In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly. This adds a pointer back to struct
snd_timer.
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Add a jump target so that a bit of exception handling can be better reused
at the end of this function.

This issue was detected by using the Coccinelle software.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

The script "checkpatch.pl" pointed information out like the following.

ERROR: do not use assignment in if condition

Thus fix the affected source code place.
Signed-off-by: NMarkus Elfring <elfring@users.sourceforge.net>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Rename:

	wait_queue_t		=>	wait_queue_entry_t

'wait_queue_t' was always a slight misnomer: its name implies that it's a "queue",
but in reality it's a queue *entry*. The 'real' queue is the wait queue head,
which had to carry the name.

Start sorting this out by renaming it to 'wait_queue_entry_t'.

This also allows the real structure name 'struct __wait_queue' to
lose its double underscore and become 'struct wait_queue_entry',
which is the more canonical nomenclature for such data types.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

Just a tidy up to follow the standard EXPORT_SYMBOL*() declarations
in order to improve grep-ability.

- Move EXPORT_SYMBOL*() to the position right after its definition
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

For accessing the snd_timer_user queue indices, we take tu->qlock.
But it's forgotten in a couple of places.

The one in snd_timer_user_params() should be safe without the
spinlock as the timer is already stopped.  But it's better for
consistency.

The one in poll is just a read-out, so it's not inevitably needed, but
it'd be good to make the result consistent, too.
Tested-by: NAlexander Potapenko <glider@google.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

ALSA timer may reallocate the user queue upon request, and it happens
at three places for now: at opening, at SNDRV_TIMER_IOCTL_PARAMS, and
at SNDRV_TIMER_IOCTL_SELECT.  However, the last one,
snd_timer_user_tselect(), doesn't need to reallocate the buffer since
it doesn't change the queue size.  It does just because tu->tread
might have been changed before starting the timer.

Instead of *_SELECT ioctl, we should reallocate the queue at
SNDRV_TIMER_IOCTL_TREAD; then the timer is guaranteed to be stopped,
thus we can reassign the buffer more safely.

This patch implements that with a slight code refactoring.
Essentially, the patch achieves:
- Introduce realloc_user_queue() for (re-)allocating the ring buffer,
  and call it from all places.  Also, realloc_user_queue() uses
  kcalloc() for avoiding possible leaks.
- Add the buffer reallocation at SNDRV_TIMER_IOCTL_TREAD.  When it
  fails, tu->tread is restored to the old value, too.
- Drop the buffer reallocation at snd_timer_user_tselect().
Tested-by: NAlexander Potapenko <glider@google.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

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: NAlexander Potapenko <glider@google.com>
Tested-by: NAlexander Potapenko <glider@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

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: NAlexander Potapenko <glider@google.com>
Tested-by: NAlexander Potapenko <glider@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

The "r1" struct has memory holes.  We clear it with memset on one path
where it is used but not the other.  Let's just memset it at the start
of the function so it's always safe.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

We just checked "id.card < 0" on the lines before so we know it's not
true here.  We can delete that check.

Also checkpatch.pl complains about some extra curly braces so we may as
well fix that while we're at it.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched.h> into <linux/sched/signal.h>

Fix up affected files that include this signal functionality via sched.h.
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NIngo Molnar <mingo@kernel.org>

When a user sets a too small ticks with a fine-grained timer like
hrtimer, the kernel tries to fire up the timer irq too frequently.
This may lead to the condensed locks, eventually the kernel spinlock
lockup with warnings.

For avoiding such a situation, we define a lower limit of the
resolution, namely 1ms.  When the user passes a too small tick value
that results in less than that, the kernel returns -EINVAL now.
Reported-by: NDmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

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 [6b760bb2: 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: NDmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

I got this with syzkaller:

    ==================================================================
    BUG: KASAN: null-ptr-deref on address 0000000000000020
    Read of size 32 by task syz-executor/22519
    CPU: 1 PID: 22519 Comm: syz-executor Not tainted 4.8.0-rc2+ #169
    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2
    014
     0000000000000001 ffff880111a17a00 ffffffff81f9f141 ffff880111a17a90
     ffff880111a17c50 ffff880114584a58 ffff880114584a10 ffff880111a17a80
     ffffffff8161fe3f ffff880100000000 ffff880118d74a48 ffff880118d74a68
    Call Trace:
     [<ffffffff81f9f141>] dump_stack+0x83/0xb2
     [<ffffffff8161fe3f>] kasan_report_error+0x41f/0x4c0
     [<ffffffff8161ff74>] kasan_report+0x34/0x40
     [<ffffffff82c84b54>] ? snd_timer_user_read+0x554/0x790
     [<ffffffff8161e79e>] check_memory_region+0x13e/0x1a0
     [<ffffffff8161e9c1>] kasan_check_read+0x11/0x20
     [<ffffffff82c84b54>] snd_timer_user_read+0x554/0x790
     [<ffffffff82c84600>] ? snd_timer_user_info_compat.isra.5+0x2b0/0x2b0
     [<ffffffff817d0831>] ? proc_fault_inject_write+0x1c1/0x250
     [<ffffffff817d0670>] ? next_tgid+0x2a0/0x2a0
     [<ffffffff8127c278>] ? do_group_exit+0x108/0x330
     [<ffffffff8174653a>] ? fsnotify+0x72a/0xca0
     [<ffffffff81674dfe>] __vfs_read+0x10e/0x550
     [<ffffffff82c84600>] ? snd_timer_user_info_compat.isra.5+0x2b0/0x2b0
     [<ffffffff81674cf0>] ? do_sendfile+0xc50/0xc50
     [<ffffffff81745e10>] ? __fsnotify_update_child_dentry_flags+0x60/0x60
     [<ffffffff8143fec6>] ? kcov_ioctl+0x56/0x190
     [<ffffffff81e5ada2>] ? common_file_perm+0x2e2/0x380
     [<ffffffff81746b0e>] ? __fsnotify_parent+0x5e/0x2b0
     [<ffffffff81d93536>] ? security_file_permission+0x86/0x1e0
     [<ffffffff816728f5>] ? rw_verify_area+0xe5/0x2b0
     [<ffffffff81675355>] vfs_read+0x115/0x330
     [<ffffffff81676371>] SyS_read+0xd1/0x1a0
     [<ffffffff816762a0>] ? vfs_write+0x4b0/0x4b0
     [<ffffffff82001c2c>] ? __this_cpu_preempt_check+0x1c/0x20
     [<ffffffff8150455a>] ? __context_tracking_exit.part.4+0x3a/0x1e0
     [<ffffffff816762a0>] ? vfs_write+0x4b0/0x4b0
     [<ffffffff81005524>] do_syscall_64+0x1c4/0x4e0
     [<ffffffff810052fc>] ? syscall_return_slowpath+0x16c/0x1d0
     [<ffffffff83c3276a>] entry_SYSCALL64_slow_path+0x25/0x25
    ==================================================================

There are a couple of problems that I can see:

 - ioctl(SNDRV_TIMER_IOCTL_SELECT), which potentially sets
   tu->queue/tu->tqueue to NULL on memory allocation failure, so read()
   would get a NULL pointer dereference like the above splat

 - the same ioctl() can free tu->queue/to->tqueue which means read()
   could potentially see (and dereference) the freed pointer

We can fix both by taking the ioctl_lock mutex when dereferencing
->queue/->tqueue, since that's always held over all the ioctl() code.

Just looking at the code I find it likely that there are more problems
here such as tu->qhead pointing outside the buffer if the size is
changed concurrently using SNDRV_TIMER_IOCTL_PARAMS.
Signed-off-by: NVegard Nossum <vegard.nossum@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

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: NVegard Nossum <vegard.nossum@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

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: NVegard Nossum <vegard.nossum@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

The user timer tu->qused counter may go to a negative value when
multiple concurrent reads are performed since both the check and the
decrement of tu->qused are done in two individual locked contexts.
This results in bogus read outs, and the endless loop in the
user-space side.

The fix is to move the decrement of the tu->qused counter into the
same spinlock context as the zero-check of the counter.

Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

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: NKangjie Lu <kjlu@gatech.edu>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

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: NKangjie Lu <kjlu@gatech.edu>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

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: NKangjie Lu <kjlu@gatech.edu>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

There are no users of rtctimer left. Remove its code as this is the
in-kernel user of the legacy PC RTC driver that will hopefully be removed
at some point.
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

ALSA system timer backend stops the timer via del_timer() without sync
and leaves del_timer_sync() at the close instead.  This is because of
the restriction by the design of ALSA timer: namely, the stop callback
may be called from the timer handler, and calling the sync shall lead
to a hangup.  However, this also triggers a kernel BUG() when the
timer is rearmed immediately after stopping without sync:
 kernel BUG at kernel/time/timer.c:966!
 Call Trace:
  <IRQ>
  [<ffffffff8239c94e>] snd_timer_s_start+0x13e/0x1a0
  [<ffffffff8239e1f4>] snd_timer_interrupt+0x504/0xec0
  [<ffffffff8122fca0>] ? debug_check_no_locks_freed+0x290/0x290
  [<ffffffff8239ec64>] snd_timer_s_function+0xb4/0x120
  [<ffffffff81296b72>] call_timer_fn+0x162/0x520
  [<ffffffff81296add>] ? call_timer_fn+0xcd/0x520
  [<ffffffff8239ebb0>] ? snd_timer_interrupt+0xec0/0xec0
  ....

It's the place where add_timer() checks the pending timer.  It's clear
that this may happen after the immediate restart without sync in our
cases.

So, the workaround here is just to use mod_timer() instead of
add_timer().  This looks like a band-aid fix, but it's a right move,
as snd_timer_interrupt() takes care of the continuous rearm of timer.
Reported-by: NJiri Slaby <jslaby@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

'struct snd_timer_gparams' includes some members with 'unsigned long',
therefore its size differs depending on data models of architecture. As
a result, x86/x32 applications fail to execute ioctl(2) with
SNDRV_TIMER_GPARAMS command on x86_64 machine.

This commit fixes this bug by adding a pair of structure and ioctl
command for the compatibility.
Signed-off-by: NTakashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

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: NTakashi Iwai <tiwai@suse.de>

In order to make the open/close more robust, widen the register_mutex
protection over the whole snd_timer_close() function.  Also, the close
procedure is slightly shuffled to be in the safer order, as well as a
few code refactoring.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

snd_timer_user_read() has a potential race among parallel reads, as
qhead and qused are updated outside the critical section due to
copy_to_user() calls.  Move them into the critical section, and also
sanitize the relevant code a bit.

Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

A slave timer element also unlinks at snd_timer_stop() but it takes
only slave_active_lock.  When a slave is assigned to a master,
however, this may become a race against the master's interrupt
handling, eventually resulting in a list corruption.  The actual bug
could be seen with a syzkaller fuzzer test case in BugLink below.

As a fix, we need to take timeri->timer->lock when timer isn't NULL,
i.e. assigned to a master, while the assignment to a master itself is
protected by slave_active_lock.

BugLink: http://lkml.kernel.org/r/CACT4Y+Y_Bm+7epAb=8Wi=AaWd+DYS7qawX52qxdCfOfY49vozQ@mail.gmail.com
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

In snd_timer_notify1(), the wrong timer instance was passed for slave
ccallback function.  This leads to the access to the wrong data when
an incompatible master is handled (e.g. the master is the sequencer
timer and the slave is a user timer), as spotted by syzkaller fuzzer.

This patch fixes that wrong assignment.

BugLink: http://lkml.kernel.org/r/CACT4Y+Y_Bm+7epAb=8Wi=AaWd+DYS7qawX52qxdCfOfY49vozQ@mail.gmail.comReported-by: NDmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

In ALSA timer core, the active timer instance is managed in
active_list linked list.  Each element is added / removed dynamically
at timer start, stop and in timer interrupt.  The problem is that
snd_timer_interrupt() has a thinko and leaves the element in
active_list when it's the last opened element.  This eventually leads
to list corruption or use-after-free error.

This hasn't been revealed because we used to delete the list forcibly
in snd_timer_stop() in the past.  However, the recent fix avoids the
double-stop behavior (in commit [f784beb7: ALSA: timer: Fix link
corruption due to double start or stop]), and this leak hits reality.

This patch fixes the link management in snd_timer_interrupt().  Now it
simply unlinks no matter which stream is.

BugLink: http://lkml.kernel.org/r/CACT4Y+Yy2aukHP-EDp8-ziNqNNmb-NTf=jDWXMP7jB8HDa2vng@mail.gmail.comReported-by: NDmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

ALSA timer core framework has no sync point at stopping because it's
called inside the spinlock.  Thus we need a sync point at close for
avoiding the stray timer task.  This is simply done by implementing
the close callback just calling del_timer_sync().  (It's harmless to
call it unconditionally, as the core timer itself cares of the already
deleted timer instance.)
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Although ALSA timer code got hardening for races, it still causes
use-after-free error.  This is however rather a corrupted linked list,
not actually the concurrent accesses.  Namely, when timer start is
triggered twice, list_add_tail() is called twice, too.  This ends
up with the link corruption and triggers KASAN error.

The simplest fix would be replacing list_add_tail() with
list_move_tail(), but fundamentally it's the problem that we don't
check the double start/stop correctly.  So, the right fix here is to
add the proper checks to snd_timer_start() and snd_timer_stop() (and
their variants).

BugLink: http://lkml.kernel.org/r/CACT4Y+ZyPRoMQjmawbvmCEDrkBD2BQuH7R09=eOkf5ESK8kJAw@mail.gmail.comReported-by: NDmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Instead of the previous ugly hack, introduce a new op, disconnect, to
snd_timer_instance object for handling the wake up of pending tasks
more cleanly.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=109431Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Currently ALSA timer device doesn't take the disconnection into
account very well; it merely unlinks the timer device at disconnection
callback but does nothing else.  Because of this, when an application
accessing the timer device is disconnected, it may release the
resource before actually closed.  In most cases, it results in a
warning message indicating a leftover timer instance like:
   ALSA: timer xxxx is busy?
But basically this is an open race.

This patch tries to address it.  The strategy is like other ALSA
devices: namely,
- Manage card's refcount at each open/close
- Wake up the pending tasks at disconnection
- Check the shutdown flag appropriately at each possible call

Note that this patch has one ugly hack to handle the wakeup of pending
tasks.  It'd be cleaner to introduce a new disconnect op to
snd_timer_instance ops.  But since it would lead to internal ABI
breakage and it eventually increase my own work when backporting to
stable kernels, I took a different path to implement locally in
timer.c.  A cleanup patch will follow at next for 4.5 kernel.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=109431
Cc: <stable@vger.kernel.org> # v3.15+
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

This is a minor code cleanup without any functional changes:
- Kill keep_flag argument from _snd_timer_stop(), as all callers pass
  only it false.
- Remove redundant NULL check in _snd_timer_stop().
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

A slave timer instance might be still accessible in a racy way while
operating the master instance as it lacks of locking.  Since the
master operation is mostly protected with timer->lock, we should cope
with it while changing the slave instance, too.  Also, some linked
lists (active_list and ack_list) of slave instances aren't unlinked
immediately at stopping or closing, and this may lead to unexpected
accesses.

This patch tries to address these issues.  It adds spin lock of
timer->lock (either from master or slave, which is equivalent) in a
few places.  For avoiding a deadlock, we ensure that the global
slave_active_lock is always locked at first before each timer lock.

Also, ack and active_list of slave instances are properly unlinked at
snd_timer_stop() and snd_timer_close().

Last but not least, remove the superfluous call of _snd_timer_stop()
at removing slave links.  This is a noop, and calling it may confuse
readers wrt locking.  Further cleanup will follow in a later patch.

Actually we've got reports of use-after-free by syzkaller fuzzer, and
this hopefully fixes these issues.
Reported-by: NDmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

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: NDmitry Vyukov <dvyukov@google.com>
Tested-by: NDmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

ALSA timer instance object has a couple of linked lists and they are
unlinked unconditionally at snd_timer_stop().  Meanwhile
snd_timer_interrupt() unlinks it, but it calls list_del() which leaves
the element list itself unchanged.  This ends up with unlinking twice,
and it was caught by syzkaller fuzzer.

The fix is to use list_del_init() variant properly there, too.
Reported-by: NDmitry Vyukov <dvyukov@google.com>
Tested-by: NDmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

We may disable proc fs only for sound part, to reduce ALSA
memory footprint. So add CONFIG_SND_PROC_FS and replace the
old CONFIG_PROC_FSs in alsa code.

With sound proc fs disabled, we can save about 9KB memory
size on X86_64 platform.
Signed-off-by: NJie Yang <yang.jie@intel.com>
Reviewed-by: NMark Brown <broonie@kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

The kernel memory allocators already report the errors when the
requested allocation fails, thus we don't need to warn it again in
each caller side.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>