tested on:

commit: d310ec03 Merge tag 'perf-core-2021-02-17' of git://git.ker..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=1713d656d00000
kernel config: https://syzkaller.appspot.com/x/.config?x=4be65db84843110a
dashboard link: https://syzkaller.appspot.com/bug?extid=cdb35bcbfac5f493e2af
compiler: