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SubjectKASAN: global-out-of-bounds Read in inet_diag_bc_sk
From
Hello,

syzbot found the following crash on:

HEAD commit: 4b4976a6 Merge branch 'net-ReST-part-three'
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=13e3824c100000
kernel config: https://syzkaller.appspot.com/x/.config?x=b1494ce3fbc02154
dashboard link: https://syzkaller.appspot.com/bug?extid=3f4c9f04a6740870299e
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+3f4c9f04a6740870299e@syzkaller.appspotmail.com

==================================================================
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 ffffffff8d22eed0 by task syz-executor.2/16922

CPU: 1 PID: 16922 Comm: syz-executor.2 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:00007f6839177c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000050d140 RCX: 000000000045c829
RDX: 0000000000000001 RSI: 00000000200000c0 RDI: 0000000000000007
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000d18 R14: 00000000004cb1f4 R15: 00007f68391786d4

The buggy address belongs to the variable:
__key.82892+0x30/0x40

Memory state around the buggy address:
ffffffff8d22ed80: fa fa fa fa 00 00 fa fa fa fa fa fa 00 00 fa fa
ffffffff8d22ee00: fa fa fa fa 00 fa fa fa fa fa fa fa 00 00 fa fa
>ffffffff8d22ee80: fa fa fa fa 00 00 fa fa fa fa fa fa 00 00 fa fa
^
ffffffff8d22ef00: fa fa fa fa 00 00 fa fa fa fa fa fa 00 00 fa fa
ffffffff8d22ef80: fa fa fa fa 00 00 fa fa fa fa fa fa 00 00 fa fa
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

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