linux.git/sound/core/timer.c, branch v3.18.72 Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git ALSA: timer: Fix race between read and ioctl 2017-06-14T10:54:21+00:00 Takashi Iwai tiwai@suse.de 2017-06-02T13:03:38+00:00 d96c363ff004fbb42f728b3e4299a71c4e567568 commit d11662f4f798b50d8c8743f433842c3e40fe3378 upstream. The read from ALSA timer device, the function snd_timer_user_tread(), may access to an uninitialized struct snd_timer_user fields when the read is concurrently performed while the ioctl like snd_timer_user_tselect() is invoked. We have already fixed the races among ioctls via a mutex, but we seem to have forgotten the race between read vs ioctl. This patch simply applies (more exactly extends the already applied range of) tu->ioctl_lock in snd_timer_user_tread() for closing the race window. Reported-by: Alexander Potapenko <glider@google.com> Tested-by: Alexander Potapenko <glider@google.com> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit d11662f4f798b50d8c8743f433842c3e40fe3378 upstream.

The read from ALSA timer device, the function snd_timer_user_tread(),
may access to an uninitialized struct snd_timer_user fields when the
read is concurrently performed while the ioctl like
snd_timer_user_tselect() is invoked.  We have already fixed the races
among ioctls via a mutex, but we seem to have forgotten the race
between read vs ioctl.

This patch simply applies (more exactly extends the already applied
range of) tu->ioctl_lock in snd_timer_user_tread() for closing the
race window.

Reported-by: Alexander Potapenko <glider@google.com>
Tested-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ALSA: timer: Fix missing queue indices reset at SNDRV_TIMER_IOCTL_SELECT 2017-06-14T10:54:20+00:00 Takashi Iwai tiwai@suse.de 2017-06-02T15:26:56+00:00 69413811d2536f8ad626cc9537d34dd39133ebab commit ba3021b2c79b2fa9114f92790a99deb27a65b728 upstream. snd_timer_user_tselect() reallocates the queue buffer dynamically, but it forgot to reset its indices. Since the read may happen concurrently with ioctl and snd_timer_user_tselect() allocates the buffer via kmalloc(), this may lead to the leak of uninitialized kernel-space data, as spotted via KMSAN: BUG: KMSAN: use of unitialized memory in snd_timer_user_read+0x6c4/0xa10 CPU: 0 PID: 1037 Comm: probe Not tainted 4.11.0-rc5+ #2739 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:16 dump_stack+0x143/0x1b0 lib/dump_stack.c:52 kmsan_report+0x12a/0x180 mm/kmsan/kmsan.c:1007 kmsan_check_memory+0xc2/0x140 mm/kmsan/kmsan.c:1086 copy_to_user ./arch/x86/include/asm/uaccess.h:725 snd_timer_user_read+0x6c4/0xa10 sound/core/timer.c:2004 do_loop_readv_writev fs/read_write.c:716 __do_readv_writev+0x94c/0x1380 fs/read_write.c:864 do_readv_writev fs/read_write.c:894 vfs_readv fs/read_write.c:908 do_readv+0x52a/0x5d0 fs/read_write.c:934 SYSC_readv+0xb6/0xd0 fs/read_write.c:1021 SyS_readv+0x87/0xb0 fs/read_write.c:1018 This patch adds the missing reset of queue indices. Together with the previous fix for the ioctl/read race, we cover the whole problem. Reported-by: Alexander Potapenko <glider@google.com> Tested-by: Alexander Potapenko <glider@google.com> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit ba3021b2c79b2fa9114f92790a99deb27a65b728 upstream.

snd_timer_user_tselect() reallocates the queue buffer dynamically, but
it forgot to reset its indices.  Since the read may happen
concurrently with ioctl and snd_timer_user_tselect() allocates the
buffer via kmalloc(), this may lead to the leak of uninitialized
kernel-space data, as spotted via KMSAN:

  BUG: KMSAN: use of unitialized memory in snd_timer_user_read+0x6c4/0xa10
  CPU: 0 PID: 1037 Comm: probe Not tainted 4.11.0-rc5+ #2739
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
  Call Trace:
   __dump_stack lib/dump_stack.c:16
   dump_stack+0x143/0x1b0 lib/dump_stack.c:52
   kmsan_report+0x12a/0x180 mm/kmsan/kmsan.c:1007
   kmsan_check_memory+0xc2/0x140 mm/kmsan/kmsan.c:1086
   copy_to_user ./arch/x86/include/asm/uaccess.h:725
   snd_timer_user_read+0x6c4/0xa10 sound/core/timer.c:2004
   do_loop_readv_writev fs/read_write.c:716
   __do_readv_writev+0x94c/0x1380 fs/read_write.c:864
   do_readv_writev fs/read_write.c:894
   vfs_readv fs/read_write.c:908
   do_readv+0x52a/0x5d0 fs/read_write.c:934
   SYSC_readv+0xb6/0xd0 fs/read_write.c:1021
   SyS_readv+0x87/0xb0 fs/read_write.c:1018

This patch adds the missing reset of queue indices.  Together with the
previous fix for the ioctl/read race, we cover the whole problem.

Reported-by: Alexander Potapenko <glider@google.com>
Tested-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ALSA: timer: Fix leak in events via snd_timer_user_tinterrupt 2017-05-20T12:18:45+00:00 Kangjie Lu kangjielu@gmail.com 2016-05-03T20:44:32+00:00 7c1e076eefe76f1522ce94a4d7ce63e42b14438f commit e4ec8cc8039a7063e24204299b462bd1383184a5 upstream. The stack object “r1” has a total size of 32 bytes. Its field “event” and “val” both contain 4 bytes padding. These 8 bytes padding bytes are sent to user without being initialized. Signed-off-by: Kangjie Lu <kjlu@gatech.edu> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Amit Pundir <amit.pundir@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit e4ec8cc8039a7063e24204299b462bd1383184a5 upstream.

The stack object “r1” has a total size of 32 bytes. Its field
“event” and “val” both contain 4 bytes padding. These 8 bytes
padding bytes are sent to user without being initialized.

Signed-off-by: Kangjie Lu <kjlu@gatech.edu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ALSA: timer: Fix leak in events via snd_timer_user_ccallback 2017-05-20T12:18:45+00:00 Kangjie Lu kangjielu@gmail.com 2016-05-03T20:44:20+00:00 bbb79774fcea8b92df051d1d68fcba18d884f860 commit 9a47e9cff994f37f7f0dbd9ae23740d0f64f9fe6 upstream. The stack object “r1” has a total size of 32 bytes. Its field “event” and “val” both contain 4 bytes padding. These 8 bytes padding bytes are sent to user without being initialized. Signed-off-by: Kangjie Lu <kjlu@gatech.edu> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Amit Pundir <amit.pundir@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 9a47e9cff994f37f7f0dbd9ae23740d0f64f9fe6 upstream.

The stack object “r1” has a total size of 32 bytes. Its field
“event” and “val” both contain 4 bytes padding. These 8 bytes
padding bytes are sent to user without being initialized.

Signed-off-by: Kangjie Lu <kjlu@gatech.edu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ALSA: timer: Fix leak in SNDRV_TIMER_IOCTL_PARAMS 2017-05-20T12:18:45+00:00 Kangjie Lu kangjielu@gmail.com 2016-05-03T20:44:07+00:00 bbcf19d306745832e043e02c7b3d4f4fad82d61e commit cec8f96e49d9be372fdb0c3836dcf31ec71e457e upstream. The stack object “tread” has a total size of 32 bytes. Its field “event” and “val” both contain 4 bytes padding. These 8 bytes padding bytes are sent to user without being initialized. Signed-off-by: Kangjie Lu <kjlu@gatech.edu> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Amit Pundir <amit.pundir@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit cec8f96e49d9be372fdb0c3836dcf31ec71e457e upstream.

The stack object “tread” has a total size of 32 bytes. Its field
“event” and “val” both contain 4 bytes padding. These 8 bytes
padding bytes are sent to user without being initialized.

Signed-off-by: Kangjie Lu <kjlu@gatech.edu>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ALSA: timer: Fix race among timer ioctls 2017-05-20T12:18:45+00:00 Takashi Iwai tiwai@suse.de 2016-01-13T16:48:01+00:00 19f609798f7ea6392028091b42dd53b3c7f9368f commit af368027a49a751d6ff4ee9e3f9961f35bb4fede upstream. ALSA timer ioctls have an open race and this may lead to a use-after-free of timer instance object. A simplistic fix is to make each ioctl exclusive. We have already tread_sem for controlling the tread, and extend this as a global mutex to be applied to each ioctl. The downside is, of course, the worse concurrency. But these ioctls aren't to be parallel accessible, in anyway, so it should be fine to serialize there. Reported-by: Dmitry Vyukov <dvyukov@google.com> Tested-by: Dmitry Vyukov <dvyukov@google.com> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Amit Pundir <amit.pundir@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit af368027a49a751d6ff4ee9e3f9961f35bb4fede upstream.

ALSA timer ioctls have an open race and this may lead to a
use-after-free of timer instance object.  A simplistic fix is to make
each ioctl exclusive.  We have already tread_sem for controlling the
tread, and extend this as a global mutex to be applied to each ioctl.

The downside is, of course, the worse concurrency.  But these ioctls
aren't to be parallel accessible, in anyway, so it should be fine to
serialize there.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Amit Pundir <amit.pundir@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ALSA: timer: Fix zero-division by continue of uninitialized instance 2016-10-06T02:40:20+00:00 Takashi Iwai tiwai@suse.de 2016-09-07T13:45:31+00:00 1a30ab34ce72bcf8b549c72d9c7e64ace95f02b3 [ Upstream commit 9f8a7658bcafb2a7853f7a2eae8a94e87e6e695b ] When a user timer instance is continued without the explicit start beforehand, the system gets eventually zero-division error like: divide error: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN CPU: 1 PID: 27320 Comm: syz-executor Not tainted 4.8.0-rc3-next-20160825+ #8 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 task: ffff88003c9b2280 task.stack: ffff880027280000 RIP: 0010:[<ffffffff858e1a6c>] [< inline >] ktime_divns include/linux/ktime.h:195 RIP: 0010:[<ffffffff858e1a6c>] [<ffffffff858e1a6c>] snd_hrtimer_callback+0x1bc/0x3c0 sound/core/hrtimer.c:62 Call Trace: <IRQ> [< inline >] __run_hrtimer kernel/time/hrtimer.c:1238 [<ffffffff81504335>] __hrtimer_run_queues+0x325/0xe70 kernel/time/hrtimer.c:1302 [<ffffffff81506ceb>] hrtimer_interrupt+0x18b/0x420 kernel/time/hrtimer.c:1336 [<ffffffff8126d8df>] local_apic_timer_interrupt+0x6f/0xe0 arch/x86/kernel/apic/apic.c:933 [<ffffffff86e13056>] smp_apic_timer_interrupt+0x76/0xa0 arch/x86/kernel/apic/apic.c:957 [<ffffffff86e1210c>] apic_timer_interrupt+0x8c/0xa0 arch/x86/entry/entry_64.S:487 <EOI> ..... Although a similar issue was spotted and a fix patch was merged in commit [6b760bb2c63a: ALSA: timer: fix division by zero after SNDRV_TIMER_IOCTL_CONTINUE], it seems covering only a part of iceberg. In this patch, we fix the issue a bit more drastically. Basically the continue of an uninitialized timer is supposed to be a fresh start, so we do it for user timers. For the direct snd_timer_continue() call, there is no way to pass the initial tick value, so we kick out for the uninitialized case. Reported-by: Dmitry Vyukov <dvyukov@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> 
[ Upstream commit 9f8a7658bcafb2a7853f7a2eae8a94e87e6e695b ]

When a user timer instance is continued without the explicit start
beforehand, the system gets eventually zero-division error like:

  divide error: 0000 [#1] SMP DEBUG_PAGEALLOC KASAN
  CPU: 1 PID: 27320 Comm: syz-executor Not tainted 4.8.0-rc3-next-20160825+ #8
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
   task: ffff88003c9b2280 task.stack: ffff880027280000
   RIP: 0010:[<ffffffff858e1a6c>]  [<     inline     >] ktime_divns include/linux/ktime.h:195
   RIP: 0010:[<ffffffff858e1a6c>]  [<ffffffff858e1a6c>] snd_hrtimer_callback+0x1bc/0x3c0 sound/core/hrtimer.c:62
  Call Trace:
   <IRQ>
   [<     inline     >] __run_hrtimer kernel/time/hrtimer.c:1238
   [<ffffffff81504335>] __hrtimer_run_queues+0x325/0xe70 kernel/time/hrtimer.c:1302
   [<ffffffff81506ceb>] hrtimer_interrupt+0x18b/0x420 kernel/time/hrtimer.c:1336
   [<ffffffff8126d8df>] local_apic_timer_interrupt+0x6f/0xe0 arch/x86/kernel/apic/apic.c:933
   [<ffffffff86e13056>] smp_apic_timer_interrupt+0x76/0xa0 arch/x86/kernel/apic/apic.c:957
   [<ffffffff86e1210c>] apic_timer_interrupt+0x8c/0xa0 arch/x86/entry/entry_64.S:487
   <EOI>
   .....

Although a similar issue was spotted and a fix patch was merged in
commit [6b760bb2c63a: ALSA: timer: fix division by zero after
SNDRV_TIMER_IOCTL_CONTINUE], it seems covering only a part of
iceberg.

In this patch, we fix the issue a bit more drastically.  Basically the
continue of an uninitialized timer is supposed to be a fresh start, so
we do it for user timers.  For the direct snd_timer_continue() call,
there is no way to pass the initial tick value, so we kick out for the
uninitialized case.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
ALSA: timer: Call notifier in the same spinlock 2016-10-06T02:40:20+00:00 Takashi Iwai tiwai@suse.de 2016-02-10T11:47:03+00:00 1174014a57eda377f5ed60e4c880c935d02c7bde [ Upstream commit f65e0d299807d8a11812845c972493c3f9a18e10 ] snd_timer_notify1() is called outside the spinlock and it retakes the lock after the unlock. This is rather racy, and it's safer to move snd_timer_notify() call inside the main spinlock. The patch also contains a slight refactoring / cleanup of the code. Now all start/stop/continue/pause look more symmetric and a bit better readable. Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> 
[ Upstream commit f65e0d299807d8a11812845c972493c3f9a18e10 ]

snd_timer_notify1() is called outside the spinlock and it retakes the
lock after the unlock.  This is rather racy, and it's safer to move
snd_timer_notify() call inside the main spinlock.

The patch also contains a slight refactoring / cleanup of the code.
Now all start/stop/continue/pause look more symmetric and a bit better
readable.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
ALSA: timer: fix NULL pointer dereference on memory allocation failure 2016-10-04T04:53:55+00:00 Vegard Nossum vegard.nossum@oracle.com 2016-08-28T22:33:51+00:00 14e3a78605126470ca818bcdc0f2e922fd6bb3c2 [ Upstream commit 8ddc05638ee42b18ba4fe99b5fb647fa3ad20456 ] I hit this with syzkaller: kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 1327 Comm: a.out Not tainted 4.8.0-rc2+ #190 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 task: ffff88011278d600 task.stack: ffff8801120c0000 RIP: 0010:[<ffffffff82c8ba07>] [<ffffffff82c8ba07>] snd_hrtimer_start+0x77/0x100 RSP: 0018:ffff8801120c7a60 EFLAGS: 00010006 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000007 RDX: 0000000000000009 RSI: 1ffff10023483091 RDI: 0000000000000048 RBP: ffff8801120c7a78 R08: ffff88011a5cf768 R09: ffff88011a5ba790 R10: 0000000000000002 R11: ffffed00234b9ef1 R12: ffff880114843980 R13: ffffffff84213c00 R14: ffff880114843ab0 R15: 0000000000000286 FS: 00007f72958f3700(0000) GS:ffff88011aa00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000603001 CR3: 00000001126ab000 CR4: 00000000000006f0 Stack: ffff880114843980 ffff880111eb2dc0 ffff880114843a34 ffff8801120c7ad0 ffffffff82c81ab1 0000000000000000 ffffffff842138e0 0000000100000000 ffff880111eb2dd0 ffff880111eb2dc0 0000000000000001 ffff880111eb2dc0 Call Trace: [<ffffffff82c81ab1>] snd_timer_start1+0x331/0x670 [<ffffffff82c85bfd>] snd_timer_start+0x5d/0xa0 [<ffffffff82c8795e>] snd_timer_user_ioctl+0x88e/0x2830 [<ffffffff8159f3a0>] ? __follow_pte.isra.49+0x430/0x430 [<ffffffff82c870d0>] ? snd_timer_pause+0x80/0x80 [<ffffffff815a26fa>] ? do_wp_page+0x3aa/0x1c90 [<ffffffff8132762f>] ? put_prev_entity+0x108f/0x21a0 [<ffffffff82c870d0>] ? snd_timer_pause+0x80/0x80 [<ffffffff816b0733>] do_vfs_ioctl+0x193/0x1050 [<ffffffff813510af>] ? cpuacct_account_field+0x12f/0x1a0 [<ffffffff816b05a0>] ? ioctl_preallocate+0x200/0x200 [<ffffffff81002f2f>] ? syscall_trace_enter+0x3cf/0xdb0 [<ffffffff815045ba>] ? __context_tracking_exit.part.4+0x9a/0x1e0 [<ffffffff81002b60>] ? exit_to_usermode_loop+0x190/0x190 [<ffffffff82001a97>] ? check_preemption_disabled+0x37/0x1e0 [<ffffffff81d93889>] ? security_file_ioctl+0x89/0xb0 [<ffffffff816b167f>] SyS_ioctl+0x8f/0xc0 [<ffffffff816b15f0>] ? do_vfs_ioctl+0x1050/0x1050 [<ffffffff81005524>] do_syscall_64+0x1c4/0x4e0 [<ffffffff83c32b2a>] entry_SYSCALL64_slow_path+0x25/0x25 Code: c7 c7 c4 b9 c8 82 48 89 d9 4c 89 ee e8 63 88 7f fe e8 7e 46 7b fe 48 8d 7b 48 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 04 84 c0 7e 65 80 7b 48 00 74 0e e8 52 46 RIP [<ffffffff82c8ba07>] snd_hrtimer_start+0x77/0x100 RSP <ffff8801120c7a60> ---[ end trace 5955b08db7f2b029 ]--- This can happen if snd_hrtimer_open() fails to allocate memory and returns an error, which is currently not checked by snd_timer_open(): ioctl(SNDRV_TIMER_IOCTL_SELECT) - snd_timer_user_tselect() - snd_timer_close() - snd_hrtimer_close() - (struct snd_timer *) t->private_data = NULL - snd_timer_open() - snd_hrtimer_open() - kzalloc() fails; t->private_data is still NULL ioctl(SNDRV_TIMER_IOCTL_START) - snd_timer_user_start() - snd_timer_start() - snd_timer_start1() - snd_hrtimer_start() - t->private_data == NULL // boom Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> 
[ Upstream commit 8ddc05638ee42b18ba4fe99b5fb647fa3ad20456 ]

I hit this with syzkaller:

    kasan: CONFIG_KASAN_INLINE enabled
    kasan: GPF could be caused by NULL-ptr deref or user memory access
    general protection fault: 0000 [#1] PREEMPT SMP KASAN
    CPU: 0 PID: 1327 Comm: a.out Not tainted 4.8.0-rc2+ #190
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014
    task: ffff88011278d600 task.stack: ffff8801120c0000
    RIP: 0010:[<ffffffff82c8ba07>]  [<ffffffff82c8ba07>] snd_hrtimer_start+0x77/0x100
    RSP: 0018:ffff8801120c7a60  EFLAGS: 00010006
    RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000007
    RDX: 0000000000000009 RSI: 1ffff10023483091 RDI: 0000000000000048
    RBP: ffff8801120c7a78 R08: ffff88011a5cf768 R09: ffff88011a5ba790
    R10: 0000000000000002 R11: ffffed00234b9ef1 R12: ffff880114843980
    R13: ffffffff84213c00 R14: ffff880114843ab0 R15: 0000000000000286
    FS:  00007f72958f3700(0000) GS:ffff88011aa00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 0000000000603001 CR3: 00000001126ab000 CR4: 00000000000006f0
    Stack:
     ffff880114843980 ffff880111eb2dc0 ffff880114843a34 ffff8801120c7ad0
     ffffffff82c81ab1 0000000000000000 ffffffff842138e0 0000000100000000
     ffff880111eb2dd0 ffff880111eb2dc0 0000000000000001 ffff880111eb2dc0
    Call Trace:
     [<ffffffff82c81ab1>] snd_timer_start1+0x331/0x670
     [<ffffffff82c85bfd>] snd_timer_start+0x5d/0xa0
     [<ffffffff82c8795e>] snd_timer_user_ioctl+0x88e/0x2830
     [<ffffffff8159f3a0>] ? __follow_pte.isra.49+0x430/0x430
     [<ffffffff82c870d0>] ? snd_timer_pause+0x80/0x80
     [<ffffffff815a26fa>] ? do_wp_page+0x3aa/0x1c90
     [<ffffffff8132762f>] ? put_prev_entity+0x108f/0x21a0
     [<ffffffff82c870d0>] ? snd_timer_pause+0x80/0x80
     [<ffffffff816b0733>] do_vfs_ioctl+0x193/0x1050
     [<ffffffff813510af>] ? cpuacct_account_field+0x12f/0x1a0
     [<ffffffff816b05a0>] ? ioctl_preallocate+0x200/0x200
     [<ffffffff81002f2f>] ? syscall_trace_enter+0x3cf/0xdb0
     [<ffffffff815045ba>] ? __context_tracking_exit.part.4+0x9a/0x1e0
     [<ffffffff81002b60>] ? exit_to_usermode_loop+0x190/0x190
     [<ffffffff82001a97>] ? check_preemption_disabled+0x37/0x1e0
     [<ffffffff81d93889>] ? security_file_ioctl+0x89/0xb0
     [<ffffffff816b167f>] SyS_ioctl+0x8f/0xc0
     [<ffffffff816b15f0>] ? do_vfs_ioctl+0x1050/0x1050
     [<ffffffff81005524>] do_syscall_64+0x1c4/0x4e0
     [<ffffffff83c32b2a>] entry_SYSCALL64_slow_path+0x25/0x25
    Code: c7 c7 c4 b9 c8 82 48 89 d9 4c 89 ee e8 63 88 7f fe e8 7e 46 7b fe 48 8d 7b 48 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 04 84 c0 7e 65 80 7b 48 00 74 0e e8 52 46
    RIP  [<ffffffff82c8ba07>] snd_hrtimer_start+0x77/0x100
     RSP <ffff8801120c7a60>
    ---[ end trace 5955b08db7f2b029 ]---

This can happen if snd_hrtimer_open() fails to allocate memory and
returns an error, which is currently not checked by snd_timer_open():

    ioctl(SNDRV_TIMER_IOCTL_SELECT)
     - snd_timer_user_tselect()
	- snd_timer_close()
	   - snd_hrtimer_close()
	      - (struct snd_timer *) t->private_data = NULL
        - snd_timer_open()
           - snd_hrtimer_open()
              - kzalloc() fails; t->private_data is still NULL

    ioctl(SNDRV_TIMER_IOCTL_START)
     - snd_timer_user_start()
	- snd_timer_start()
	   - snd_timer_start1()
	      - snd_hrtimer_start()
		- t->private_data == NULL // boom

Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
ALSA: timer: fix division by zero after SNDRV_TIMER_IOCTL_CONTINUE 2016-10-04T04:53:50+00:00 Vegard Nossum vegard.nossum@oracle.com 2016-08-28T22:33:50+00:00 a987c6258df6763cedd736673aa11bfdf682f299 [ Upstream commit 6b760bb2c63a9e322c0e4a0b5daf335ad93d5a33 ] I got this: divide error: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 1327 Comm: a.out Not tainted 4.8.0-rc2+ #189 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 task: ffff8801120a9580 task.stack: ffff8801120b0000 RIP: 0010:[<ffffffff82c8bd9a>] [<ffffffff82c8bd9a>] snd_hrtimer_callback+0x1da/0x3f0 RSP: 0018:ffff88011aa87da8 EFLAGS: 00010006 RAX: 0000000000004f76 RBX: ffff880112655e88 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffff880112655ea0 RDI: 0000000000000001 RBP: ffff88011aa87e00 R08: ffff88013fff905c R09: ffff88013fff9048 R10: ffff88013fff9050 R11: 00000001050a7b8c R12: ffff880114778a00 R13: ffff880114778ab4 R14: ffff880114778b30 R15: 0000000000000000 FS: 00007f071647c700(0000) GS:ffff88011aa80000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000603001 CR3: 0000000112021000 CR4: 00000000000006e0 Stack: 0000000000000000 ffff880114778ab8 ffff880112655ea0 0000000000004f76 ffff880112655ec8 ffff880112655e80 ffff880112655e88 ffff88011aa98fc0 00000000b97ccf2b dffffc0000000000 ffff88011aa98fc0 ffff88011aa87ef0 Call Trace: <IRQ> [<ffffffff813abce7>] __hrtimer_run_queues+0x347/0xa00 [<ffffffff82c8bbc0>] ? snd_hrtimer_close+0x130/0x130 [<ffffffff813ab9a0>] ? retrigger_next_event+0x1b0/0x1b0 [<ffffffff813ae1a6>] ? hrtimer_interrupt+0x136/0x4b0 [<ffffffff813ae220>] hrtimer_interrupt+0x1b0/0x4b0 [<ffffffff8120f91e>] local_apic_timer_interrupt+0x6e/0xf0 [<ffffffff81227ad3>] ? kvm_guest_apic_eoi_write+0x13/0xc0 [<ffffffff83c35086>] smp_apic_timer_interrupt+0x76/0xa0 [<ffffffff83c3416c>] apic_timer_interrupt+0x8c/0xa0 <EOI> [<ffffffff83c3239c>] ? _raw_spin_unlock_irqrestore+0x2c/0x60 [<ffffffff82c8185d>] snd_timer_start1+0xdd/0x670 [<ffffffff82c87015>] snd_timer_continue+0x45/0x80 [<ffffffff82c88100>] snd_timer_user_ioctl+0x1030/0x2830 [<ffffffff8159f3a0>] ? __follow_pte.isra.49+0x430/0x430 [<ffffffff82c870d0>] ? snd_timer_pause+0x80/0x80 [<ffffffff815a26fa>] ? do_wp_page+0x3aa/0x1c90 [<ffffffff815aa4f8>] ? handle_mm_fault+0xbc8/0x27f0 [<ffffffff815a9930>] ? __pmd_alloc+0x370/0x370 [<ffffffff82c870d0>] ? snd_timer_pause+0x80/0x80 [<ffffffff816b0733>] do_vfs_ioctl+0x193/0x1050 [<ffffffff816b05a0>] ? ioctl_preallocate+0x200/0x200 [<ffffffff81002f2f>] ? syscall_trace_enter+0x3cf/0xdb0 [<ffffffff815045ba>] ? __context_tracking_exit.part.4+0x9a/0x1e0 [<ffffffff81002b60>] ? exit_to_usermode_loop+0x190/0x190 [<ffffffff82001a97>] ? check_preemption_disabled+0x37/0x1e0 [<ffffffff81d93889>] ? security_file_ioctl+0x89/0xb0 [<ffffffff816b167f>] SyS_ioctl+0x8f/0xc0 [<ffffffff816b15f0>] ? do_vfs_ioctl+0x1050/0x1050 [<ffffffff81005524>] do_syscall_64+0x1c4/0x4e0 [<ffffffff83c32b2a>] entry_SYSCALL64_slow_path+0x25/0x25 Code: e8 fc 42 7b fe 8b 0d 06 8a 50 03 49 0f af cf 48 85 c9 0f 88 7c 01 00 00 48 89 4d a8 e8 e0 42 7b fe 48 8b 45 c0 48 8b 4d a8 48 99 <48> f7 f9 49 01 c7 e8 cb 42 7b fe 48 8b 55 d0 48 b8 00 00 00 00 RIP [<ffffffff82c8bd9a>] snd_hrtimer_callback+0x1da/0x3f0 RSP <ffff88011aa87da8> ---[ end trace 6aa380f756a21074 ]--- The problem happens when you call ioctl(SNDRV_TIMER_IOCTL_CONTINUE) on a completely new/unused timer -- it will have ->sticks == 0, which causes a divide by 0 in snd_hrtimer_callback(). Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Sasha Levin <alexander.levin@verizon.com> 
[ Upstream commit 6b760bb2c63a9e322c0e4a0b5daf335ad93d5a33 ]

I got this:

    divide error: 0000 [#1] PREEMPT SMP KASAN
    CPU: 1 PID: 1327 Comm: a.out Not tainted 4.8.0-rc2+ #189
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014
    task: ffff8801120a9580 task.stack: ffff8801120b0000
    RIP: 0010:[<ffffffff82c8bd9a>]  [<ffffffff82c8bd9a>] snd_hrtimer_callback+0x1da/0x3f0
    RSP: 0018:ffff88011aa87da8  EFLAGS: 00010006
    RAX: 0000000000004f76 RBX: ffff880112655e88 RCX: 0000000000000000
    RDX: 0000000000000000 RSI: ffff880112655ea0 RDI: 0000000000000001
    RBP: ffff88011aa87e00 R08: ffff88013fff905c R09: ffff88013fff9048
    R10: ffff88013fff9050 R11: 00000001050a7b8c R12: ffff880114778a00
    R13: ffff880114778ab4 R14: ffff880114778b30 R15: 0000000000000000
    FS:  00007f071647c700(0000) GS:ffff88011aa80000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 0000000000603001 CR3: 0000000112021000 CR4: 00000000000006e0
    Stack:
     0000000000000000 ffff880114778ab8 ffff880112655ea0 0000000000004f76
     ffff880112655ec8 ffff880112655e80 ffff880112655e88 ffff88011aa98fc0
     00000000b97ccf2b dffffc0000000000 ffff88011aa98fc0 ffff88011aa87ef0
    Call Trace:
     <IRQ>
     [<ffffffff813abce7>] __hrtimer_run_queues+0x347/0xa00
     [<ffffffff82c8bbc0>] ? snd_hrtimer_close+0x130/0x130
     [<ffffffff813ab9a0>] ? retrigger_next_event+0x1b0/0x1b0
     [<ffffffff813ae1a6>] ? hrtimer_interrupt+0x136/0x4b0
     [<ffffffff813ae220>] hrtimer_interrupt+0x1b0/0x4b0
     [<ffffffff8120f91e>] local_apic_timer_interrupt+0x6e/0xf0
     [<ffffffff81227ad3>] ? kvm_guest_apic_eoi_write+0x13/0xc0
     [<ffffffff83c35086>] smp_apic_timer_interrupt+0x76/0xa0
     [<ffffffff83c3416c>] apic_timer_interrupt+0x8c/0xa0
     <EOI>
     [<ffffffff83c3239c>] ? _raw_spin_unlock_irqrestore+0x2c/0x60
     [<ffffffff82c8185d>] snd_timer_start1+0xdd/0x670
     [<ffffffff82c87015>] snd_timer_continue+0x45/0x80
     [<ffffffff82c88100>] snd_timer_user_ioctl+0x1030/0x2830
     [<ffffffff8159f3a0>] ? __follow_pte.isra.49+0x430/0x430
     [<ffffffff82c870d0>] ? snd_timer_pause+0x80/0x80
     [<ffffffff815a26fa>] ? do_wp_page+0x3aa/0x1c90
     [<ffffffff815aa4f8>] ? handle_mm_fault+0xbc8/0x27f0
     [<ffffffff815a9930>] ? __pmd_alloc+0x370/0x370
     [<ffffffff82c870d0>] ? snd_timer_pause+0x80/0x80
     [<ffffffff816b0733>] do_vfs_ioctl+0x193/0x1050
     [<ffffffff816b05a0>] ? ioctl_preallocate+0x200/0x200
     [<ffffffff81002f2f>] ? syscall_trace_enter+0x3cf/0xdb0
     [<ffffffff815045ba>] ? __context_tracking_exit.part.4+0x9a/0x1e0
     [<ffffffff81002b60>] ? exit_to_usermode_loop+0x190/0x190
     [<ffffffff82001a97>] ? check_preemption_disabled+0x37/0x1e0
     [<ffffffff81d93889>] ? security_file_ioctl+0x89/0xb0
     [<ffffffff816b167f>] SyS_ioctl+0x8f/0xc0
     [<ffffffff816b15f0>] ? do_vfs_ioctl+0x1050/0x1050
     [<ffffffff81005524>] do_syscall_64+0x1c4/0x4e0
     [<ffffffff83c32b2a>] entry_SYSCALL64_slow_path+0x25/0x25
    Code: e8 fc 42 7b fe 8b 0d 06 8a 50 03 49 0f af cf 48 85 c9 0f 88 7c 01 00 00 48 89 4d a8 e8 e0 42 7b fe 48 8b 45 c0 48 8b 4d a8 48 99 <48> f7 f9 49 01 c7 e8 cb 42 7b fe 48 8b 55 d0 48 b8 00 00 00 00
    RIP  [<ffffffff82c8bd9a>] snd_hrtimer_callback+0x1da/0x3f0
     RSP <ffff88011aa87da8>
    ---[ end trace 6aa380f756a21074 ]---

The problem happens when you call ioctl(SNDRV_TIMER_IOCTL_CONTINUE) on a
completely new/unused timer -- it will have ->sticks == 0, which causes a
divide by 0 in snd_hrtimer_callback().

Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>