linux-kernel - [syzbot] [serial?] KMSAN: kernel-infoleak in con_font

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Message-ID: <000000000000e4fa7f0617e76674@google.com>
Date: Tue, 07 May 2024 18:41:31 -0700
From: syzbot <syzbot+8d57540d08e2510c9741@...kaller.appspotmail.com>
To: gregkh@...uxfoundation.org, jirislaby@...nel.org, 
	linux-kernel@...r.kernel.org, linux-serial@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: [syzbot] [serial?] KMSAN: kernel-infoleak in con_font_op

Hello,

syzbot found the following issue on:

HEAD commit:    3d25a941ea50 Merge tag 'block-6.9-20240503' of git://git.k..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1503a62f180000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bbf567496022057b
dashboard link: https://syzkaller.appspot.com/bug?extid=8d57540d08e2510c9741
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/31394def760d/disk-3d25a941.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b07167755ad1/vmlinux-3d25a941.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7cb810157366/bzImage-3d25a941.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8d57540d08e2510c9741@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: kernel-infoleak in instrument_copy_to_user include/linux/instrumented.h:114 [inline]
BUG: KMSAN: kernel-infoleak in _copy_to_user+0xbc/0x110 lib/usercopy.c:40
 instrument_copy_to_user include/linux/instrumented.h:114 [inline]
 _copy_to_user+0xbc/0x110 lib/usercopy.c:40
 copy_to_user include/linux/uaccess.h:191 [inline]
 con_font_get drivers/tty/vt/vt.c:4750 [inline]
 con_font_op+0x14a2/0x1710 drivers/tty/vt/vt.c:4844
 vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline]
 vt_ioctl+0x2b6e/0x2fe0 drivers/tty/vt/vt_ioctl.c:751
 tty_ioctl+0xd18/0x1990 drivers/tty/tty_io.c:2803
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:904 [inline]
 __se_sys_ioctl+0x261/0x450 fs/ioctl.c:890
 __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:890
 x64_sys_call+0x1883/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 __kmalloc_large_node+0x231/0x370 mm/slub.c:3921
 __do_kmalloc_node mm/slub.c:3954 [inline]
 __kmalloc_node+0xb07/0x1060 mm/slub.c:3973
 kmalloc_node include/linux/slab.h:648 [inline]
 kvmalloc_node+0xc0/0x2d0 mm/util.c:634
 kvmalloc include/linux/slab.h:766 [inline]
 con_font_get drivers/tty/vt/vt.c:4719 [inline]
 con_font_op+0x659/0x1710 drivers/tty/vt/vt.c:4844
 vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline]
 vt_ioctl+0x2b6e/0x2fe0 drivers/tty/vt/vt_ioctl.c:751
 tty_ioctl+0xd18/0x1990 drivers/tty/tty_io.c:2803
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:904 [inline]
 __se_sys_ioctl+0x261/0x450 fs/ioctl.c:890
 __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:890
 x64_sys_call+0x1883/0x3b50 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Bytes 65536-81919 of 81920 are uninitialized
Memory access of size 81920 starts at ffff888073400000
Data copied to user address 00000000200001c0

CPU: 0 PID: 32400 Comm: syz-executor.1 Not tainted 6.9.0-rc6-syzkaller-00227-g3d25a941ea50 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
=====================================================


---
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