[syzbot] KMSAN: kernel-infoleak in move_addr_to_user (6)

[syzbot]

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+cdbd40...@syzkaller.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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[Pavel Skripkin]

On 12/20/21 19:33, syzbot wrote:
> 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+cdbd40...@syzkaller.appspotmail.com
>

Looks like missing memset(0). tipc_nametbl_lookup_anycast() may return
before initializing sk.ref

> * On exit:
> *
> * - If lookup is deferred to another node, leave 'sk->node' unchanged and
> * return 'true'.

And then sk.ref is passed to msg_set_destport().

There is also one more place with similar possible uninit-value in
tipc_msg_lookup_dest().



With regards,
Pavel Skripkin