linux-kernel - KMSAN: uninit-value in do_update

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Message-ID: <00000000000090aa43059f773ca7@google.com>
Date:   Wed, 26 Feb 2020 01:29:09 -0800
From:   syzbot <syzbot+fd9351b459a0a1e53f37@...kaller.appspotmail.com>
To:     daniel.vetter@...ll.ch, ghalat@...hat.com, glider@...gle.com,
        gregkh@...uxfoundation.org, jslaby@...e.com,
        linux-kernel@...r.kernel.org, lukas@...ner.de,
        maarten.lankhorst@...ux.intel.com, okash.khawaja@...il.com,
        sam@...nborg.org, syzkaller-bugs@...glegroups.com
Subject: KMSAN: uninit-value in do_update_region

Hello,

syzbot found the following crash on:

HEAD commit:    8bbbc5cf kmsan: don't compile memmove
git tree:       https://github.com/google/kmsan.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=10a3e891e00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cd0e9a6b0e555cc3
dashboard link: https://syzkaller.appspot.com/bug?extid=fd9351b459a0a1e53f37
compiler:       clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
userspace arch: i386

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+fd9351b459a0a1e53f37@...kaller.appspotmail.com

=====================================================
BUG: KMSAN: uninit-value in do_update_region+0x6ef/0xb80 drivers/tty/vt/vt.c:665
CPU: 1 PID: 26865 Comm: syz-executor.3 Not tainted 5.6.0-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+0x1c9/0x220 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:118
 __msan_warning+0x58/0xa0 mm/kmsan/kmsan_instr.c:215
 do_update_region+0x6ef/0xb80 drivers/tty/vt/vt.c:665
 invert_screen+0x1088/0x1210 drivers/tty/vt/vt.c:794
 set_selection_kernel+0x2583/0x3400 drivers/tty/vt/selection.c:53
 set_selection_user+0x10a/0x150 drivers/tty/vt/selection.c:177
 tioclinux+0x589/0xc40 drivers/tty/vt/vt.c:3039
 vt_ioctl+0x1db1/0x5790 drivers/tty/vt/vt_ioctl.c:364
 vt_compat_ioctl+0x6f3/0x10c0 drivers/tty/vt/vt_ioctl.c:1232
 tty_compat_ioctl+0xa29/0x1850 drivers/tty/tty_io.c:2849
 __do_compat_sys_ioctl fs/ioctl.c:857 [inline]
 __se_compat_sys_ioctl+0x57c/0xed0 fs/ioctl.c:808
 __ia32_compat_sys_ioctl+0xd9/0x110 fs/ioctl.c:808
 do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
 do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
 entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f2cd99
Code: 90 e8 0b 00 00 00 f3 90 0f ae e8 eb f9 8d 74 26 00 89 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f5d270cc EFLAGS: 00000296 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000000541c
RDX: 0000000020000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
 kmsan_internal_chain_origin+0xad/0x130 mm/kmsan/kmsan.c:310
 __msan_chain_origin+0x50/0x90 mm/kmsan/kmsan_instr.c:165
 vgacon_invert_region+0x1f3/0x240 drivers/video/console/vgacon.c:675
 invert_screen+0x362/0x1210 drivers/tty/vt/vt.c:763
 set_selection_kernel+0x2583/0x3400 drivers/tty/vt/selection.c:53
 set_selection_user+0x10a/0x150 drivers/tty/vt/selection.c:177
 tioclinux+0x589/0xc40 drivers/tty/vt/vt.c:3039
 vt_ioctl+0x1db1/0x5790 drivers/tty/vt/vt_ioctl.c:364
 vt_compat_ioctl+0x6f3/0x10c0 drivers/tty/vt/vt_ioctl.c:1232
 tty_compat_ioctl+0xa29/0x1850 drivers/tty/tty_io.c:2849
 __do_compat_sys_ioctl fs/ioctl.c:857 [inline]
 __se_compat_sys_ioctl+0x57c/0xed0 fs/ioctl.c:808
 __ia32_compat_sys_ioctl+0xd9/0x110 fs/ioctl.c:808
 do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
 do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
 entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
 kmsan_internal_chain_origin+0xad/0x130 mm/kmsan/kmsan.c:310
 __msan_chain_origin+0x50/0x90 mm/kmsan/kmsan_instr.c:165
 vgacon_invert_region+0x1f3/0x240 drivers/video/console/vgacon.c:675
 invert_screen+0x362/0x1210 drivers/tty/vt/vt.c:763
 set_selection_kernel+0x2583/0x3400 drivers/tty/vt/selection.c:53
 set_selection_user+0x10a/0x150 drivers/tty/vt/selection.c:177
 tioclinux+0x589/0xc40 drivers/tty/vt/vt.c:3039
 vt_ioctl+0x1db1/0x5790 drivers/tty/vt/vt_ioctl.c:364
 vt_compat_ioctl+0x6f3/0x10c0 drivers/tty/vt/vt_ioctl.c:1232
 tty_compat_ioctl+0xa29/0x1850 drivers/tty/tty_io.c:2849
 __do_compat_sys_ioctl fs/ioctl.c:857 [inline]
 __se_compat_sys_ioctl+0x57c/0xed0 fs/ioctl.c:808
 __ia32_compat_sys_ioctl+0xd9/0x110 fs/ioctl.c:808
 do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
 do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
 entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139

Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:144 [inline]
 kmsan_internal_poison_shadow+0x66/0xd0 mm/kmsan/kmsan.c:127
 kmsan_slab_alloc+0x8a/0xe0 mm/kmsan/kmsan_hooks.c:82
 slab_alloc_node mm/slub.c:2793 [inline]
 slab_alloc mm/slub.c:2802 [inline]
 __kmalloc_track_caller+0x8ce/0xef0 mm/slub.c:4371
 kmemdup+0x95/0x140 mm/util.c:127
 ipv4_sysctl_init_net+0xa7/0x640 net/ipv4/sysctl_net_ipv4.c:1350
 ops_init+0x2d3/0x730 net/core/net_namespace.c:137
 setup_net+0x286/0x12b0 net/core/net_namespace.c:327
 copy_net_ns+0x551/0xa70 net/core/net_namespace.c:468
 create_new_namespaces+0x9a8/0x11e0 kernel/nsproxy.c:108
 unshare_nsproxy_namespaces+0x25e/0x340 kernel/nsproxy.c:229
 ksys_unshare+0x8d5/0x1120 kernel/fork.c:2957
 __do_sys_unshare kernel/fork.c:3025 [inline]
 __se_sys_unshare kernel/fork.c:3023 [inline]
 __ia32_sys_unshare+0x58/0x80 kernel/fork.c:3023
 do_syscall_32_irqs_on arch/x86/entry/common.c:339 [inline]
 do_fast_syscall_32+0x3c7/0x6e0 arch/x86/entry/common.c:410
 entry_SYSENTER_compat+0x68/0x77 arch/x86/entry/entry_64_compat.S:139
=====================================================


---
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