KMSAN: kernel-infoleak in vcs

KMSAN: kernel-infoleak in vcs_read (2)
Status: upstream: reported C repro on 2019/12/04 15:25
Reported-by: syzbot+31a641689d43387f05d3@syzkaller.appspotmail.com
First crash: 320d, last: 20h33m

similar bugs (1):
Kernel	Title	Repro	Bisected	Count	Last	Reported	Patched	Status
upstream	KMSAN: kernel-infoleak in vcs_read	C		531	854d	864d	9/17	fixed on 2018/07/13 11:20

Patch testing requests:
Created	Duration	User	Patch	Repo	Result
2020/09/30 20:23	3m	anant.thazhemadam@gmail.com	patch	https://github.com/google/kmsan.git master	error
2020/09/30 18:10	18m	anant.thazhemadam@gmail.com	patch	https://github.com/google/kmsan.git master	report log
2020/09/30 01:00	3m	anant.thazhemadam@gmail.com	patch	https://github.com/google/kmsan.git master	error

Sample crash report:

=====================================================
BUG: KMSAN: kernel-infoleak in kmsan_copy_to_user+0x81/0x90 mm/kmsan/kmsan_hooks.c:253
CPU: 0 PID: 8471 Comm: syz-executor446 Not tainted 5.8.0-rc5-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+0x21c/0x280 lib/dump_stack.c:118
 kmsan_report+0xf7/0x1e0 mm/kmsan/kmsan_report.c:121
 kmsan_internal_check_memory+0x19d/0x3d0 mm/kmsan/kmsan.c:443
 kmsan_copy_to_user+0x81/0x90 mm/kmsan/kmsan_hooks.c:253
 instrument_copy_to_user include/linux/instrumented.h:91 [inline]
 _copy_to_user+0x18e/0x260 lib/usercopy.c:33
 copy_to_user include/linux/uaccess.h:170 [inline]
 vcs_read+0x1c6f/0x2920 drivers/tty/vt/vc_screen.c:424
 vfs_read+0x577/0x14d0 fs/read_write.c:479
 ksys_read+0x275/0x500 fs/read_write.c:607
 __do_sys_read fs/read_write.c:617 [inline]
 __se_sys_read+0x92/0xb0 fs/read_write.c:615
 __x64_sys_read+0x4a/0x70 fs/read_write.c:615
 do_syscall_64+0xad/0x160 arch/x86/entry/common.c:386
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4453c9
Code: Bad RIP value.
RSP: 002b:00007fffa3c8af98 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004453c9
RDX: 0000000000002020 RSI: 0000000020000100 RDI: 0000000000000003
RBP: 0000000000022239 R08: 00000000004002e0 R09: 00000000004002e0
R10: 0000000000000004 R11: 0000000000000246 R12: 0000000000402590
R13: 0000000000402620 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
 kmsan_memcpy_memmove_metadata+0x272/0x2e0 mm/kmsan/kmsan.c:247
 kmsan_memcpy_metadata+0xb/0x10 mm/kmsan/kmsan.c:267
 __msan_memcpy+0x43/0x50 mm/kmsan/kmsan_instr.c:116
 vc_uniscr_copy_line+0x545/0x800 drivers/tty/vt/vt.c:572
 vcs_read+0x107d/0x2920 drivers/tty/vt/vc_screen.c:332
 vfs_read+0x577/0x14d0 fs/read_write.c:479
 ksys_read+0x275/0x500 fs/read_write.c:607
 __do_sys_read fs/read_write.c:617 [inline]
 __se_sys_read+0x92/0xb0 fs/read_write.c:615
 __x64_sys_read+0x4a/0x70 fs/read_write.c:615
 do_syscall_64+0xad/0x160 arch/x86/entry/common.c:386
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Uninit was created at:
 kmsan_save_stack_with_flags+0x3c/0x90 mm/kmsan/kmsan.c:144
 kmsan_internal_alloc_meta_for_pages mm/kmsan/kmsan_shadow.c:269 [inline]
 kmsan_alloc_page+0xc5/0x1a0 mm/kmsan/kmsan_shadow.c:293
 __alloc_pages_nodemask+0xdf0/0x1030 mm/page_alloc.c:4889
 alloc_pages_current+0x685/0xb50 mm/mempolicy.c:2292
 alloc_pages include/linux/gfp.h:545 [inline]
 __vmalloc_area_node mm/vmalloc.c:2489 [inline]
 __vmalloc_node_range+0x989/0x1400 mm/vmalloc.c:2555
 __vmalloc_node mm/vmalloc.c:2598 [inline]
 vmalloc+0xe0/0xf0 mm/vmalloc.c:2631
 vc_uniscr_alloc drivers/tty/vt/vt.c:354 [inline]
 vc_do_resize+0x73e/0x38f0 drivers/tty/vt/vt.c:1222
 vc_resize+0xc3/0xe0 drivers/tty/vt/vt.c:1334
 fbcon_modechanged+0xdc1/0x1320 drivers/video/fbdev/core/fbcon.c:2990
 fbcon_update_vcs+0x86/0xa0 drivers/video/fbdev/core/fbcon.c:3048
 fb_set_var+0x1420/0x1850 drivers/video/fbdev/core/fbmem.c:1056
 do_fb_ioctl+0xc00/0x1150 drivers/video/fbdev/core/fbmem.c:1109
 fb_ioctl+0x1e4/0x210 drivers/video/fbdev/core/fbmem.c:1185
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl fs/ioctl.c:753 [inline]
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl+0x319/0x4d0 fs/ioctl.c:760
 __x64_sys_ioctl+0x4a/0x70 fs/ioctl.c:760
 do_syscall_64+0xad/0x160 arch/x86/entry/common.c:386
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Bytes 0-319 of 640 are uninitialized
Memory access of size 640 starts at ffff8880bbb25000
Data copied to user address 0000000020000100
=====================================================

Crashes (39):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Maintainers
ci-upstream-kmsan-gce	2020/09/06 04:03	https://github.com/google/kmsan.git master	3b3ea602	abf9ba4f	.config	log	report	syz	C		gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/10/17 09:48	https://github.com/google/kmsan.git master	e67f4ba8	6e262c73	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/10/15 23:07	https://github.com/google/kmsan.git master	e67f4ba8	6e262c73	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/10/07 10:33	https://github.com/google/kmsan.git master	5edb1df2	1880b4a9	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/10/02 23:06	https://github.com/google/kmsan.git master	5edb1df2	4969d6ca	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/09/29 01:31	https://github.com/google/kmsan.git master	5edb1df2	1b88c6d5	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/09/18 16:13	https://github.com/google/kmsan.git master	c5a13b33	38962c8b	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/09/18 15:24	https://github.com/google/kmsan.git master	c5a13b33	38962c8b	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/09/06 00:42	https://github.com/google/kmsan.git master	3b3ea602	abf9ba4f	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/05/06 14:24	https://github.com/google/kmsan.git master	21c44613	4618eb2d	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/05/01 06:14	https://github.com/google/kmsan.git master	bfa90a4a	a4d01b80	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/04/25 01:56	https://github.com/google/kmsan.git master	9535d09e	03d97a1b	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/03/12 07:57	https://github.com/google/kmsan.git master	8bbbc5cf	d850e9d0	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, jwilk@jwilk.net, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/03/06 23:39	https://github.com/google/kmsan.git master	8bbbc5cf	fd2a5f28	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, jwilk@jwilk.net, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/02/08 22:29	https://github.com/google/kmsan.git master	686a4f77	06150bf1	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, jwilk@jwilk.net, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/02/08 11:25	https://github.com/google/kmsan.git master	686a4f77	06150bf1	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, jwilk@jwilk.net, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/01/29 17:28	https://github.com/google/kmsan.git master	686a4f77	5ed23f9a	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, jwilk@jwilk.net, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/01/29 16:08	https://github.com/google/kmsan.git master	686a4f77	5ed23f9a	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, jwilk@jwilk.net, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/01/15 16:22	https://github.com/google/kmsan.git master	686a4f77	069a5a44	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, jwilk@jwilk.net, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2020/01/03 10:40	https://github.com/google/kmsan.git master	997a8b55	9dcc1191	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, jwilk@jwilk.net, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2019/12/29 03:35	https://github.com/google/kmsan.git master	997a8b55	af6b8ef8	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, jwilk@jwilk.net, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce	2019/12/04 14:52	https://github.com/google/kmsan.git master	141b13f7	b2088328	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, jwilk@jwilk.net, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/10/19 15:53	https://github.com/google/kmsan.git master	e67f4ba8	ff4a3345	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/10/19 11:41	https://github.com/google/kmsan.git master	e67f4ba8	ff4a3345	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/10/18 12:24	https://github.com/google/kmsan.git master	e67f4ba8	fea47c01	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/10/16 17:04	https://github.com/google/kmsan.git master	e67f4ba8	6e262c73	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/10/16 10:33	https://github.com/google/kmsan.git master	e67f4ba8	6e262c73	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/10/16 10:11	https://github.com/google/kmsan.git master	e67f4ba8	6e262c73	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/10/12 07:48	https://github.com/google/kmsan.git master	e67f4ba8	4a77ae0b	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/10/11 05:32	https://github.com/google/kmsan.git master	e67f4ba8	4a77ae0b	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/10/08 19:10	https://github.com/google/kmsan.git master	5edb1df2	92390980	.config	log	report			info	gregkh@linuxfoundation.org, jirislaby@kernel.org, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/09/06 22:19	https://github.com/google/kmsan.git master	3b3ea602	abf9ba4f	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/09/06 18:58	https://github.com/google/kmsan.git master	3b3ea602	abf9ba4f	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/09/01 15:39	https://github.com/google/kmsan.git master	3b3ea602	d5a3ae1f	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/08/15 07:03	https://github.com/google/kmsan.git master	ce8056d1	424dd8e7	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/07/02 16:18	https://github.com/google/kmsan.git master	f0d5ec90	bed10395	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/06/14 06:43	https://github.com/google/kmsan.git master	f0d5ec90	a61674a5	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/04/12 13:13	https://github.com/google/kmsan.git master	75303409	36b0b050	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, linux-kernel@vger.kernel.org, nico@fluxnic.net
ci-upstream-kmsan-gce-386	2020/03/25 14:59	https://github.com/google/kmsan.git master	c95d0c95	41f049cc	.config	log	report				gregkh@linuxfoundation.org, jslaby@suse.com, jwilk@jwilk.net, linux-kernel@vger.kernel.org, nico@fluxnic.net