linux-kernel - [syzbot] KMSAN: kernel-infoleak in vmci_host_unlocked

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Message-ID: <000000000000cadfcb05e9c2d04b@google.com>
Date:   Wed, 28 Sep 2022 13:43:39 -0700
From:   syzbot <syzbot+39be4da489ed2493ba25@...kaller.appspotmail.com>
To:     arnd@...db.de, bryantan@...are.com, glider@...gle.com,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        pv-drivers@...are.com, rjalisatgi@...are.com,
        syzkaller-bugs@...glegroups.com, vdasa@...are.com
Subject: [syzbot] KMSAN: kernel-infoleak in vmci_host_unlocked_ioctl (2)

Hello,

syzbot found the following issue on:

HEAD commit:    466a27efa4f0 x86: kmsan: handle CPU entry area
git tree:       https://github.com/google/kmsan.git master
console+strace: https://syzkaller.appspot.com/x/log.txt?x=144595ef080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=121c7ef28ec597bd
dashboard link: https://syzkaller.appspot.com/bug?extid=39be4da489ed2493ba25
compiler:       clang version 15.0.0 (https://github.com/llvm/llvm-project.git 610139d2d9ce6746b3c617fb3e2f7886272d26ff), GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10afe26c880000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=108e0950880000

Downloadable assets:
disk image: https://storage.googleapis.com/757beb3f2001/disk-466a27ef.raw.xz
vmlinux: https://storage.googleapis.com/1219d90ba613/vmlinux-466a27ef.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+39be4da489ed2493ba25@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:121 [inline]
BUG: KMSAN: kernel-infoleak in _copy_to_user+0xbc/0x100 lib/usercopy.c:33
 instrument_copy_to_user include/linux/instrumented.h:121 [inline]
 _copy_to_user+0xbc/0x100 lib/usercopy.c:33
 copy_to_user include/linux/uaccess.h:169 [inline]
 vmci_host_do_receive_datagram drivers/misc/vmw_vmci/vmci_host.c:431 [inline]
 vmci_host_unlocked_ioctl+0x1cd3/0x5480 drivers/misc/vmw_vmci/vmci_host.c:925
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0x222/0x400 fs/ioctl.c:856
 __x64_sys_ioctl+0x92/0xd0 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Uninit was stored to memory at:
 kmemdup+0x89/0xd0 mm/util.c:131
 dg_dispatch_as_host drivers/misc/vmw_vmci/vmci_datagram.c:271 [inline]
 vmci_datagram_dispatch+0x4ee/0x13f0 drivers/misc/vmw_vmci/vmci_datagram.c:339
 qp_notify_peer+0x1fe/0x310 drivers/misc/vmw_vmci/vmci_queue_pair.c:1479
 qp_broker_attach drivers/misc/vmw_vmci/vmci_queue_pair.c:1662 [inline]
 qp_broker_alloc+0x3370/0x3850 drivers/misc/vmw_vmci/vmci_queue_pair.c:1750
 vmci_qp_broker_alloc+0xdf/0x120 drivers/misc/vmw_vmci/vmci_queue_pair.c:1940
 vmci_host_do_alloc_queuepair drivers/misc/vmw_vmci/vmci_host.c:488 [inline]
 vmci_host_unlocked_ioctl+0x3305/0x5480 drivers/misc/vmw_vmci/vmci_host.c:927
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0x222/0x400 fs/ioctl.c:856
 __x64_sys_ioctl+0x92/0xd0 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Local variable ev created at:
 qp_notify_peer+0x5a/0x310 drivers/misc/vmw_vmci/vmci_queue_pair.c:1456
 qp_broker_attach drivers/misc/vmw_vmci/vmci_queue_pair.c:1662 [inline]
 qp_broker_alloc+0x3370/0x3850 drivers/misc/vmw_vmci/vmci_queue_pair.c:1750

Bytes 28-31 of 48 are uninitialized
Memory access of size 48 starts at ffff88811768de80
Data copied to user address 0000000020000100

CPU: 0 PID: 3489 Comm: syz-executor851 Not tainted 6.0.0-rc5-syzkaller-48540-g466a27efa4f0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
=====================================================


---
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