syzbot


KMSAN: kernel-infoleak in vcs_read

Status: fixed on 2018/07/13 11:20
Subsystems: serial
[Documentation on labels]
Fix commit: 21eff69aaaa0 vt: prevent leaking uninitialized data to userspace via /dev/vcs*
First crash: 2207d, last: 2197d
Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KMSAN: kernel-infoleak in vcs_read (2) serial C 1556 508d 1663d 22/27 fixed on 2023/02/24 13:50

Sample crash report:
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
==================================================================
BUG: KMSAN: kernel-infoleak in copy_to_user include/linux/uaccess.h:184 [inline]
BUG: KMSAN: kernel-infoleak in vcs_read+0x18ba/0x1cc0 drivers/tty/vt/vc_screen.c:352
CPU: 0 PID: 4540 Comm: syz-executor524 Not tainted 4.17.0+ #5
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+0x185/0x1d0 lib/dump_stack.c:113
 kmsan_report+0x188/0x2a0 mm/kmsan/kmsan.c:1117
 kmsan_internal_check_memory+0x138/0x1f0 mm/kmsan/kmsan.c:1211
 kmsan_copy_to_user+0x7a/0x160 mm/kmsan/kmsan.c:1253
 copy_to_user include/linux/uaccess.h:184 [inline]
 vcs_read+0x18ba/0x1cc0 drivers/tty/vt/vc_screen.c:352
 __vfs_read+0x1b2/0x9d0 fs/read_write.c:416
 vfs_read+0x36c/0x6b0 fs/read_write.c:452
 ksys_read fs/read_write.c:578 [inline]
 __do_sys_read fs/read_write.c:588 [inline]
 __se_sys_read fs/read_write.c:586 [inline]
 __x64_sys_read+0x1bf/0x3e0 fs/read_write.c:586
 do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x443d39
RSP: 002b:00007ffe1f341578 EFLAGS: 00000213 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000443d39
RDX: 00000000000000f0 RSI: 0000000020000400 RDI: 0000000000000003
RBP: 00000000006ce018 R08: 00000000004002e0 R09: 00000000004002e0
R10: 000000000000000f R11: 0000000000000213 R12: 00000000004019e0
R13: 0000000000401a70 R14: 0000000000000000 R15: 0000000000000000

Uninit was stored to memory at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279 [inline]
 kmsan_save_stack mm/kmsan/kmsan.c:294 [inline]
 kmsan_internal_chain_origin+0x12b/0x210 mm/kmsan/kmsan.c:685
 __msan_chain_origin+0x69/0xc0 mm/kmsan/kmsan_instr.c:464
 vcs_read+0xd01/0x1cc0 drivers/tty/vt/vc_screen.c:274
 __vfs_read+0x1b2/0x9d0 fs/read_write.c:416
 vfs_read+0x36c/0x6b0 fs/read_write.c:452
 ksys_read fs/read_write.c:578 [inline]
 __do_sys_read fs/read_write.c:588 [inline]
 __se_sys_read fs/read_write.c:586 [inline]
 __x64_sys_read+0x1bf/0x3e0 fs/read_write.c:586
 do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
Uninit was created at:
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:279 [inline]
 kmsan_internal_poison_shadow+0xb8/0x1b0 mm/kmsan/kmsan.c:189
 kmsan_kmalloc+0x94/0x100 mm/kmsan/kmsan.c:315
 __kmalloc+0x13a/0x350 mm/slub.c:3818
 kmalloc include/linux/slab.h:517 [inline]
 vc_allocate+0x438/0x800 drivers/tty/vt/vt.c:787
 con_install+0x8c/0x640 drivers/tty/vt/vt.c:2880
 tty_driver_install_tty drivers/tty/tty_io.c:1224 [inline]
 tty_init_dev+0x1b5/0x1020 drivers/tty/tty_io.c:1324
 tty_open_by_driver drivers/tty/tty_io.c:1959 [inline]
 tty_open+0x17b4/0x2ed0 drivers/tty/tty_io.c:2007
 chrdev_open+0xc25/0xd90 fs/char_dev.c:417
 do_dentry_open+0xccc/0x1440 fs/open.c:794
 vfs_open+0x1b6/0x2f0 fs/open.c:908
 do_last fs/namei.c:3365 [inline]
 path_openat+0x4771/0x6640 fs/namei.c:3506
 do_filp_open+0x261/0x640 fs/namei.c:3540
 do_sys_open+0x624/0x960 fs/open.c:1101
 __do_sys_open fs/open.c:1119 [inline]
 __se_sys_open fs/open.c:1114 [inline]
 __x64_sys_open+0xf2/0x130 fs/open.c:1114
 do_syscall_64+0x15b/0x230 arch/x86/entry/common.c:287
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Bytes 0-79 of 240 are uninitialized
Memory access starts at ffff8801925b8000
==================================================================

Crashes (531):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2018/06/08 22:22 https://github.com/google/kmsan.git master d6c351f832e3 866118af .config console log report syz C ci-upstream-kmsan-gce
2018/06/18 15:05 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/18 14:03 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/18 13:40 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/18 12:37 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/18 11:19 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/18 09:39 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/18 08:20 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/18 06:35 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/18 05:04 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/18 03:55 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/18 03:04 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/18 00:22 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 22:33 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 21:04 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 19:43 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 18:10 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 17:04 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 16:04 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 14:48 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 14:27 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 11:31 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 10:11 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 08:51 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 07:20 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 05:15 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 04:12 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 02:08 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/17 00:52 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 20:55 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 19:50 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 18:34 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 17:23 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 16:14 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 15:03 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 13:50 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 12:41 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 11:12 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 09:59 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 07:33 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 06:24 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/16 05:19 https://github.com/google/kmsan.git master 88e0e95b30f1 27c5f59f .config console log report ci-upstream-kmsan-gce
2018/06/08 15:05 https://github.com/google/kmsan.git master 6456f940990e f7b27b7a .config console log report ci-upstream-kmsan-gce
* Struck through repros no longer work on HEAD.