Date:   Mon, 20 Dec 2021 08:33:25 -0800
From:   syzbot <syzbot+cdbd40e0c3ca02cae3b7@...kaller.appspotmail.com>
To:     andrii@...nel.org, ast@...nel.org, bpf@...r.kernel.org,
        daniel@...earbox.net, davem@...emloft.net, glider@...gle.com,
        john.fastabend@...il.com, kafai@...com, kpsingh@...nel.org,
        kuba@...nel.org, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, songliubraving@...com,
        syzkaller-bugs@...glegroups.com, yhs@...com
Subject: [syzbot] KMSAN: kernel-infoleak in move_addr_to_user (6)

Hello,

syzbot found the following issue on:

HEAD commit:    b0a8b5053e8b kmsan: core: add dependency on DEBUG_KERNEL
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=14a45071b00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=46a956fc7a887c60
dashboard link: https://syzkaller.appspot.com/bug?extid=cdbd40e0c3ca02cae3b7
compiler:       clang version 14.0.0 (/usr/local/google/src/llvm-git-monorepo 2b554920f11c8b763cd9ed9003f4e19b919b8e1f), GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1343f443b00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16efa493b00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+cdbd40e0c3ca02cae3b7@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:121 [inline]
BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:121 [inline] lib/usercopy.c:33
BUG: KMSAN: kernel-infoleak in _copy_to_user+0x1c9/0x270 lib/usercopy.c:33 lib/usercopy.c:33
 instrument_copy_to_user include/linux/instrumented.h:121 [inline]
 instrument_copy_to_user include/linux/instrumented.h:121 [inline] lib/usercopy.c:33
 _copy_to_user+0x1c9/0x270 lib/usercopy.c:33 lib/usercopy.c:33
 copy_to_user include/linux/uaccess.h:209 [inline]
 copy_to_user include/linux/uaccess.h:209 [inline] net/socket.c:287
 move_addr_to_user+0x3f6/0x600 net/socket.c:287 net/socket.c:287
 __sys_getpeername+0x470/0x6b0 net/socket.c:1987 net/socket.c:1987
 __do_sys_getpeername net/socket.c:1997 [inline]
 __se_sys_getpeername net/socket.c:1994 [inline]
 __do_sys_getpeername net/socket.c:1997 [inline] net/socket.c:1994
 __se_sys_getpeername net/socket.c:1994 [inline] net/socket.c:1994
 __x64_sys_getpeername+0xda/0x120 net/socket.c:1994 net/socket.c:1994
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_x64 arch/x86/entry/common.c:51 [inline] arch/x86/entry/common.c:82
 do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Uninit was stored to memory at:
 tipc_getname+0x575/0x5e0 net/tipc/socket.c:757 net/tipc/socket.c:757
 __sys_getpeername+0x3b3/0x6b0 net/socket.c:1984 net/socket.c:1984
 __do_sys_getpeername net/socket.c:1997 [inline]
 __se_sys_getpeername net/socket.c:1994 [inline]
 __do_sys_getpeername net/socket.c:1997 [inline] net/socket.c:1994
 __se_sys_getpeername net/socket.c:1994 [inline] net/socket.c:1994
 __x64_sys_getpeername+0xda/0x120 net/socket.c:1994 net/socket.c:1994
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_x64 arch/x86/entry/common.c:51 [inline] arch/x86/entry/common.c:82
 do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Uninit was stored to memory at:
 msg_set_word net/tipc/msg.h:212 [inline]
 msg_set_destport net/tipc/msg.h:619 [inline]
 msg_set_word net/tipc/msg.h:212 [inline] net/tipc/socket.c:1486
 msg_set_destport net/tipc/msg.h:619 [inline] net/tipc/socket.c:1486
 __tipc_sendmsg+0x44fa/0x5890 net/tipc/socket.c:1486 net/tipc/socket.c:1486
 tipc_sendmsg+0xeb/0x140 net/tipc/socket.c:1402 net/tipc/socket.c:1402
 sock_sendmsg_nosec net/socket.c:704 [inline]
 sock_sendmsg net/socket.c:724 [inline]
 sock_sendmsg_nosec net/socket.c:704 [inline] net/socket.c:2409
 sock_sendmsg net/socket.c:724 [inline] net/socket.c:2409
 ____sys_sendmsg+0xe11/0x12c0 net/socket.c:2409 net/socket.c:2409
 ___sys_sendmsg net/socket.c:2463 [inline]
 ___sys_sendmsg net/socket.c:2463 [inline] net/socket.c:2492
 __sys_sendmsg+0x704/0x840 net/socket.c:2492 net/socket.c:2492
 __do_sys_sendmsg net/socket.c:2501 [inline]
 __se_sys_sendmsg net/socket.c:2499 [inline]
 __do_sys_sendmsg net/socket.c:2501 [inline] net/socket.c:2499
 __se_sys_sendmsg net/socket.c:2499 [inline] net/socket.c:2499
 __x64_sys_sendmsg+0xe2/0x120 net/socket.c:2499 net/socket.c:2499
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_x64 arch/x86/entry/common.c:51 [inline] arch/x86/entry/common.c:82
 do_syscall_64+0x54/0xd0 arch/x86/entry/common.c:82 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Local variable skaddr created at:
 __tipc_sendmsg+0x2d0/0x5890 net/tipc/socket.c:1419 net/tipc/socket.c:1419
 tipc_sendmsg+0xeb/0x140 net/tipc/socket.c:1402 net/tipc/socket.c:1402

Bytes 4-7 of 16 are uninitialized
Memory access of size 16 starts at ffff888113753e00
Data copied to user address 0000000020000280

CPU: 1 PID: 3479 Comm: syz-executor115 Not tainted 5.16.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
=====================================================


---
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