KASAN: global-out-of-bounds Read in inet_diag_bc

KASAN: global-out-of-bounds Read in inet_diag_bc_sk
Status: upstream: reported on 2020/05/02 08:59
Reported-by: syzbot+3f4c9f04a6740870299e@syzkaller.appspotmail.com
First crash: 31d, last: 30d

Sample crash report:

==================================================================
BUG: KASAN: global-out-of-bounds in cgroup_id include/linux/cgroup.h:312 [inline]
BUG: KASAN: global-out-of-bounds in inet_diag_bc_sk+0xb6e/0xc70 net/ipv4/inet_diag.c:749
Read of size 8 at addr ffffffff88e41590 by task syz-executor.0/14442

CPU: 1 PID: 14442 Comm: syz-executor.0 Not tainted 5.7.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0x5/0x315 mm/kasan/report.c:382
 __kasan_report.cold+0x35/0x4d mm/kasan/report.c:511
 kasan_report+0x33/0x50 mm/kasan/common.c:625
 cgroup_id include/linux/cgroup.h:312 [inline]
 inet_diag_bc_sk+0xb6e/0xc70 net/ipv4/inet_diag.c:749
 inet_diag_dump_icsk+0xbe4/0x1306 net/ipv4/inet_diag.c:1061
 __inet_diag_dump+0x8d/0x240 net/ipv4/inet_diag.c:1113
 netlink_dump+0x50b/0xf50 net/netlink/af_netlink.c:2245
 __netlink_dump_start+0x63f/0x910 net/netlink/af_netlink.c:2353
 netlink_dump_start include/linux/netlink.h:246 [inline]
 inet_diag_handler_cmd+0x263/0x2c0 net/ipv4/inet_diag.c:1278
 __sock_diag_cmd net/core/sock_diag.c:233 [inline]
 sock_diag_rcv_msg+0x2fe/0x3e0 net/core/sock_diag.c:264
 netlink_rcv_skb+0x15a/0x410 net/netlink/af_netlink.c:2469
 sock_diag_rcv+0x26/0x40 net/core/sock_diag.c:275
 netlink_unicast_kernel net/netlink/af_netlink.c:1303 [inline]
 netlink_unicast+0x537/0x740 net/netlink/af_netlink.c:1329
 netlink_sendmsg+0x882/0xe10 net/netlink/af_netlink.c:1918
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 sock_write_iter+0x289/0x3c0 net/socket.c:1004
 call_write_iter include/linux/fs.h:1907 [inline]
 do_iter_readv_writev+0x5a8/0x850 fs/read_write.c:694
 do_iter_write fs/read_write.c:999 [inline]
 do_iter_write+0x18b/0x600 fs/read_write.c:980
 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1072
 do_writev+0x27f/0x300 fs/read_write.c:1115
 do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x45c829
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f4b82418c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000050d140 RCX: 000000000045c829
RDX: 0000000000000004 RSI: 0000000020000200 RDI: 0000000000000007
RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000d18 R14: 00000000004cb1f4 R15: 00007f4b824196d4

The buggy address belongs to the variable:
 ip_vs_info_seq_ops+0x3f0/0xc00

Memory state around the buggy address:
 ffffffff88e41480: fa fa fa fa 00 07 fa fa fa fa fa fa 00 05 fa fa
 ffffffff88e41500: fa fa fa fa 00 00 03 fa fa fa fa fa 00 03 fa fa
>ffffffff88e41580: fa fa fa fa 00 04 fa fa fa fa fa fa 00 00 00 02
                         ^
 ffffffff88e41600: fa fa fa fa 00 07 fa fa fa fa fa fa 00 00 04 fa
 ffffffff88e41680: fa fa fa fa 00 05 fa fa fa fa fa fa 00 06 fa fa
==================================================================

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	Maintainers
ci-upstream-net-kasan-gce	2020/05/03 08:42	net-next	115506fe	5457883a	.config	log	report			andriin@fb.com, ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, davem@davemloft.net, john.fastabend@gmail.com, kafai@fb.com, kpsingh@chromium.org, kuba@kernel.org, kuznet@ms2.inr.ac.ru, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, songliubraving@fb.com, yhs@fb.com, yoshfuji@linux-ipv6.org
ci-upstream-net-kasan-gce	2020/05/02 07:53	net-next	4b4976a6	bc734e7a	.config	log	report			andriin@fb.com, ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net, davem@davemloft.net, john.fastabend@gmail.com, kafai@fb.com, kpsingh@chromium.org, kuba@kernel.org, kuznet@ms2.inr.ac.ru, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, songliubraving@fb.com, yhs@fb.com, yoshfuji@linux-ipv6.org