linux_dsm_epyc7002/sound
Takashi Iwai 06ab30034e ALSA: rawmidi: Make snd_rawmidi_transmit() race-free
A kernel WARNING in snd_rawmidi_transmit_ack() is triggered by
syzkaller fuzzer:
  WARNING: CPU: 1 PID: 20739 at sound/core/rawmidi.c:1136
Call Trace:
 [<     inline     >] __dump_stack lib/dump_stack.c:15
 [<ffffffff82999e2d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
 [<ffffffff81352089>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482
 [<ffffffff813522b9>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515
 [<ffffffff84f80bd5>] snd_rawmidi_transmit_ack+0x275/0x400 sound/core/rawmidi.c:1136
 [<ffffffff84fdb3c1>] snd_virmidi_output_trigger+0x4b1/0x5a0 sound/core/seq/seq_virmidi.c:163
 [<     inline     >] snd_rawmidi_output_trigger sound/core/rawmidi.c:150
 [<ffffffff84f87ed9>] snd_rawmidi_kernel_write1+0x549/0x780 sound/core/rawmidi.c:1223
 [<ffffffff84f89fd3>] snd_rawmidi_write+0x543/0xb30 sound/core/rawmidi.c:1273
 [<ffffffff817b0323>] __vfs_write+0x113/0x480 fs/read_write.c:528
 [<ffffffff817b1db7>] vfs_write+0x167/0x4a0 fs/read_write.c:577
 [<     inline     >] SYSC_write fs/read_write.c:624
 [<ffffffff817b50a1>] SyS_write+0x111/0x220 fs/read_write.c:616
 [<ffffffff86336c36>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185

Also a similar warning is found but in another path:
Call Trace:
 [<     inline     >] __dump_stack lib/dump_stack.c:15
 [<ffffffff82be2c0d>] dump_stack+0x6f/0xa2 lib/dump_stack.c:50
 [<ffffffff81355139>] warn_slowpath_common+0xd9/0x140 kernel/panic.c:482
 [<ffffffff81355369>] warn_slowpath_null+0x29/0x30 kernel/panic.c:515
 [<ffffffff8527e69a>] rawmidi_transmit_ack+0x24a/0x3b0 sound/core/rawmidi.c:1133
 [<ffffffff8527e851>] snd_rawmidi_transmit_ack+0x51/0x80 sound/core/rawmidi.c:1163
 [<ffffffff852d9046>] snd_virmidi_output_trigger+0x2b6/0x570 sound/core/seq/seq_virmidi.c:185
 [<     inline     >] snd_rawmidi_output_trigger sound/core/rawmidi.c:150
 [<ffffffff85285a0b>] snd_rawmidi_kernel_write1+0x4bb/0x760 sound/core/rawmidi.c:1252
 [<ffffffff85287b73>] snd_rawmidi_write+0x543/0xb30 sound/core/rawmidi.c:1302
 [<ffffffff817ba5f3>] __vfs_write+0x113/0x480 fs/read_write.c:528
 [<ffffffff817bc087>] vfs_write+0x167/0x4a0 fs/read_write.c:577
 [<     inline     >] SYSC_write fs/read_write.c:624
 [<ffffffff817bf371>] SyS_write+0x111/0x220 fs/read_write.c:616
 [<ffffffff86660276>] entry_SYSCALL_64_fastpath+0x16/0x7a arch/x86/entry/entry_64.S:185

In the former case, the reason is that virmidi has an open code
calling snd_rawmidi_transmit_ack() with the value calculated outside
the spinlock.   We may use snd_rawmidi_transmit() in a loop just for
consuming the input data, but even there, there is a race between
snd_rawmidi_transmit_peek() and snd_rawmidi_tranmit_ack().

Similarly in the latter case, it calls snd_rawmidi_transmit_peek() and
snd_rawmidi_tranmit_ack() separately without protection, so they are
racy as well.

The patch tries to address these issues by the following ways:
- Introduce the unlocked versions of snd_rawmidi_transmit_peek() and
  snd_rawmidi_transmit_ack() to be called inside the explicit lock.
- Rewrite snd_rawmidi_transmit() to be race-free (the former case).
- Make the split calls (the latter case) protected in the rawmidi spin
  lock.

BugLink: http://lkml.kernel.org/r/CACT4Y+YPq1+cYLkadwjWa5XjzF1_Vki1eHnVn-Lm0hzhSpu5PA@mail.gmail.com
BugLink: http://lkml.kernel.org/r/CACT4Y+acG4iyphdOZx47Nyq_VHGbpJQK-6xNpiqUjaZYqsXOGw@mail.gmail.com
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
2016-02-03 14:51:28 +01:00
..
aoa ALSA: aoa-soundbus: Switch to dev_pm_ops 2015-08-05 16:47:47 +02:00
arm ASoC: pxa: pxa-pcm-lib: switch over to snd-soc-dmaengine-pcm 2015-09-30 23:21:16 +01:00
atmel ALSA: sound/atmel/ac97c.c: remove unused variable 2015-05-20 06:18:25 +02:00
core ALSA: rawmidi: Make snd_rawmidi_transmit() race-free 2016-02-03 14:51:28 +01:00
drivers ALSA: dummy: Disable switching timer backend via sysfs 2016-01-28 08:13:54 +01:00
firewire ALSA: bebob: Use a signed return type for get_formation_index 2016-01-26 11:38:53 +01:00
hda ALSA: hda - Degrade i915 binding failure message 2016-01-20 15:00:26 +01:00
i2c ALSA: i2c: constify snd_i2c_ops structures 2015-11-30 11:40:08 +01:00
isa ALSA: Add missing dependency on CONFIG_SND_TIMER 2016-01-27 07:10:38 +01:00
mips ALSA: mips: let SND_SGI_O2 select SND_PCM 2015-06-15 13:21:58 +02:00
oss sound/oss: remove VIRT_TO_BUS dependency 2015-12-09 14:40:51 +01:00
parisc ALSA: Include linux/io.h instead of asm/io.h 2015-01-28 16:49:33 +01:00
pci ALSA: emu10k1: correctly handling failed thread creation 2016-01-29 17:30:25 +01:00
pcmcia
ppc ALSA: ppc: Add missing inclusion of linux/module.h 2015-08-25 14:13:36 +02:00
sh ALSA: Include linux/io.h instead of asm/io.h 2015-01-28 16:49:33 +01:00
soc ARM: SoC multiplatform code changes for v4.5 2016-01-20 18:03:56 -08:00
sparc ALSA: Add missing dependency on CONFIG_SND_TIMER 2016-01-27 07:10:38 +01:00
spi ALSA: at73c213: manage SSC clock 2016-01-20 09:59:27 +01:00
synth ALSA: emux: constify nrpn_conv_table structures 2016-01-06 10:19:49 +01:00
usb ALSA: usb-audio: Add quirk for Microsoft LifeCam HD-6000 2016-01-29 17:25:39 +01:00
ac97_bus.c ASoC: Updates for v4.3 2015-08-31 16:25:22 +02:00
Kconfig ALSA: hda - Make snd_hda_bus_type public 2015-03-23 13:15:51 +01:00
last.c
Makefile ALSA: hda - Make snd_hda_bus_type public 2015-03-23 13:15:51 +01:00
sound_core.c sound: fix check for error condition of register_chrdev() 2015-11-07 11:14:30 +01:00
sound_firmware.c sound: sound_firmware: Fix invalid use of vfs_read() 2015-05-26 13:48:58 +02:00