kernel.git/sound/core/timer.c, branch linux-4.1.y

ALSA: timer: Fix missing queue indices reset at SNDRV_TIMER_IOCTL_SELECT

2017-06-26T02:02:20Z

[ Upstream commit ba3021b2c79b2fa9114f92790a99deb27a65b728 ] 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 Tested-by: Alexander Potapenko Cc: Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: timer: Fix race between read and ioctl

2017-06-26T02:02:19Z

[ Upstream commit d11662f4f798b50d8c8743f433842c3e40fe3378 ] 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 Tested-by: Alexander Potapenko Cc: Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: timer: Reject user params with too small ticks

2017-05-17T19:07:00Z

[ Upstream commit 71321eb3f2d0df4e6c327e0b936eec4458a12054 ] 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: Dmitry Vyukov Cc: Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: timer: Fix zero-division by continue of uninitialized instance

2016-10-03T00:26:10Z

[ 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:[] [< inline >] ktime_divns include/linux/ktime.h:195 RIP: 0010:[] [] snd_hrtimer_callback+0x1bc/0x3c0 sound/core/hrtimer.c:62 Call Trace: [< inline >] __run_hrtimer kernel/time/hrtimer.c:1238 [] __hrtimer_run_queues+0x325/0xe70 kernel/time/hrtimer.c:1302 [] hrtimer_interrupt+0x18b/0x420 kernel/time/hrtimer.c:1336 [] local_apic_timer_interrupt+0x6f/0xe0 arch/x86/kernel/apic/apic.c:933 [] smp_apic_timer_interrupt+0x76/0xa0 arch/x86/kernel/apic/apic.c:957 [] apic_timer_interrupt+0x8c/0xa0 arch/x86/entry/entry_64.S:487 ..... 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 Cc: Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: timer: Call notifier in the same spinlock

2016-10-03T00:26:02Z

[ 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 Signed-off-by: Sasha Levin

ALSA: timer: fix NULL pointer dereference in read()/ioctl() race

2016-10-02T22:07:22Z

[ Upstream commit 11749e086b2766cccf6217a527ef5c5604ba069c ] 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: [] dump_stack+0x83/0xb2 [] kasan_report_error+0x41f/0x4c0 [] kasan_report+0x34/0x40 [] ? snd_timer_user_read+0x554/0x790 [] check_memory_region+0x13e/0x1a0 [] kasan_check_read+0x11/0x20 [] snd_timer_user_read+0x554/0x790 [] ? snd_timer_user_info_compat.isra.5+0x2b0/0x2b0 [] ? proc_fault_inject_write+0x1c1/0x250 [] ? next_tgid+0x2a0/0x2a0 [] ? do_group_exit+0x108/0x330 [] ? fsnotify+0x72a/0xca0 [] __vfs_read+0x10e/0x550 [] ? snd_timer_user_info_compat.isra.5+0x2b0/0x2b0 [] ? do_sendfile+0xc50/0xc50 [] ? __fsnotify_update_child_dentry_flags+0x60/0x60 [] ? kcov_ioctl+0x56/0x190 [] ? common_file_perm+0x2e2/0x380 [] ? __fsnotify_parent+0x5e/0x2b0 [] ? security_file_permission+0x86/0x1e0 [] ? rw_verify_area+0xe5/0x2b0 [] vfs_read+0x115/0x330 [] SyS_read+0xd1/0x1a0 [] ? vfs_write+0x4b0/0x4b0 [] ? __this_cpu_preempt_check+0x1c/0x20 [] ? __context_tracking_exit.part.4+0x3a/0x1e0 [] ? vfs_write+0x4b0/0x4b0 [] do_syscall_64+0x1c4/0x4e0 [] ? syscall_return_slowpath+0x16c/0x1d0 [] 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: Vegard Nossum Cc: Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: timer: fix NULL pointer dereference on memory allocation failure

2016-10-02T16:51:03Z

[ 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:[] [] 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: [] snd_timer_start1+0x331/0x670 [] snd_timer_start+0x5d/0xa0 [] snd_timer_user_ioctl+0x88e/0x2830 [] ? __follow_pte.isra.49+0x430/0x430 [] ? snd_timer_pause+0x80/0x80 [] ? do_wp_page+0x3aa/0x1c90 [] ? put_prev_entity+0x108f/0x21a0 [] ? snd_timer_pause+0x80/0x80 [] do_vfs_ioctl+0x193/0x1050 [] ? cpuacct_account_field+0x12f/0x1a0 [] ? ioctl_preallocate+0x200/0x200 [] ? syscall_trace_enter+0x3cf/0xdb0 [] ? __context_tracking_exit.part.4+0x9a/0x1e0 [] ? exit_to_usermode_loop+0x190/0x190 [] ? check_preemption_disabled+0x37/0x1e0 [] ? security_file_ioctl+0x89/0xb0 [] SyS_ioctl+0x8f/0xc0 [] ? do_vfs_ioctl+0x1050/0x1050 [] do_syscall_64+0x1c4/0x4e0 [] 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 [] snd_hrtimer_start+0x77/0x100 RSP ---[ 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 Cc: Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: timer: fix division by zero after SNDRV_TIMER_IOCTL_CONTINUE

2016-10-02T16:50:57Z

[ 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:[] [] 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: [] __hrtimer_run_queues+0x347/0xa00 [] ? snd_hrtimer_close+0x130/0x130 [] ? retrigger_next_event+0x1b0/0x1b0 [] ? hrtimer_interrupt+0x136/0x4b0 [] hrtimer_interrupt+0x1b0/0x4b0 [] local_apic_timer_interrupt+0x6e/0xf0 [] ? kvm_guest_apic_eoi_write+0x13/0xc0 [] smp_apic_timer_interrupt+0x76/0xa0 [] apic_timer_interrupt+0x8c/0xa0 [] ? _raw_spin_unlock_irqrestore+0x2c/0x60 [] snd_timer_start1+0xdd/0x670 [] snd_timer_continue+0x45/0x80 [] snd_timer_user_ioctl+0x1030/0x2830 [] ? __follow_pte.isra.49+0x430/0x430 [] ? snd_timer_pause+0x80/0x80 [] ? do_wp_page+0x3aa/0x1c90 [] ? handle_mm_fault+0xbc8/0x27f0 [] ? __pmd_alloc+0x370/0x370 [] ? snd_timer_pause+0x80/0x80 [] do_vfs_ioctl+0x193/0x1050 [] ? ioctl_preallocate+0x200/0x200 [] ? syscall_trace_enter+0x3cf/0xdb0 [] ? __context_tracking_exit.part.4+0x9a/0x1e0 [] ? exit_to_usermode_loop+0x190/0x190 [] ? check_preemption_disabled+0x37/0x1e0 [] ? security_file_ioctl+0x89/0xb0 [] SyS_ioctl+0x8f/0xc0 [] ? do_vfs_ioctl+0x1050/0x1050 [] do_syscall_64+0x1c4/0x4e0 [] 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 [] snd_hrtimer_callback+0x1da/0x3f0 RSP ---[ 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 Cc: Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: timer: Fix leak in events via snd_timer_user_tinterrupt

2016-08-20T03:08:47Z

[ Upstream commit e4ec8cc8039a7063e24204299b462bd1383184a5 ] 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 Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin

ALSA: timer: Fix leak in events via snd_timer_user_ccallback

2016-08-20T03:08:46Z

[ Upstream commit 9a47e9cff994f37f7f0dbd9ae23740d0f64f9fe6 ] 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 Signed-off-by: Takashi Iwai Signed-off-by: Sasha Levin