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* tty, fbcon: use-after-free in fbcon_invert_region
@ 2016-09-03 19:20 ` Dmitry Vyukov
  0 siblings, 0 replies; 14+ messages in thread
From: Dmitry Vyukov @ 2016-09-03 19:20 UTC (permalink / raw)
  To: Greg Kroah-Hartman, Peter Hurley, Jiri Slaby, LKML, plagnioj,
	tomi.valkeinen, jean-philippe.brucker, Scot Doyle, linux-fbdev,
	Eric W. Biederman
  Cc: syzkaller

Hello,

The following program causes use-after-free in fbcon_invert_region:

https://gist.githubusercontent.com/dvyukov/d657f9a9ca39f34c430dcf63ec1153ac/raw/04e1b94aef0fc9eb770d11373b568980ecaa7f34/gistfile1.txt

==================================================================
BUG: KASAN: use-after-free in fbcon_invert_region+0x1cc/0x1f0 at addr
ffff88006cc3f51e
Read of size 2 by task a.out/4240
CPU: 0 PID: 4240 Comm: a.out Not tainted 4.8.0-rc3-next-20160825+ #10
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
 ffffffff886b6fe0 ffff88003699f790 ffffffff82db3759 ffffffff8a0ae640
 fffffbfff10d6dfc ffff88003e800100 ffff88006cc3f500 ffff88006cc3f520
 0000000000000000 ffff88006cc3f51e ffff88003699f7b8 ffffffff81809e7c

Call Trace:
 [<ffffffff8180a474>] __asan_report_load2_noabort+0x14/0x20
mm/kasan/report.c:325
 [<ffffffff82fdbc8c>] fbcon_invert_region+0x1cc/0x1f0
drivers/video/console/fbcon.c:2750
 [<ffffffff8327ce72>] invert_screen+0x192/0x630 drivers/tty/vt/vt.c:470
 [<     inline     >] highlight drivers/tty/vt/selection.c:50
 [<ffffffff8326037c>] clear_selection+0x4c/0x60 drivers/tty/vt/selection.c:76
 [<ffffffff8327374e>] hide_cursor+0x24e/0x2d0 drivers/tty/vt/vt.c:599
 [<ffffffff83276207>] redraw_screen+0x2e7/0x840 drivers/tty/vt/vt.c:682
 [<ffffffff83278b0c>] vc_do_resize+0xebc/0x1160 drivers/tty/vt/vt.c:952
 [<ffffffff83278eba>] vt_resize+0xaa/0xe0 drivers/tty/vt/vt.c:992
 [<     inline     >] tiocswinsz drivers/tty/tty_io.c:2378
 [<ffffffff83224e71>] tty_ioctl+0x10c1/0x21e0 drivers/tty/tty_io.c:2892
 [<     inline     >] vfs_ioctl fs/ioctl.c:43
 [<ffffffff818a1c6c>] do_vfs_ioctl+0x18c/0x1080 fs/ioctl.c:675
 [<     inline     >] SYSC_ioctl fs/ioctl.c:690
 [<ffffffff818a2bef>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:681
 [<ffffffff86e10480>] entry_SYSCALL_64_fastpath+0x23/0xc1
arch/x86/entry/entry_64.S:208
Object at ffff88006cc3f500, in cache kmalloc-32 size: 32

Allocated:
PID = 3233
 [<     inline     >] kmalloc ./include/linux/slab.h:490
 [<     inline     >] kzalloc ./include/linux/slab.h:636
 [<ffffffff82b85834>] aa_alloc_task_context+0x54/0x90
security/apparmor/context.c:40
 [<ffffffff82b99e3d>] apparmor_cred_prepare+0x1d/0xb0 security/apparmor/lsm.c:76
 [<ffffffff82acf12d>] security_prepare_creds+0x7d/0xb0 security/security.c:912
 [<ffffffff813fb355>] prepare_kernel_cred+0x375/0x650 kernel/cred.c:630
 [<ffffffff813cded9>] call_usermodehelper_exec_async+0xb9/0x460
kernel/kmod.c:232
 [<ffffffff86e1070a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

Freed:
PID = 1693
 [<     inline     >] __cache_free mm/slab.c:3520
 [<ffffffff81807813>] kfree+0xc3/0x2a0 mm/slab.c:3837
 [<ffffffff8175f108>] kzfree+0x28/0x30 mm/slab_common.c:1323
 [<ffffffff82b85991>] aa_free_task_context+0x121/0x1d0
security/apparmor/context.c:54
 [<ffffffff82b99f79>] apparmor_cred_free+0x39/0x80 security/apparmor/lsm.c:51
 [<ffffffff82acf078>] security_cred_free+0x48/0x80 security/security.c:907
 [<ffffffff813f8224>] put_cred_rcu+0xe4/0x3e0 kernel/cred.c:116
 [<     inline     >] __rcu_reclaim kernel/rcu/rcu.h:118
 [<     inline     >] rcu_do_batch kernel/rcu/tree.c:2777
 [<     inline     >] invoke_rcu_callbacks kernel/rcu/tree.c:3041
 [<     inline     >] __rcu_process_callbacks kernel/rcu/tree.c:3008
 [<ffffffff814e7e3b>] rcu_process_callbacks+0xdbb/0x1560 kernel/rcu/tree.c:3025
 [<ffffffff86e1358c>] __do_softirq+0x25c/0xa3e kernel/softirq.c:273
Memory state around the buggy address:
 ffff88006cc3f400: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff88006cc3f480: 00 00 fc fc fc fc fc fc fb fb fb fb fc fc fc fc
>ffff88006cc3f500: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
                            ^
 ffff88006cc3f580: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff88006cc3f600: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================


I am also hitting similar bugs all over fbcon:

BUG: KASAN: slab-out-of-bounds in fbcon_putcs+0x444/0x4b0 at addr
ffff8800384e58a8

https://gist.githubusercontent.com/dvyukov/645a5f48b735fb384de7ea35fe1748ea/raw/3690a8b2c82a3b8fd7d07f4602a166f5756c3749/gistfile1.txt

BUG: KASAN: slab-out-of-bounds in bit_putcs+0xcd6/0xd70 at addr ffff88006abad8e6

https://gist.githubusercontent.com/dvyukov/2d909f2673eafbc35f7f17f95c395217/raw/83f4eb0193226d51c546015cddee4b6a697015b3/gistfile1.txt

BUG: KASAN: use-after-free in fbcon_putcs+0x444/0x4b0 at addr ffff8800644bd820

https://gist.githubusercontent.com/dvyukov/286cdf2d3f9c6956ec9055dad0cf7a2a/raw/f7e0a380be364afd0c2c4c54ff5661e451fb143d/gistfile1.txt

BUG: KASAN: slab-out-of-bounds in do_update_region+0x642/0x670 at addr
ffff8800661c56ac

https://gist.githubusercontent.com/dvyukov/7fd9d858ea38e8131e21a0377435c32c/raw/5d59989e05b4e39bb5ee90f49658674fa9db89ad/gistfile1.txt


On 0f98f121e1670eaa2a2fbb675e07d6ba7f0e146f of linux-next.

^ permalink raw reply	[flat|nested] 14+ messages in thread
* tty, fbcon: use-after-free in fbcon_invert_region
@ 2016-09-03 19:20 ` Dmitry Vyukov
  0 siblings, 0 replies; 14+ messages in thread
From: Dmitry Vyukov @ 2016-09-03 19:20 UTC (permalink / raw)
  To: Greg Kroah-Hartman, Peter Hurley, Jiri Slaby, LKML, plagnioj,
	tomi.valkeinen, jean-philippe.brucker, Scot Doyle, linux-fbdev,
	Eric W. Biederman
  Cc: syzkaller

Hello,

The following program causes use-after-free in fbcon_invert_region:

https://gist.githubusercontent.com/dvyukov/d657f9a9ca39f34c430dcf63ec1153ac/raw/04e1b94aef0fc9eb770d11373b568980ecaa7f34/gistfile1.txt

=================================
BUG: KASAN: use-after-free in fbcon_invert_region+0x1cc/0x1f0 at addr
ffff88006cc3f51e
Read of size 2 by task a.out/4240
CPU: 0 PID: 4240 Comm: a.out Not tainted 4.8.0-rc3-next-20160825+ #10
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
 ffffffff886b6fe0 ffff88003699f790 ffffffff82db3759 ffffffff8a0ae640
 fffffbfff10d6dfc ffff88003e800100 ffff88006cc3f500 ffff88006cc3f520
 0000000000000000 ffff88006cc3f51e ffff88003699f7b8 ffffffff81809e7c

Call Trace:
 [<ffffffff8180a474>] __asan_report_load2_noabort+0x14/0x20
mm/kasan/report.c:325
 [<ffffffff82fdbc8c>] fbcon_invert_region+0x1cc/0x1f0
drivers/video/console/fbcon.c:2750
 [<ffffffff8327ce72>] invert_screen+0x192/0x630 drivers/tty/vt/vt.c:470
 [<     inline     >] highlight drivers/tty/vt/selection.c:50
 [<ffffffff8326037c>] clear_selection+0x4c/0x60 drivers/tty/vt/selection.c:76
 [<ffffffff8327374e>] hide_cursor+0x24e/0x2d0 drivers/tty/vt/vt.c:599
 [<ffffffff83276207>] redraw_screen+0x2e7/0x840 drivers/tty/vt/vt.c:682
 [<ffffffff83278b0c>] vc_do_resize+0xebc/0x1160 drivers/tty/vt/vt.c:952
 [<ffffffff83278eba>] vt_resize+0xaa/0xe0 drivers/tty/vt/vt.c:992
 [<     inline     >] tiocswinsz drivers/tty/tty_io.c:2378
 [<ffffffff83224e71>] tty_ioctl+0x10c1/0x21e0 drivers/tty/tty_io.c:2892
 [<     inline     >] vfs_ioctl fs/ioctl.c:43
 [<ffffffff818a1c6c>] do_vfs_ioctl+0x18c/0x1080 fs/ioctl.c:675
 [<     inline     >] SYSC_ioctl fs/ioctl.c:690
 [<ffffffff818a2bef>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:681
 [<ffffffff86e10480>] entry_SYSCALL_64_fastpath+0x23/0xc1
arch/x86/entry/entry_64.S:208
Object at ffff88006cc3f500, in cache kmalloc-32 size: 32

Allocated:
PID = 3233
 [<     inline     >] kmalloc ./include/linux/slab.h:490
 [<     inline     >] kzalloc ./include/linux/slab.h:636
 [<ffffffff82b85834>] aa_alloc_task_context+0x54/0x90
security/apparmor/context.c:40
 [<ffffffff82b99e3d>] apparmor_cred_prepare+0x1d/0xb0 security/apparmor/lsm.c:76
 [<ffffffff82acf12d>] security_prepare_creds+0x7d/0xb0 security/security.c:912
 [<ffffffff813fb355>] prepare_kernel_cred+0x375/0x650 kernel/cred.c:630
 [<ffffffff813cded9>] call_usermodehelper_exec_async+0xb9/0x460
kernel/kmod.c:232
 [<ffffffff86e1070a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431

Freed:
PID = 1693
 [<     inline     >] __cache_free mm/slab.c:3520
 [<ffffffff81807813>] kfree+0xc3/0x2a0 mm/slab.c:3837
 [<ffffffff8175f108>] kzfree+0x28/0x30 mm/slab_common.c:1323
 [<ffffffff82b85991>] aa_free_task_context+0x121/0x1d0
security/apparmor/context.c:54
 [<ffffffff82b99f79>] apparmor_cred_free+0x39/0x80 security/apparmor/lsm.c:51
 [<ffffffff82acf078>] security_cred_free+0x48/0x80 security/security.c:907
 [<ffffffff813f8224>] put_cred_rcu+0xe4/0x3e0 kernel/cred.c:116
 [<     inline     >] __rcu_reclaim kernel/rcu/rcu.h:118
 [<     inline     >] rcu_do_batch kernel/rcu/tree.c:2777
 [<     inline     >] invoke_rcu_callbacks kernel/rcu/tree.c:3041
 [<     inline     >] __rcu_process_callbacks kernel/rcu/tree.c:3008
 [<ffffffff814e7e3b>] rcu_process_callbacks+0xdbb/0x1560 kernel/rcu/tree.c:3025
 [<ffffffff86e1358c>] __do_softirq+0x25c/0xa3e kernel/softirq.c:273
Memory state around the buggy address:
 ffff88006cc3f400: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff88006cc3f480: 00 00 fc fc fc fc fc fc fb fb fb fb fc fc fc fc
>ffff88006cc3f500: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
                            ^
 ffff88006cc3f580: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
 ffff88006cc3f600: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
=================================


I am also hitting similar bugs all over fbcon:

BUG: KASAN: slab-out-of-bounds in fbcon_putcs+0x444/0x4b0 at addr
ffff8800384e58a8

https://gist.githubusercontent.com/dvyukov/645a5f48b735fb384de7ea35fe1748ea/raw/3690a8b2c82a3b8fd7d07f4602a166f5756c3749/gistfile1.txt

BUG: KASAN: slab-out-of-bounds in bit_putcs+0xcd6/0xd70 at addr ffff88006abad8e6

https://gist.githubusercontent.com/dvyukov/2d909f2673eafbc35f7f17f95c395217/raw/83f4eb0193226d51c546015cddee4b6a697015b3/gistfile1.txt

BUG: KASAN: use-after-free in fbcon_putcs+0x444/0x4b0 at addr ffff8800644bd820

https://gist.githubusercontent.com/dvyukov/286cdf2d3f9c6956ec9055dad0cf7a2a/raw/f7e0a380be364afd0c2c4c54ff5661e451fb143d/gistfile1.txt

BUG: KASAN: slab-out-of-bounds in do_update_region+0x642/0x670 at addr
ffff8800661c56ac

https://gist.githubusercontent.com/dvyukov/7fd9d858ea38e8131e21a0377435c32c/raw/5d59989e05b4e39bb5ee90f49658674fa9db89ad/gistfile1.txt


On 0f98f121e1670eaa2a2fbb675e07d6ba7f0e146f of linux-next.

^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: tty, fbcon: use-after-free in fbcon_invert_region
  2016-09-03 19:20 ` Dmitry Vyukov
@ 2016-10-07 19:59   ` Dmitry Vyukov
  -1 siblings, 0 replies; 14+ messages in thread
From: Dmitry Vyukov @ 2016-10-07 19:59 UTC (permalink / raw)
  To: Greg Kroah-Hartman, Peter Hurley, Jiri Slaby, LKML, plagnioj,
	tomi.valkeinen, jean-philippe.brucker, Scot Doyle, linux-fbdev,
	Eric W. Biederman
  Cc: syzkaller

On Sat, Sep 3, 2016 at 9:20 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> Hello,
>
> The following program causes use-after-free in fbcon_invert_region:
>
> https://gist.githubusercontent.com/dvyukov/d657f9a9ca39f34c430dcf63ec1153ac/raw/04e1b94aef0fc9eb770d11373b568980ecaa7f34/gistfile1.txt
>
> ==================================================================
> BUG: KASAN: use-after-free in fbcon_invert_region+0x1cc/0x1f0 at addr
> ffff88006cc3f51e
> Read of size 2 by task a.out/4240
> CPU: 0 PID: 4240 Comm: a.out Not tainted 4.8.0-rc3-next-20160825+ #10
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>  ffffffff886b6fe0 ffff88003699f790 ffffffff82db3759 ffffffff8a0ae640
>  fffffbfff10d6dfc ffff88003e800100 ffff88006cc3f500 ffff88006cc3f520
>  0000000000000000 ffff88006cc3f51e ffff88003699f7b8 ffffffff81809e7c
>
> Call Trace:
>  [<ffffffff8180a474>] __asan_report_load2_noabort+0x14/0x20
> mm/kasan/report.c:325
>  [<ffffffff82fdbc8c>] fbcon_invert_region+0x1cc/0x1f0
> drivers/video/console/fbcon.c:2750
>  [<ffffffff8327ce72>] invert_screen+0x192/0x630 drivers/tty/vt/vt.c:470
>  [<     inline     >] highlight drivers/tty/vt/selection.c:50
>  [<ffffffff8326037c>] clear_selection+0x4c/0x60 drivers/tty/vt/selection.c:76
>  [<ffffffff8327374e>] hide_cursor+0x24e/0x2d0 drivers/tty/vt/vt.c:599
>  [<ffffffff83276207>] redraw_screen+0x2e7/0x840 drivers/tty/vt/vt.c:682
>  [<ffffffff83278b0c>] vc_do_resize+0xebc/0x1160 drivers/tty/vt/vt.c:952
>  [<ffffffff83278eba>] vt_resize+0xaa/0xe0 drivers/tty/vt/vt.c:992
>  [<     inline     >] tiocswinsz drivers/tty/tty_io.c:2378
>  [<ffffffff83224e71>] tty_ioctl+0x10c1/0x21e0 drivers/tty/tty_io.c:2892
>  [<     inline     >] vfs_ioctl fs/ioctl.c:43
>  [<ffffffff818a1c6c>] do_vfs_ioctl+0x18c/0x1080 fs/ioctl.c:675
>  [<     inline     >] SYSC_ioctl fs/ioctl.c:690
>  [<ffffffff818a2bef>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:681
>  [<ffffffff86e10480>] entry_SYSCALL_64_fastpath+0x23/0xc1
> arch/x86/entry/entry_64.S:208
> Object at ffff88006cc3f500, in cache kmalloc-32 size: 32
>
> Allocated:
> PID = 3233
>  [<     inline     >] kmalloc ./include/linux/slab.h:490
>  [<     inline     >] kzalloc ./include/linux/slab.h:636
>  [<ffffffff82b85834>] aa_alloc_task_context+0x54/0x90
> security/apparmor/context.c:40
>  [<ffffffff82b99e3d>] apparmor_cred_prepare+0x1d/0xb0 security/apparmor/lsm.c:76
>  [<ffffffff82acf12d>] security_prepare_creds+0x7d/0xb0 security/security.c:912
>  [<ffffffff813fb355>] prepare_kernel_cred+0x375/0x650 kernel/cred.c:630
>  [<ffffffff813cded9>] call_usermodehelper_exec_async+0xb9/0x460
> kernel/kmod.c:232
>  [<ffffffff86e1070a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
>
> Freed:
> PID = 1693
>  [<     inline     >] __cache_free mm/slab.c:3520
>  [<ffffffff81807813>] kfree+0xc3/0x2a0 mm/slab.c:3837
>  [<ffffffff8175f108>] kzfree+0x28/0x30 mm/slab_common.c:1323
>  [<ffffffff82b85991>] aa_free_task_context+0x121/0x1d0
> security/apparmor/context.c:54
>  [<ffffffff82b99f79>] apparmor_cred_free+0x39/0x80 security/apparmor/lsm.c:51
>  [<ffffffff82acf078>] security_cred_free+0x48/0x80 security/security.c:907
>  [<ffffffff813f8224>] put_cred_rcu+0xe4/0x3e0 kernel/cred.c:116
>  [<     inline     >] __rcu_reclaim kernel/rcu/rcu.h:118
>  [<     inline     >] rcu_do_batch kernel/rcu/tree.c:2777
>  [<     inline     >] invoke_rcu_callbacks kernel/rcu/tree.c:3041
>  [<     inline     >] __rcu_process_callbacks kernel/rcu/tree.c:3008
>  [<ffffffff814e7e3b>] rcu_process_callbacks+0xdbb/0x1560 kernel/rcu/tree.c:3025
>  [<ffffffff86e1358c>] __do_softirq+0x25c/0xa3e kernel/softirq.c:273
> Memory state around the buggy address:
>  ffff88006cc3f400: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>  ffff88006cc3f480: 00 00 fc fc fc fc fc fc fb fb fb fb fc fc fc fc
>>ffff88006cc3f500: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>                             ^
>  ffff88006cc3f580: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>  ffff88006cc3f600: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
> ==================================================================
>
>
> I am also hitting similar bugs all over fbcon:
>
> BUG: KASAN: slab-out-of-bounds in fbcon_putcs+0x444/0x4b0 at addr
> ffff8800384e58a8
>
> https://gist.githubusercontent.com/dvyukov/645a5f48b735fb384de7ea35fe1748ea/raw/3690a8b2c82a3b8fd7d07f4602a166f5756c3749/gistfile1.txt
>
> BUG: KASAN: slab-out-of-bounds in bit_putcs+0xcd6/0xd70 at addr ffff88006abad8e6
>
> https://gist.githubusercontent.com/dvyukov/2d909f2673eafbc35f7f17f95c395217/raw/83f4eb0193226d51c546015cddee4b6a697015b3/gistfile1.txt
>
> BUG: KASAN: use-after-free in fbcon_putcs+0x444/0x4b0 at addr ffff8800644bd820
>
> https://gist.githubusercontent.com/dvyukov/286cdf2d3f9c6956ec9055dad0cf7a2a/raw/f7e0a380be364afd0c2c4c54ff5661e451fb143d/gistfile1.txt
>
> BUG: KASAN: slab-out-of-bounds in do_update_region+0x642/0x670 at addr
> ffff8800661c56ac
>
> https://gist.githubusercontent.com/dvyukov/7fd9d858ea38e8131e21a0377435c32c/raw/5d59989e05b4e39bb5ee90f49658674fa9db89ad/gistfile1.txt
>
> On 0f98f121e1670eaa2a2fbb675e07d6ba7f0e146f of linux-next.


A friendly ping. This still happens at insane rate on
a6930aaee06755d1bdcfd943fbf614e4d92bb0c7 (Oct 5).

^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: tty, fbcon: use-after-free in fbcon_invert_region
@ 2016-10-07 19:59   ` Dmitry Vyukov
  0 siblings, 0 replies; 14+ messages in thread
From: Dmitry Vyukov @ 2016-10-07 19:59 UTC (permalink / raw)
  To: Greg Kroah-Hartman, Peter Hurley, Jiri Slaby, LKML, plagnioj,
	tomi.valkeinen, jean-philippe.brucker, Scot Doyle, linux-fbdev,
	Eric W. Biederman
  Cc: syzkaller

On Sat, Sep 3, 2016 at 9:20 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> Hello,
>
> The following program causes use-after-free in fbcon_invert_region:
>
> https://gist.githubusercontent.com/dvyukov/d657f9a9ca39f34c430dcf63ec1153ac/raw/04e1b94aef0fc9eb770d11373b568980ecaa7f34/gistfile1.txt
>
> =================================
> BUG: KASAN: use-after-free in fbcon_invert_region+0x1cc/0x1f0 at addr
> ffff88006cc3f51e
> Read of size 2 by task a.out/4240
> CPU: 0 PID: 4240 Comm: a.out Not tainted 4.8.0-rc3-next-20160825+ #10
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>  ffffffff886b6fe0 ffff88003699f790 ffffffff82db3759 ffffffff8a0ae640
>  fffffbfff10d6dfc ffff88003e800100 ffff88006cc3f500 ffff88006cc3f520
>  0000000000000000 ffff88006cc3f51e ffff88003699f7b8 ffffffff81809e7c
>
> Call Trace:
>  [<ffffffff8180a474>] __asan_report_load2_noabort+0x14/0x20
> mm/kasan/report.c:325
>  [<ffffffff82fdbc8c>] fbcon_invert_region+0x1cc/0x1f0
> drivers/video/console/fbcon.c:2750
>  [<ffffffff8327ce72>] invert_screen+0x192/0x630 drivers/tty/vt/vt.c:470
>  [<     inline     >] highlight drivers/tty/vt/selection.c:50
>  [<ffffffff8326037c>] clear_selection+0x4c/0x60 drivers/tty/vt/selection.c:76
>  [<ffffffff8327374e>] hide_cursor+0x24e/0x2d0 drivers/tty/vt/vt.c:599
>  [<ffffffff83276207>] redraw_screen+0x2e7/0x840 drivers/tty/vt/vt.c:682
>  [<ffffffff83278b0c>] vc_do_resize+0xebc/0x1160 drivers/tty/vt/vt.c:952
>  [<ffffffff83278eba>] vt_resize+0xaa/0xe0 drivers/tty/vt/vt.c:992
>  [<     inline     >] tiocswinsz drivers/tty/tty_io.c:2378
>  [<ffffffff83224e71>] tty_ioctl+0x10c1/0x21e0 drivers/tty/tty_io.c:2892
>  [<     inline     >] vfs_ioctl fs/ioctl.c:43
>  [<ffffffff818a1c6c>] do_vfs_ioctl+0x18c/0x1080 fs/ioctl.c:675
>  [<     inline     >] SYSC_ioctl fs/ioctl.c:690
>  [<ffffffff818a2bef>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:681
>  [<ffffffff86e10480>] entry_SYSCALL_64_fastpath+0x23/0xc1
> arch/x86/entry/entry_64.S:208
> Object at ffff88006cc3f500, in cache kmalloc-32 size: 32
>
> Allocated:
> PID = 3233
>  [<     inline     >] kmalloc ./include/linux/slab.h:490
>  [<     inline     >] kzalloc ./include/linux/slab.h:636
>  [<ffffffff82b85834>] aa_alloc_task_context+0x54/0x90
> security/apparmor/context.c:40
>  [<ffffffff82b99e3d>] apparmor_cred_prepare+0x1d/0xb0 security/apparmor/lsm.c:76
>  [<ffffffff82acf12d>] security_prepare_creds+0x7d/0xb0 security/security.c:912
>  [<ffffffff813fb355>] prepare_kernel_cred+0x375/0x650 kernel/cred.c:630
>  [<ffffffff813cded9>] call_usermodehelper_exec_async+0xb9/0x460
> kernel/kmod.c:232
>  [<ffffffff86e1070a>] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:431
>
> Freed:
> PID = 1693
>  [<     inline     >] __cache_free mm/slab.c:3520
>  [<ffffffff81807813>] kfree+0xc3/0x2a0 mm/slab.c:3837
>  [<ffffffff8175f108>] kzfree+0x28/0x30 mm/slab_common.c:1323
>  [<ffffffff82b85991>] aa_free_task_context+0x121/0x1d0
> security/apparmor/context.c:54
>  [<ffffffff82b99f79>] apparmor_cred_free+0x39/0x80 security/apparmor/lsm.c:51
>  [<ffffffff82acf078>] security_cred_free+0x48/0x80 security/security.c:907
>  [<ffffffff813f8224>] put_cred_rcu+0xe4/0x3e0 kernel/cred.c:116
>  [<     inline     >] __rcu_reclaim kernel/rcu/rcu.h:118
>  [<     inline     >] rcu_do_batch kernel/rcu/tree.c:2777
>  [<     inline     >] invoke_rcu_callbacks kernel/rcu/tree.c:3041
>  [<     inline     >] __rcu_process_callbacks kernel/rcu/tree.c:3008
>  [<ffffffff814e7e3b>] rcu_process_callbacks+0xdbb/0x1560 kernel/rcu/tree.c:3025
>  [<ffffffff86e1358c>] __do_softirq+0x25c/0xa3e kernel/softirq.c:273
> Memory state around the buggy address:
>  ffff88006cc3f400: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>  ffff88006cc3f480: 00 00 fc fc fc fc fc fc fb fb fb fb fc fc fc fc
>>ffff88006cc3f500: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>                             ^
>  ffff88006cc3f580: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>  ffff88006cc3f600: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
> =================================
>
>
> I am also hitting similar bugs all over fbcon:
>
> BUG: KASAN: slab-out-of-bounds in fbcon_putcs+0x444/0x4b0 at addr
> ffff8800384e58a8
>
> https://gist.githubusercontent.com/dvyukov/645a5f48b735fb384de7ea35fe1748ea/raw/3690a8b2c82a3b8fd7d07f4602a166f5756c3749/gistfile1.txt
>
> BUG: KASAN: slab-out-of-bounds in bit_putcs+0xcd6/0xd70 at addr ffff88006abad8e6
>
> https://gist.githubusercontent.com/dvyukov/2d909f2673eafbc35f7f17f95c395217/raw/83f4eb0193226d51c546015cddee4b6a697015b3/gistfile1.txt
>
> BUG: KASAN: use-after-free in fbcon_putcs+0x444/0x4b0 at addr ffff8800644bd820
>
> https://gist.githubusercontent.com/dvyukov/286cdf2d3f9c6956ec9055dad0cf7a2a/raw/f7e0a380be364afd0c2c4c54ff5661e451fb143d/gistfile1.txt
>
> BUG: KASAN: slab-out-of-bounds in do_update_region+0x642/0x670 at addr
> ffff8800661c56ac
>
> https://gist.githubusercontent.com/dvyukov/7fd9d858ea38e8131e21a0377435c32c/raw/5d59989e05b4e39bb5ee90f49658674fa9db89ad/gistfile1.txt
>
> On 0f98f121e1670eaa2a2fbb675e07d6ba7f0e146f of linux-next.


A friendly ping. This still happens at insane rate on
a6930aaee06755d1bdcfd943fbf614e4d92bb0c7 (Oct 5).

^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: tty, fbcon: use-after-free in fbcon_invert_region
  2016-10-07 19:59   ` Dmitry Vyukov
@ 2016-10-11  1:43     ` Scot Doyle
  -1 siblings, 0 replies; 14+ messages in thread
From: Scot Doyle @ 2016-10-11  1:43 UTC (permalink / raw)
  To: Dmitry Vyukov
  Cc: Greg Kroah-Hartman, Peter Hurley, Jiri Slaby, LKML, plagnioj,
	tomi.valkeinen, jean-philippe.brucker, linux-fbdev,
	Eric W. Biederman, syzkaller

On Fri, 7 Oct 2016, Dmitry Vyukov wrote:
> On Sat, Sep 3, 2016 at 9:20 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> > Hello,
> >
> > The following program causes use-after-free in fbcon_invert_region:
> >
> > https://gist.githubusercontent.com/dvyukov/d657f9a9ca39f34c430dcf63ec1153ac/raw/04e1b94aef0fc9eb770d11373b568980ecaa7f34/gistfile1.txt
> >
> > ==================================================================
> > BUG: KASAN: use-after-free in fbcon_invert_region+0x1cc/0x1f0 at addr
> > ffff88006cc3f51e
> > Read of size 2 by task a.out/4240
> > CPU: 0 PID: 4240 Comm: a.out Not tainted 4.8.0-rc3-next-20160825+ #10
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> >  ffffffff886b6fe0 ffff88003699f790 ffffffff82db3759 ffffffff8a0ae640
> >  fffffbfff10d6dfc ffff88003e800100 ffff88006cc3f500 ffff88006cc3f520
> >  0000000000000000 ffff88006cc3f51e ffff88003699f7b8 ffffffff81809e7c
> >
> > Call Trace:
> >  [<ffffffff8180a474>] __asan_report_load2_noabort+0x14/0x20
> > mm/kasan/report.c:325
> >  [<ffffffff82fdbc8c>] fbcon_invert_region+0x1cc/0x1f0
> > drivers/video/console/fbcon.c:2750
> >  [<ffffffff8327ce72>] invert_screen+0x192/0x630 drivers/tty/vt/vt.c:470
> >  [<     inline     >] highlight drivers/tty/vt/selection.c:50
> >  [<ffffffff8326037c>] clear_selection+0x4c/0x60 drivers/tty/vt/selection.c:76
> >  [<ffffffff8327374e>] hide_cursor+0x24e/0x2d0 drivers/tty/vt/vt.c:599
> >  [<ffffffff83276207>] redraw_screen+0x2e7/0x840 drivers/tty/vt/vt.c:682
> >  [<ffffffff83278b0c>] vc_do_resize+0xebc/0x1160 drivers/tty/vt/vt.c:952
> >  [<ffffffff83278eba>] vt_resize+0xaa/0xe0 drivers/tty/vt/vt.c:992
> >  [<     inline     >] tiocswinsz drivers/tty/tty_io.c:2378
> >  [<ffffffff83224e71>] tty_ioctl+0x10c1/0x21e0 drivers/tty/tty_io.c:2892
> >  [<     inline     >] vfs_ioctl fs/ioctl.c:43
> >  [<ffffffff818a1c6c>] do_vfs_ioctl+0x18c/0x1080 fs/ioctl.c:675
> >  [<     inline     >] SYSC_ioctl fs/ioctl.c:690
> >  [<ffffffff818a2bef>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:681
> >  [<ffffffff86e10480>] entry_SYSCALL_64_fastpath+0x23/0xc1

I wonder if the text selection is outside the newly resized vc?
Does this patch help?

--- vt.c	2016-10-11 00:32:43.079605599 -0000
+++ vt.c.new	2016-10-11 00:36:12.744650759 -0000
@@ -874,6 +874,9 @@
 	if (!newscreen)
 		return -ENOMEM;
 
+	if (vc == sel_cons)
+		clear_selection();
+
 	old_rows = vc->vc_rows;
 	old_row_size = vc->vc_size_row;
 

^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: tty, fbcon: use-after-free in fbcon_invert_region
@ 2016-10-11  1:43     ` Scot Doyle
  0 siblings, 0 replies; 14+ messages in thread
From: Scot Doyle @ 2016-10-11  1:43 UTC (permalink / raw)
  To: Dmitry Vyukov
  Cc: Greg Kroah-Hartman, Peter Hurley, Jiri Slaby, LKML, plagnioj,
	tomi.valkeinen, jean-philippe.brucker, linux-fbdev,
	Eric W. Biederman, syzkaller

On Fri, 7 Oct 2016, Dmitry Vyukov wrote:
> On Sat, Sep 3, 2016 at 9:20 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> > Hello,
> >
> > The following program causes use-after-free in fbcon_invert_region:
> >
> > https://gist.githubusercontent.com/dvyukov/d657f9a9ca39f34c430dcf63ec1153ac/raw/04e1b94aef0fc9eb770d11373b568980ecaa7f34/gistfile1.txt
> >
> > =================================
> > BUG: KASAN: use-after-free in fbcon_invert_region+0x1cc/0x1f0 at addr
> > ffff88006cc3f51e
> > Read of size 2 by task a.out/4240
> > CPU: 0 PID: 4240 Comm: a.out Not tainted 4.8.0-rc3-next-20160825+ #10
> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> >  ffffffff886b6fe0 ffff88003699f790 ffffffff82db3759 ffffffff8a0ae640
> >  fffffbfff10d6dfc ffff88003e800100 ffff88006cc3f500 ffff88006cc3f520
> >  0000000000000000 ffff88006cc3f51e ffff88003699f7b8 ffffffff81809e7c
> >
> > Call Trace:
> >  [<ffffffff8180a474>] __asan_report_load2_noabort+0x14/0x20
> > mm/kasan/report.c:325
> >  [<ffffffff82fdbc8c>] fbcon_invert_region+0x1cc/0x1f0
> > drivers/video/console/fbcon.c:2750
> >  [<ffffffff8327ce72>] invert_screen+0x192/0x630 drivers/tty/vt/vt.c:470
> >  [<     inline     >] highlight drivers/tty/vt/selection.c:50
> >  [<ffffffff8326037c>] clear_selection+0x4c/0x60 drivers/tty/vt/selection.c:76
> >  [<ffffffff8327374e>] hide_cursor+0x24e/0x2d0 drivers/tty/vt/vt.c:599
> >  [<ffffffff83276207>] redraw_screen+0x2e7/0x840 drivers/tty/vt/vt.c:682
> >  [<ffffffff83278b0c>] vc_do_resize+0xebc/0x1160 drivers/tty/vt/vt.c:952
> >  [<ffffffff83278eba>] vt_resize+0xaa/0xe0 drivers/tty/vt/vt.c:992
> >  [<     inline     >] tiocswinsz drivers/tty/tty_io.c:2378
> >  [<ffffffff83224e71>] tty_ioctl+0x10c1/0x21e0 drivers/tty/tty_io.c:2892
> >  [<     inline     >] vfs_ioctl fs/ioctl.c:43
> >  [<ffffffff818a1c6c>] do_vfs_ioctl+0x18c/0x1080 fs/ioctl.c:675
> >  [<     inline     >] SYSC_ioctl fs/ioctl.c:690
> >  [<ffffffff818a2bef>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:681
> >  [<ffffffff86e10480>] entry_SYSCALL_64_fastpath+0x23/0xc1

I wonder if the text selection is outside the newly resized vc?
Does this patch help?

--- vt.c	2016-10-11 00:32:43.079605599 -0000
+++ vt.c.new	2016-10-11 00:36:12.744650759 -0000
@@ -874,6 +874,9 @@
 	if (!newscreen)
 		return -ENOMEM;
 
+	if (vc = sel_cons)
+		clear_selection();
+
 	old_rows = vc->vc_rows;
 	old_row_size = vc->vc_size_row;
 


^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: tty, fbcon: use-after-free in fbcon_invert_region
  2016-10-11  1:43     ` Scot Doyle
@ 2016-10-11 13:31       ` Dmitry Vyukov
  -1 siblings, 0 replies; 14+ messages in thread
From: Dmitry Vyukov @ 2016-10-11 13:31 UTC (permalink / raw)
  To: syzkaller
  Cc: Greg Kroah-Hartman, Peter Hurley, Jiri Slaby, LKML, plagnioj,
	tomi.valkeinen, jean-philippe.brucker, linux-fbdev,
	Eric W. Biederman

On Tue, Oct 11, 2016 at 3:43 AM, Scot Doyle <lkml14@scotdoyle.com> wrote:
> On Fri, 7 Oct 2016, Dmitry Vyukov wrote:
>> On Sat, Sep 3, 2016 at 9:20 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
>> > Hello,
>> >
>> > The following program causes use-after-free in fbcon_invert_region:
>> >
>> > https://gist.githubusercontent.com/dvyukov/d657f9a9ca39f34c430dcf63ec1153ac/raw/04e1b94aef0fc9eb770d11373b568980ecaa7f34/gistfile1.txt
>> >
>> > ==================================================================
>> > BUG: KASAN: use-after-free in fbcon_invert_region+0x1cc/0x1f0 at addr
>> > ffff88006cc3f51e
>> > Read of size 2 by task a.out/4240
>> > CPU: 0 PID: 4240 Comm: a.out Not tainted 4.8.0-rc3-next-20160825+ #10
>> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>> >  ffffffff886b6fe0 ffff88003699f790 ffffffff82db3759 ffffffff8a0ae640
>> >  fffffbfff10d6dfc ffff88003e800100 ffff88006cc3f500 ffff88006cc3f520
>> >  0000000000000000 ffff88006cc3f51e ffff88003699f7b8 ffffffff81809e7c
>> >
>> > Call Trace:
>> >  [<ffffffff8180a474>] __asan_report_load2_noabort+0x14/0x20
>> > mm/kasan/report.c:325
>> >  [<ffffffff82fdbc8c>] fbcon_invert_region+0x1cc/0x1f0
>> > drivers/video/console/fbcon.c:2750
>> >  [<ffffffff8327ce72>] invert_screen+0x192/0x630 drivers/tty/vt/vt.c:470
>> >  [<     inline     >] highlight drivers/tty/vt/selection.c:50
>> >  [<ffffffff8326037c>] clear_selection+0x4c/0x60 drivers/tty/vt/selection.c:76
>> >  [<ffffffff8327374e>] hide_cursor+0x24e/0x2d0 drivers/tty/vt/vt.c:599
>> >  [<ffffffff83276207>] redraw_screen+0x2e7/0x840 drivers/tty/vt/vt.c:682
>> >  [<ffffffff83278b0c>] vc_do_resize+0xebc/0x1160 drivers/tty/vt/vt.c:952
>> >  [<ffffffff83278eba>] vt_resize+0xaa/0xe0 drivers/tty/vt/vt.c:992
>> >  [<     inline     >] tiocswinsz drivers/tty/tty_io.c:2378
>> >  [<ffffffff83224e71>] tty_ioctl+0x10c1/0x21e0 drivers/tty/tty_io.c:2892
>> >  [<     inline     >] vfs_ioctl fs/ioctl.c:43
>> >  [<ffffffff818a1c6c>] do_vfs_ioctl+0x18c/0x1080 fs/ioctl.c:675
>> >  [<     inline     >] SYSC_ioctl fs/ioctl.c:690
>> >  [<ffffffff818a2bef>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:681
>> >  [<ffffffff86e10480>] entry_SYSCALL_64_fastpath+0x23/0xc1
>
> I wonder if the text selection is outside the newly resized vc?
> Does this patch help?
>
> --- vt.c        2016-10-11 00:32:43.079605599 -0000
> +++ vt.c.new    2016-10-11 00:36:12.744650759 -0000
> @@ -874,6 +874,9 @@
>         if (!newscreen)
>                 return -ENOMEM;
>
> +       if (vc == sel_cons)
> +               clear_selection();
> +
>         old_rows = vc->vc_rows;
>         old_row_size = vc->vc_size_row;


This helped with the use-after-frees and out-of-bounds.

Tested-by: Dmitry Vyukov <dvyukov@google.com>



However, now the test program hanged in D unkillable stack on some
kind of kernel deadlock. Don't know if it's induced by your patch, or
just another bug. At least there are no vc_do_resize in stacks.

# ps afxu | grep a.out
root      6163  6.5  0.0      0     0 pts/0    Zl   13:25   0:00  |
   \_ [a.out] <defunct>

# ls /proc/6163/task/
6163  6191  6193  6194 6201

# cat /proc/6163/task/*/stack
[<     inline     >] down_read_failed drivers/tty/tty_ldsem.c:241
[<ffffffff831b8da6>] __ldsem_down_read_nested+0x2a6/0x5b0
drivers/tty/tty_ldsem.c:332
[<ffffffff831b23f5>] tty_ldisc_ref_wait+0x35/0xb0 drivers/tty/tty_ldisc.c:274
[<ffffffff831962b7>] tty_write+0x177/0x840 drivers/tty/tty_io.c:1250
[<ffffffff8182c700>] __vfs_write+0x110/0x620 fs/read_write.c:510
[<ffffffff8182dc05>] vfs_write+0x175/0x4e0 fs/read_write.c:560
[<     inline     >] SYSC_write fs/read_write.c:607
[<ffffffff818314c9>] SyS_write+0xd9/0x1b0 fs/read_write.c:599
[<ffffffff86daf545>] entry_SYSCALL_64_fastpath+0x23/0xc6
arch/x86/entry/entry_64.S:208
[<ffffffffffffffff>] 0xffffffffffffffff
[<     inline     >] down_read_failed drivers/tty/tty_ldsem.c:241
[<ffffffff831b8da6>] __ldsem_down_read_nested+0x2a6/0x5b0
drivers/tty/tty_ldsem.c:332
[<ffffffff831b23f5>] tty_ldisc_ref_wait+0x35/0xb0 drivers/tty/tty_ldisc.c:274
[<ffffffff831962b7>] tty_write+0x177/0x840 drivers/tty/tty_io.c:1250
[<ffffffff8182c700>] __vfs_write+0x110/0x620 fs/read_write.c:510
[<ffffffff8182dc05>] vfs_write+0x175/0x4e0 fs/read_write.c:560
[<     inline     >] SYSC_write fs/read_write.c:607
[<ffffffff818314c9>] SyS_write+0xd9/0x1b0 fs/read_write.c:599
[<ffffffff86daf545>] entry_SYSCALL_64_fastpath+0x23/0xc6
arch/x86/entry/entry_64.S:208
[<ffffffffffffffff>] 0xffffffffffffffff
[<     inline     >] down_read_failed drivers/tty/tty_ldsem.c:241
[<ffffffff831b8da6>] __ldsem_down_read_nested+0x2a6/0x5b0
drivers/tty/tty_ldsem.c:332
[<ffffffff831b23f5>] tty_ldisc_ref_wait+0x35/0xb0 drivers/tty/tty_ldisc.c:274
[<ffffffff831962b7>] tty_write+0x177/0x840 drivers/tty/tty_io.c:1250
[<ffffffff8182c700>] __vfs_write+0x110/0x620 fs/read_write.c:510
[<ffffffff8182dc05>] vfs_write+0x175/0x4e0 fs/read_write.c:560
[<     inline     >] SYSC_write fs/read_write.c:607
[<ffffffff818314c9>] SyS_write+0xd9/0x1b0 fs/read_write.c:599
[<ffffffff86daf545>] entry_SYSCALL_64_fastpath+0x23/0xc6
arch/x86/entry/entry_64.S:208
[<ffffffffffffffff>] 0xffffffffffffffff
[<     inline     >] down_read_failed drivers/tty/tty_ldsem.c:241
[<ffffffff831b8da6>] __ldsem_down_read_nested+0x2a6/0x5b0
drivers/tty/tty_ldsem.c:332
[<ffffffff831b23f5>] tty_ldisc_ref_wait+0x35/0xb0 drivers/tty/tty_ldisc.c:274
[<ffffffff8319def3>] tty_ioctl+0xc53/0x2180 drivers/tty/tty_io.c:2987
[<     inline     >] vfs_ioctl fs/ioctl.c:43
[<ffffffff8186bc31>] do_vfs_ioctl+0x191/0x1050 fs/ioctl.c:679
[<     inline     >] SYSC_ioctl fs/ioctl.c:694
[<ffffffff8186cb84>] SyS_ioctl+0x94/0xc0 fs/ioctl.c:685
[<ffffffff86daf545>] entry_SYSCALL_64_fastpath+0x23/0xc6
arch/x86/entry/entry_64.S:208
[<ffffffffffffffff>] 0xffffffffffffffff

# cat /proc/6191/status
Name: a.out
Umask: 0022
State: D (disk sleep)
Tgid: 6163
Ngid: 0
Pid: 6191
PPid: 6154
TracerPid: 0
Uid: 0 0 0 0
Gid: 0 0 0 0
FDSize: 256
Groups: 0
NStgid: 6163
NSpid: 6191
NSpgid: 6163
NSsid: 6154
VmPeak:  402244 kB
VmSize:  402244 kB
VmLck:       0 kB
VmPin:       0 kB
VmHWM:    3140 kB
VmRSS:    3140 kB
RssAnon:    2508 kB
RssFile:     632 kB
RssShmem:       0 kB
VmData:  401072 kB
VmStk:     136 kB
VmExe:     832 kB
VmLib:       8 kB
VmPTE:     212 kB
VmPMD:      12 kB
VmSwap:       0 kB
HugetlbPages:       0 kB
Threads: 5
SigQ: 1/3150
SigPnd: 0000000000000100
ShdPnd: 0000000000000100
SigBlk: 0000000000000000
SigIgn: 0000000000000000
SigCgt: 0000000180000440
CapInh: 0000000000000000
CapPrm: 0000003fffffffff
CapEff: 0000003fffffffff
CapBnd: 0000003fffffffff
CapAmb: 0000000000000000
Seccomp: 0
Cpus_allowed: f
Cpus_allowed_list: 0-3
Mems_allowed: 00000000,00000003
Mems_allowed_list: 0-1
voluntary_ctxt_switches: 1
nonvoluntary_ctxt_switches: 0

^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: tty, fbcon: use-after-free in fbcon_invert_region
@ 2016-10-11 13:31       ` Dmitry Vyukov
  0 siblings, 0 replies; 14+ messages in thread
From: Dmitry Vyukov @ 2016-10-11 13:31 UTC (permalink / raw)
  To: syzkaller
  Cc: Greg Kroah-Hartman, Peter Hurley, Jiri Slaby, LKML, plagnioj,
	tomi.valkeinen, jean-philippe.brucker, linux-fbdev,
	Eric W. Biederman

On Tue, Oct 11, 2016 at 3:43 AM, Scot Doyle <lkml14@scotdoyle.com> wrote:
> On Fri, 7 Oct 2016, Dmitry Vyukov wrote:
>> On Sat, Sep 3, 2016 at 9:20 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
>> > Hello,
>> >
>> > The following program causes use-after-free in fbcon_invert_region:
>> >
>> > https://gist.githubusercontent.com/dvyukov/d657f9a9ca39f34c430dcf63ec1153ac/raw/04e1b94aef0fc9eb770d11373b568980ecaa7f34/gistfile1.txt
>> >
>> > =================================
>> > BUG: KASAN: use-after-free in fbcon_invert_region+0x1cc/0x1f0 at addr
>> > ffff88006cc3f51e
>> > Read of size 2 by task a.out/4240
>> > CPU: 0 PID: 4240 Comm: a.out Not tainted 4.8.0-rc3-next-20160825+ #10
>> > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
>> >  ffffffff886b6fe0 ffff88003699f790 ffffffff82db3759 ffffffff8a0ae640
>> >  fffffbfff10d6dfc ffff88003e800100 ffff88006cc3f500 ffff88006cc3f520
>> >  0000000000000000 ffff88006cc3f51e ffff88003699f7b8 ffffffff81809e7c
>> >
>> > Call Trace:
>> >  [<ffffffff8180a474>] __asan_report_load2_noabort+0x14/0x20
>> > mm/kasan/report.c:325
>> >  [<ffffffff82fdbc8c>] fbcon_invert_region+0x1cc/0x1f0
>> > drivers/video/console/fbcon.c:2750
>> >  [<ffffffff8327ce72>] invert_screen+0x192/0x630 drivers/tty/vt/vt.c:470
>> >  [<     inline     >] highlight drivers/tty/vt/selection.c:50
>> >  [<ffffffff8326037c>] clear_selection+0x4c/0x60 drivers/tty/vt/selection.c:76
>> >  [<ffffffff8327374e>] hide_cursor+0x24e/0x2d0 drivers/tty/vt/vt.c:599
>> >  [<ffffffff83276207>] redraw_screen+0x2e7/0x840 drivers/tty/vt/vt.c:682
>> >  [<ffffffff83278b0c>] vc_do_resize+0xebc/0x1160 drivers/tty/vt/vt.c:952
>> >  [<ffffffff83278eba>] vt_resize+0xaa/0xe0 drivers/tty/vt/vt.c:992
>> >  [<     inline     >] tiocswinsz drivers/tty/tty_io.c:2378
>> >  [<ffffffff83224e71>] tty_ioctl+0x10c1/0x21e0 drivers/tty/tty_io.c:2892
>> >  [<     inline     >] vfs_ioctl fs/ioctl.c:43
>> >  [<ffffffff818a1c6c>] do_vfs_ioctl+0x18c/0x1080 fs/ioctl.c:675
>> >  [<     inline     >] SYSC_ioctl fs/ioctl.c:690
>> >  [<ffffffff818a2bef>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:681
>> >  [<ffffffff86e10480>] entry_SYSCALL_64_fastpath+0x23/0xc1
>
> I wonder if the text selection is outside the newly resized vc?
> Does this patch help?
>
> --- vt.c        2016-10-11 00:32:43.079605599 -0000
> +++ vt.c.new    2016-10-11 00:36:12.744650759 -0000
> @@ -874,6 +874,9 @@
>         if (!newscreen)
>                 return -ENOMEM;
>
> +       if (vc = sel_cons)
> +               clear_selection();
> +
>         old_rows = vc->vc_rows;
>         old_row_size = vc->vc_size_row;


This helped with the use-after-frees and out-of-bounds.

Tested-by: Dmitry Vyukov <dvyukov@google.com>



However, now the test program hanged in D unkillable stack on some
kind of kernel deadlock. Don't know if it's induced by your patch, or
just another bug. At least there are no vc_do_resize in stacks.

# ps afxu | grep a.out
root      6163  6.5  0.0      0     0 pts/0    Zl   13:25   0:00  |
   \_ [a.out] <defunct>

# ls /proc/6163/task/
6163  6191  6193  6194 6201

# cat /proc/6163/task/*/stack
[<     inline     >] down_read_failed drivers/tty/tty_ldsem.c:241
[<ffffffff831b8da6>] __ldsem_down_read_nested+0x2a6/0x5b0
drivers/tty/tty_ldsem.c:332
[<ffffffff831b23f5>] tty_ldisc_ref_wait+0x35/0xb0 drivers/tty/tty_ldisc.c:274
[<ffffffff831962b7>] tty_write+0x177/0x840 drivers/tty/tty_io.c:1250
[<ffffffff8182c700>] __vfs_write+0x110/0x620 fs/read_write.c:510
[<ffffffff8182dc05>] vfs_write+0x175/0x4e0 fs/read_write.c:560
[<     inline     >] SYSC_write fs/read_write.c:607
[<ffffffff818314c9>] SyS_write+0xd9/0x1b0 fs/read_write.c:599
[<ffffffff86daf545>] entry_SYSCALL_64_fastpath+0x23/0xc6
arch/x86/entry/entry_64.S:208
[<ffffffffffffffff>] 0xffffffffffffffff
[<     inline     >] down_read_failed drivers/tty/tty_ldsem.c:241
[<ffffffff831b8da6>] __ldsem_down_read_nested+0x2a6/0x5b0
drivers/tty/tty_ldsem.c:332
[<ffffffff831b23f5>] tty_ldisc_ref_wait+0x35/0xb0 drivers/tty/tty_ldisc.c:274
[<ffffffff831962b7>] tty_write+0x177/0x840 drivers/tty/tty_io.c:1250
[<ffffffff8182c700>] __vfs_write+0x110/0x620 fs/read_write.c:510
[<ffffffff8182dc05>] vfs_write+0x175/0x4e0 fs/read_write.c:560
[<     inline     >] SYSC_write fs/read_write.c:607
[<ffffffff818314c9>] SyS_write+0xd9/0x1b0 fs/read_write.c:599
[<ffffffff86daf545>] entry_SYSCALL_64_fastpath+0x23/0xc6
arch/x86/entry/entry_64.S:208
[<ffffffffffffffff>] 0xffffffffffffffff
[<     inline     >] down_read_failed drivers/tty/tty_ldsem.c:241
[<ffffffff831b8da6>] __ldsem_down_read_nested+0x2a6/0x5b0
drivers/tty/tty_ldsem.c:332
[<ffffffff831b23f5>] tty_ldisc_ref_wait+0x35/0xb0 drivers/tty/tty_ldisc.c:274
[<ffffffff831962b7>] tty_write+0x177/0x840 drivers/tty/tty_io.c:1250
[<ffffffff8182c700>] __vfs_write+0x110/0x620 fs/read_write.c:510
[<ffffffff8182dc05>] vfs_write+0x175/0x4e0 fs/read_write.c:560
[<     inline     >] SYSC_write fs/read_write.c:607
[<ffffffff818314c9>] SyS_write+0xd9/0x1b0 fs/read_write.c:599
[<ffffffff86daf545>] entry_SYSCALL_64_fastpath+0x23/0xc6
arch/x86/entry/entry_64.S:208
[<ffffffffffffffff>] 0xffffffffffffffff
[<     inline     >] down_read_failed drivers/tty/tty_ldsem.c:241
[<ffffffff831b8da6>] __ldsem_down_read_nested+0x2a6/0x5b0
drivers/tty/tty_ldsem.c:332
[<ffffffff831b23f5>] tty_ldisc_ref_wait+0x35/0xb0 drivers/tty/tty_ldisc.c:274
[<ffffffff8319def3>] tty_ioctl+0xc53/0x2180 drivers/tty/tty_io.c:2987
[<     inline     >] vfs_ioctl fs/ioctl.c:43
[<ffffffff8186bc31>] do_vfs_ioctl+0x191/0x1050 fs/ioctl.c:679
[<     inline     >] SYSC_ioctl fs/ioctl.c:694
[<ffffffff8186cb84>] SyS_ioctl+0x94/0xc0 fs/ioctl.c:685
[<ffffffff86daf545>] entry_SYSCALL_64_fastpath+0x23/0xc6
arch/x86/entry/entry_64.S:208
[<ffffffffffffffff>] 0xffffffffffffffff

# cat /proc/6191/status
Name: a.out
Umask: 0022
State: D (disk sleep)
Tgid: 6163
Ngid: 0
Pid: 6191
PPid: 6154
TracerPid: 0
Uid: 0 0 0 0
Gid: 0 0 0 0
FDSize: 256
Groups: 0
NStgid: 6163
NSpid: 6191
NSpgid: 6163
NSsid: 6154
VmPeak:  402244 kB
VmSize:  402244 kB
VmLck:       0 kB
VmPin:       0 kB
VmHWM:    3140 kB
VmRSS:    3140 kB
RssAnon:    2508 kB
RssFile:     632 kB
RssShmem:       0 kB
VmData:  401072 kB
VmStk:     136 kB
VmExe:     832 kB
VmLib:       8 kB
VmPTE:     212 kB
VmPMD:      12 kB
VmSwap:       0 kB
HugetlbPages:       0 kB
Threads: 5
SigQ: 1/3150
SigPnd: 0000000000000100
ShdPnd: 0000000000000100
SigBlk: 0000000000000000
SigIgn: 0000000000000000
SigCgt: 0000000180000440
CapInh: 0000000000000000
CapPrm: 0000003fffffffff
CapEff: 0000003fffffffff
CapBnd: 0000003fffffffff
CapAmb: 0000000000000000
Seccomp: 0
Cpus_allowed: f
Cpus_allowed_list: 0-3
Mems_allowed: 00000000,00000003
Mems_allowed_list: 0-1
voluntary_ctxt_switches: 1
nonvoluntary_ctxt_switches: 0

^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: tty, fbcon: use-after-free in fbcon_invert_region
  2016-10-07 19:59   ` Dmitry Vyukov
@ 2016-10-11 22:48     ` Scot Doyle
  -1 siblings, 0 replies; 14+ messages in thread
From: Scot Doyle @ 2016-10-11 22:48 UTC (permalink / raw)
  To: Dmitry Vyukov
  Cc: Greg Kroah-Hartman, Peter Hurley, Jiri Slaby, linux-kernel,
	plagnioj, tomi.valkeinen, jean-philippe.brucker, linux-fbdev,
	Eric W. Biederman, syzkaller

> On Tue, Oct 11, 2016 at 3:43 AM, Scot Doyle <lkml14@scotdoyle.com> wrote:
> > I wonder if the text selection is outside the newly resized vc?
> > Does this patch help?
> > 
> > --- vt.c        2016-10-11 00:32:43.079605599 -0000
> > +++ vt.c.new    2016-10-11 00:36:12.744650759 -0000
> > @@ -874,6 +874,9 @@
> > if (!newscreen)
> > return -ENOMEM;
> > 
> > +       if (vc == sel_cons)
> > +               clear_selection();
> > +
> > old_rows = vc->vc_rows;
> > old_row_size = vc->vc_size_row;
>
> This helped with the use-after-frees and out-of-bounds.
> Tested-by: Dmitry Vyukov <dvyukov@google.com>
>
> However, now the test program hanged in D unkillable stack on some
> kind of kernel deadlock. Don't know if it's induced by your patch, or
> just another bug. At least there are no vc_do_resize in stacks.
>
> # ps afxu | grep a.out
> root      6163  6.5  0.0      0     0 pts/0    Zl   13:25   0:00  |
>    \_ [a.out] <defunct>
>
> # ls /proc/6163/task/
> 6163  6191  6193  6194 6201
> 
> # cat /proc/6163/task/*/stack
> [<     inline     >] down_read_failed drivers/tty/tty_ldsem.c:241
> [<ffffffff831b8da6>] __ldsem_down_read_nested+0x2a6/0x5b0 drivers/tty/tty_ldsem.c:332
> [<ffffffff831b23f5>] tty_ldisc_ref_wait+0x35/0xb0 drivers/tty/tty_ldisc.c:274
> [<ffffffff831962b7>] tty_write+0x177/0x840 drivers/tty/tty_io.c:1250
> [<ffffffff8182c700>] __vfs_write+0x110/0x620 fs/read_write.c:510
> [<ffffffff8182dc05>] vfs_write+0x175/0x4e0 fs/read_write.c:560
> [<     inline     >] SYSC_write fs/read_write.c:607
> [<ffffffff818314c9>] SyS_write+0xd9/0x1b0 fs/read_write.c:599
> [<ffffffff86daf545>] entry_SYSCALL_64_fastpath+0x23/0xc6
> arch/x86/entry/entry_64.S:208

The patch below removes the resize ioctl's from the first test program. 
Are there any use-after-free/out-of-bounds errors when running the patched 
test program on the unpatched kernel? If not, but there are still 
deadlocks, then perhaps they aren't caused by the proposed kernel patch?

--- test.c
+++ test.c.new
@@ -141,8 +141,6 @@
     NONFAILING(*(uint16_t*)0x20f77ff9 = (uint16_t)0x6);
     NONFAILING(*(uint16_t*)0x20f77ffb = (uint16_t)0x3f);
     NONFAILING(*(uint16_t*)0x20f77ffd = (uint16_t)0x0);
-    r[17] = execute_syscall(__NR_ioctl, r[8], 0x541cul, 0x20f77ff4ul, 0,
-                            0, 0, 0, 0, 0);
     break;
   case 8:
     NONFAILING(*(uint32_t*)0x20f6dffc = (uint32_t)0x5);
@@ -212,8 +210,6 @@
     NONFAILING(*(uint16_t*)0x20f78ffa = (uint16_t)0xeb8);
     NONFAILING(*(uint16_t*)0x20f78ffc = (uint16_t)0x9);
     NONFAILING(*(uint16_t*)0x20f78ffe = (uint16_t)0x7);
-    r2[17] = execute_syscall(__NR_ioctl, r2[5], 0x5609ul, 0x20f78ffaul, 0,
-                            0, 0, 0, 0, 0);
     break;
   case 8:
     r2[18] =
@@ -273,8 +269,6 @@
     NONFAILING(*(uint16_t*)0x20f70002 = (uint16_t)0x2);
     NONFAILING(*(uint16_t*)0x20f70004 = (uint16_t)0xd1e);
     NONFAILING(*(uint16_t*)0x20f70006 = (uint16_t)0x7);
-    r2[34] = execute_syscall(__NR_ioctl, r2[5], 0x5414ul, 0x20f70000ul, 0,
-                            0, 0, 0, 0, 0);
     break;
   }
   return 0;

^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: tty, fbcon: use-after-free in fbcon_invert_region
@ 2016-10-11 22:48     ` Scot Doyle
  0 siblings, 0 replies; 14+ messages in thread
From: Scot Doyle @ 2016-10-11 22:48 UTC (permalink / raw)
  To: Dmitry Vyukov
  Cc: Greg Kroah-Hartman, Peter Hurley, Jiri Slaby, linux-kernel,
	plagnioj, tomi.valkeinen, jean-philippe.brucker, linux-fbdev,
	Eric W. Biederman, syzkaller

> On Tue, Oct 11, 2016 at 3:43 AM, Scot Doyle <lkml14@scotdoyle.com> wrote:
> > I wonder if the text selection is outside the newly resized vc?
> > Does this patch help?
> > 
> > --- vt.c        2016-10-11 00:32:43.079605599 -0000
> > +++ vt.c.new    2016-10-11 00:36:12.744650759 -0000
> > @@ -874,6 +874,9 @@
> > if (!newscreen)
> > return -ENOMEM;
> > 
> > +       if (vc = sel_cons)
> > +               clear_selection();
> > +
> > old_rows = vc->vc_rows;
> > old_row_size = vc->vc_size_row;
>
> This helped with the use-after-frees and out-of-bounds.
> Tested-by: Dmitry Vyukov <dvyukov@google.com>
>
> However, now the test program hanged in D unkillable stack on some
> kind of kernel deadlock. Don't know if it's induced by your patch, or
> just another bug. At least there are no vc_do_resize in stacks.
>
> # ps afxu | grep a.out
> root      6163  6.5  0.0      0     0 pts/0    Zl   13:25   0:00  |
>    \_ [a.out] <defunct>
>
> # ls /proc/6163/task/
> 6163  6191  6193  6194 6201
> 
> # cat /proc/6163/task/*/stack
> [<     inline     >] down_read_failed drivers/tty/tty_ldsem.c:241
> [<ffffffff831b8da6>] __ldsem_down_read_nested+0x2a6/0x5b0 drivers/tty/tty_ldsem.c:332
> [<ffffffff831b23f5>] tty_ldisc_ref_wait+0x35/0xb0 drivers/tty/tty_ldisc.c:274
> [<ffffffff831962b7>] tty_write+0x177/0x840 drivers/tty/tty_io.c:1250
> [<ffffffff8182c700>] __vfs_write+0x110/0x620 fs/read_write.c:510
> [<ffffffff8182dc05>] vfs_write+0x175/0x4e0 fs/read_write.c:560
> [<     inline     >] SYSC_write fs/read_write.c:607
> [<ffffffff818314c9>] SyS_write+0xd9/0x1b0 fs/read_write.c:599
> [<ffffffff86daf545>] entry_SYSCALL_64_fastpath+0x23/0xc6
> arch/x86/entry/entry_64.S:208

The patch below removes the resize ioctl's from the first test program. 
Are there any use-after-free/out-of-bounds errors when running the patched 
test program on the unpatched kernel? If not, but there are still 
deadlocks, then perhaps they aren't caused by the proposed kernel patch?

--- test.c
+++ test.c.new
@@ -141,8 +141,6 @@
     NONFAILING(*(uint16_t*)0x20f77ff9 = (uint16_t)0x6);
     NONFAILING(*(uint16_t*)0x20f77ffb = (uint16_t)0x3f);
     NONFAILING(*(uint16_t*)0x20f77ffd = (uint16_t)0x0);
-    r[17] = execute_syscall(__NR_ioctl, r[8], 0x541cul, 0x20f77ff4ul, 0,
-                            0, 0, 0, 0, 0);
     break;
   case 8:
     NONFAILING(*(uint32_t*)0x20f6dffc = (uint32_t)0x5);
@@ -212,8 +210,6 @@
     NONFAILING(*(uint16_t*)0x20f78ffa = (uint16_t)0xeb8);
     NONFAILING(*(uint16_t*)0x20f78ffc = (uint16_t)0x9);
     NONFAILING(*(uint16_t*)0x20f78ffe = (uint16_t)0x7);
-    r2[17] = execute_syscall(__NR_ioctl, r2[5], 0x5609ul, 0x20f78ffaul, 0,
-                            0, 0, 0, 0, 0);
     break;
   case 8:
     r2[18] @@ -273,8 +269,6 @@
     NONFAILING(*(uint16_t*)0x20f70002 = (uint16_t)0x2);
     NONFAILING(*(uint16_t*)0x20f70004 = (uint16_t)0xd1e);
     NONFAILING(*(uint16_t*)0x20f70006 = (uint16_t)0x7);
-    r2[34] = execute_syscall(__NR_ioctl, r2[5], 0x5414ul, 0x20f70000ul, 0,
-                            0, 0, 0, 0, 0);
     break;
   }
   return 0;


^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: tty, fbcon: use-after-free in fbcon_invert_region
  2016-10-11 22:48     ` Scot Doyle
@ 2016-10-13 11:08       ` Dmitry Vyukov
  -1 siblings, 0 replies; 14+ messages in thread
From: Dmitry Vyukov @ 2016-10-13 11:08 UTC (permalink / raw)
  To: Scot Doyle
  Cc: Greg Kroah-Hartman, Peter Hurley, Jiri Slaby, LKML, plagnioj,
	tomi.valkeinen, jean-philippe.brucker, linux-fbdev,
	Eric W. Biederman, syzkaller

On Wed, Oct 12, 2016 at 12:48 AM, Scot Doyle <lkml14@scotdoyle.com> wrote:
>> On Tue, Oct 11, 2016 at 3:43 AM, Scot Doyle <lkml14@scotdoyle.com> wrote:
>> > I wonder if the text selection is outside the newly resized vc?
>> > Does this patch help?
>> >
>> > --- vt.c        2016-10-11 00:32:43.079605599 -0000
>> > +++ vt.c.new    2016-10-11 00:36:12.744650759 -0000
>> > @@ -874,6 +874,9 @@
>> > if (!newscreen)
>> > return -ENOMEM;
>> >
>> > +       if (vc == sel_cons)
>> > +               clear_selection();
>> > +
>> > old_rows = vc->vc_rows;
>> > old_row_size = vc->vc_size_row;
>>
>> This helped with the use-after-frees and out-of-bounds.
>> Tested-by: Dmitry Vyukov <dvyukov@google.com>
>>
>> However, now the test program hanged in D unkillable stack on some
>> kind of kernel deadlock. Don't know if it's induced by your patch, or
>> just another bug. At least there are no vc_do_resize in stacks.
>>
>> # ps afxu | grep a.out
>> root      6163  6.5  0.0      0     0 pts/0    Zl   13:25   0:00  |
>>    \_ [a.out] <defunct>
>>
>> # ls /proc/6163/task/
>> 6163  6191  6193  6194 6201
>>
>> # cat /proc/6163/task/*/stack
>> [<     inline     >] down_read_failed drivers/tty/tty_ldsem.c:241
>> [<ffffffff831b8da6>] __ldsem_down_read_nested+0x2a6/0x5b0 drivers/tty/tty_ldsem.c:332
>> [<ffffffff831b23f5>] tty_ldisc_ref_wait+0x35/0xb0 drivers/tty/tty_ldisc.c:274
>> [<ffffffff831962b7>] tty_write+0x177/0x840 drivers/tty/tty_io.c:1250
>> [<ffffffff8182c700>] __vfs_write+0x110/0x620 fs/read_write.c:510
>> [<ffffffff8182dc05>] vfs_write+0x175/0x4e0 fs/read_write.c:560
>> [<     inline     >] SYSC_write fs/read_write.c:607
>> [<ffffffff818314c9>] SyS_write+0xd9/0x1b0 fs/read_write.c:599
>> [<ffffffff86daf545>] entry_SYSCALL_64_fastpath+0x23/0xc6
>> arch/x86/entry/entry_64.S:208
>
> The patch below removes the resize ioctl's from the first test program.
> Are there any use-after-free/out-of-bounds errors when running the patched
> test program on the unpatched kernel? If not, but there are still
> deadlocks, then perhaps they aren't caused by the proposed kernel patch?

Yes, I've removed these:

ioctl(0, 0x5609ul, 0);  // VT_RESIZE
ioctl(0, 0x5414ul, 0);  // TIOCSWINSZ

It does not crash, but still deadlocks. So I guess your patch fixes
the crashes. Please mail a patch with the fix.


> --- test.c
> +++ test.c.new
> @@ -141,8 +141,6 @@
>      NONFAILING(*(uint16_t*)0x20f77ff9 = (uint16_t)0x6);
>      NONFAILING(*(uint16_t*)0x20f77ffb = (uint16_t)0x3f);
>      NONFAILING(*(uint16_t*)0x20f77ffd = (uint16_t)0x0);
> -    r[17] = execute_syscall(__NR_ioctl, r[8], 0x541cul, 0x20f77ff4ul, 0,
> -                            0, 0, 0, 0, 0);
>      break;
>    case 8:
>      NONFAILING(*(uint32_t*)0x20f6dffc = (uint32_t)0x5);
> @@ -212,8 +210,6 @@
>      NONFAILING(*(uint16_t*)0x20f78ffa = (uint16_t)0xeb8);
>      NONFAILING(*(uint16_t*)0x20f78ffc = (uint16_t)0x9);
>      NONFAILING(*(uint16_t*)0x20f78ffe = (uint16_t)0x7);
> -    r2[17] = execute_syscall(__NR_ioctl, r2[5], 0x5609ul, 0x20f78ffaul, 0,
> -                            0, 0, 0, 0, 0);
>      break;
>    case 8:
>      r2[18] =
> @@ -273,8 +269,6 @@
>      NONFAILING(*(uint16_t*)0x20f70002 = (uint16_t)0x2);
>      NONFAILING(*(uint16_t*)0x20f70004 = (uint16_t)0xd1e);
>      NONFAILING(*(uint16_t*)0x20f70006 = (uint16_t)0x7);
> -    r2[34] = execute_syscall(__NR_ioctl, r2[5], 0x5414ul, 0x20f70000ul, 0,
> -                            0, 0, 0, 0, 0);
>      break;
>    }
>    return 0;
>

^ permalink raw reply	[flat|nested] 14+ messages in thread
* Re: tty, fbcon: use-after-free in fbcon_invert_region
@ 2016-10-13 11:08       ` Dmitry Vyukov
  0 siblings, 0 replies; 14+ messages in thread
From: Dmitry Vyukov @ 2016-10-13 11:08 UTC (permalink / raw)
  To: Scot Doyle
  Cc: Greg Kroah-Hartman, Peter Hurley, Jiri Slaby, LKML, plagnioj,
	tomi.valkeinen, jean-philippe.brucker, linux-fbdev,
	Eric W. Biederman, syzkaller

On Wed, Oct 12, 2016 at 12:48 AM, Scot Doyle <lkml14@scotdoyle.com> wrote:
>> On Tue, Oct 11, 2016 at 3:43 AM, Scot Doyle <lkml14@scotdoyle.com> wrote:
>> > I wonder if the text selection is outside the newly resized vc?
>> > Does this patch help?
>> >
>> > --- vt.c        2016-10-11 00:32:43.079605599 -0000
>> > +++ vt.c.new    2016-10-11 00:36:12.744650759 -0000
>> > @@ -874,6 +874,9 @@
>> > if (!newscreen)
>> > return -ENOMEM;
>> >
>> > +       if (vc = sel_cons)
>> > +               clear_selection();
>> > +
>> > old_rows = vc->vc_rows;
>> > old_row_size = vc->vc_size_row;
>>
>> This helped with the use-after-frees and out-of-bounds.
>> Tested-by: Dmitry Vyukov <dvyukov@google.com>
>>
>> However, now the test program hanged in D unkillable stack on some
>> kind of kernel deadlock. Don't know if it's induced by your patch, or
>> just another bug. At least there are no vc_do_resize in stacks.
>>
>> # ps afxu | grep a.out
>> root      6163  6.5  0.0      0     0 pts/0    Zl   13:25   0:00  |
>>    \_ [a.out] <defunct>
>>
>> # ls /proc/6163/task/
>> 6163  6191  6193  6194 6201
>>
>> # cat /proc/6163/task/*/stack
>> [<     inline     >] down_read_failed drivers/tty/tty_ldsem.c:241
>> [<ffffffff831b8da6>] __ldsem_down_read_nested+0x2a6/0x5b0 drivers/tty/tty_ldsem.c:332
>> [<ffffffff831b23f5>] tty_ldisc_ref_wait+0x35/0xb0 drivers/tty/tty_ldisc.c:274
>> [<ffffffff831962b7>] tty_write+0x177/0x840 drivers/tty/tty_io.c:1250
>> [<ffffffff8182c700>] __vfs_write+0x110/0x620 fs/read_write.c:510
>> [<ffffffff8182dc05>] vfs_write+0x175/0x4e0 fs/read_write.c:560
>> [<     inline     >] SYSC_write fs/read_write.c:607
>> [<ffffffff818314c9>] SyS_write+0xd9/0x1b0 fs/read_write.c:599
>> [<ffffffff86daf545>] entry_SYSCALL_64_fastpath+0x23/0xc6
>> arch/x86/entry/entry_64.S:208
>
> The patch below removes the resize ioctl's from the first test program.
> Are there any use-after-free/out-of-bounds errors when running the patched
> test program on the unpatched kernel? If not, but there are still
> deadlocks, then perhaps they aren't caused by the proposed kernel patch?

Yes, I've removed these:

ioctl(0, 0x5609ul, 0);  // VT_RESIZE
ioctl(0, 0x5414ul, 0);  // TIOCSWINSZ

It does not crash, but still deadlocks. So I guess your patch fixes
the crashes. Please mail a patch with the fix.


> --- test.c
> +++ test.c.new
> @@ -141,8 +141,6 @@
>      NONFAILING(*(uint16_t*)0x20f77ff9 = (uint16_t)0x6);
>      NONFAILING(*(uint16_t*)0x20f77ffb = (uint16_t)0x3f);
>      NONFAILING(*(uint16_t*)0x20f77ffd = (uint16_t)0x0);
> -    r[17] = execute_syscall(__NR_ioctl, r[8], 0x541cul, 0x20f77ff4ul, 0,
> -                            0, 0, 0, 0, 0);
>      break;
>    case 8:
>      NONFAILING(*(uint32_t*)0x20f6dffc = (uint32_t)0x5);
> @@ -212,8 +210,6 @@
>      NONFAILING(*(uint16_t*)0x20f78ffa = (uint16_t)0xeb8);
>      NONFAILING(*(uint16_t*)0x20f78ffc = (uint16_t)0x9);
>      NONFAILING(*(uint16_t*)0x20f78ffe = (uint16_t)0x7);
> -    r2[17] = execute_syscall(__NR_ioctl, r2[5], 0x5609ul, 0x20f78ffaul, 0,
> -                            0, 0, 0, 0, 0);
>      break;
>    case 8:
>      r2[18] > @@ -273,8 +269,6 @@
>      NONFAILING(*(uint16_t*)0x20f70002 = (uint16_t)0x2);
>      NONFAILING(*(uint16_t*)0x20f70004 = (uint16_t)0xd1e);
>      NONFAILING(*(uint16_t*)0x20f70006 = (uint16_t)0x7);
> -    r2[34] = execute_syscall(__NR_ioctl, r2[5], 0x5414ul, 0x20f70000ul, 0,
> -                            0, 0, 0, 0, 0);
>      break;
>    }
>    return 0;
>

^ permalink raw reply	[flat|nested] 14+ messages in thread
* [PATCH] vt: clear selection before resizing
  2016-10-13 11:08       ` Dmitry Vyukov
@ 2016-10-13 17:12         ` Scot Doyle
  -1 siblings, 0 replies; 14+ messages in thread
From: Scot Doyle @ 2016-10-13 17:12 UTC (permalink / raw)
  To: Greg Kroah-Hartman
  Cc: Jiri Slaby, Dmitry Vyukov, Peter Hurley, tomi.valkeinen,
	jean-philippe.brucker, Eric W. Biederman, linux-kernel,
	linux-fbdev

When resizing a vt its selection may exceed the new size, resulting in
an invalid memory access [1]. Clear the selection before resizing.

[1] http://lkml.kernel.org/r/CACT4Y+acDTwy4umEvf5ROBGiRJNrxHN4Cn5szCXE5Jw-d1B=Xw@mail.gmail.com

Reported-and-tested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Scot Doyle <lkml14@scotdoyle.com>
---
 drivers/tty/vt/vt.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 06fb39c..5d6a549 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -874,6 +874,9 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
 	if (!newscreen)
 		return -ENOMEM;
 
+	if (vc == sel_cons)
+		clear_selection();
+
 	old_rows = vc->vc_rows;
 	old_row_size = vc->vc_size_row;
 
-- 
2.7.4

^ permalink raw reply related	[flat|nested] 14+ messages in thread
* [PATCH] vt: clear selection before resizing
@ 2016-10-13 17:12         ` Scot Doyle
  0 siblings, 0 replies; 14+ messages in thread
From: Scot Doyle @ 2016-10-13 17:12 UTC (permalink / raw)
  To: Greg Kroah-Hartman
  Cc: Jiri Slaby, Dmitry Vyukov, Peter Hurley, tomi.valkeinen,
	jean-philippe.brucker, Eric W. Biederman, linux-kernel,
	linux-fbdev

When resizing a vt its selection may exceed the new size, resulting in
an invalid memory access [1]. Clear the selection before resizing.

[1] http://lkml.kernel.org/r/CACT4Y+acDTwy4umEvf5ROBGiRJNrxHN4Cn5szCXE5Jw-d1B=Xw@mail.gmail.com

Reported-and-tested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Scot Doyle <lkml14@scotdoyle.com>
---
 drivers/tty/vt/vt.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 06fb39c..5d6a549 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -874,6 +874,9 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
 	if (!newscreen)
 		return -ENOMEM;
 
+	if (vc = sel_cons)
+		clear_selection();
+
 	old_rows = vc->vc_rows;
 	old_row_size = vc->vc_size_row;
 
-- 
2.7.4


^ permalink raw reply related	[flat|nested] 14+ messages in thread
end of thread, other threads:[~2016-10-13 17:13 UTC | newest]

Thread overview: 14+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-09-03 19:20 tty, fbcon: use-after-free in fbcon_invert_region Dmitry Vyukov
2016-09-03 19:20 ` Dmitry Vyukov
2016-10-07 19:59 ` Dmitry Vyukov
2016-10-07 19:59   ` Dmitry Vyukov
2016-10-11  1:43   ` Scot Doyle
2016-10-11  1:43     ` Scot Doyle
2016-10-11 13:31     ` Dmitry Vyukov
2016-10-11 13:31       ` Dmitry Vyukov
2016-10-11 22:48   ` Scot Doyle
2016-10-11 22:48     ` Scot Doyle
2016-10-13 11:08     ` Dmitry Vyukov
2016-10-13 11:08       ` Dmitry Vyukov
2016-10-13 17:12       ` [PATCH] vt: clear selection before resizing Scot Doyle
2016-10-13 17:12         ` Scot Doyle

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