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linux-2.6.32.y
linux-stable/include
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Takashi Iwai 1378f539a5 ALSA: rawmidi: Make snd_rawmidi_transmit() race-free 
commit 06ab30034e upstream.

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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Willy Tarreau <w@1wt.eu>
2016-03-12 14:25:46 +01:00
..
acpi ACPI: skip checking BM_STS if the BIOS doesn't ask for it 2010-08-02 10:21:24 -07:00
asm-generic signal: Define __ARCH_HAS_SA_RESTORER so we know whether to clear sa_restorer 2013-06-10 11:42:21 +02:00
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2009-09-11 09:38:37 -07:00
drm drm: Fix authentication kernel crash 2012-02-03 09:26:50 -08:00
keys RxRPC: Fix v1 keys 2011-03-14 14:29:53 -07:00
linux readv/writev: do the same MAX_RW_COUNT truncation that read/write does 2016-03-12 14:25:41 +01:00
math-emu math-emu: correct test for downshifting fraction in _FP_FROM_INT() 2010-08-02 10:20:44 -07:00
media V4L/DVB (13019): video: initial support for ADV7180 2009-09-19 00:53:39 -03:00
mtd
net af_unix: fix a fatal race with bit fields 2016-01-29 22:12:50 +01:00
pcmcia PM / yenta: Split resume into early and late parts (rev. 4) 2009-11-03 10:54:58 +01:00
rdma trivial: fix typo "to to" in multiple files 2009-09-21 15:14:55 +02:00
rxrpc
scsi scsi: fix missing include linux/types.h in scsi_netlink.h 2014-05-19 07:53:10 +02:00
sound ALSA: rawmidi: Make snd_rawmidi_transmit() race-free 2016-03-12 14:25:46 +01:00
trace tracing: Don't call page_to_pfn() if page is NULL 2013-06-10 11:42:27 +02:00
video davinci-fb-frame-buffer-driver-for-ti-da8xx-omap-l1xx-v4 2009-09-23 07:39:51 -07:00
xen xen/xenbus: Reject replies with payload > XENSTORE_PAYLOAD_MAX. 2012-01-25 13:53:20 -08:00
Kbuild [SCSI] FC Pass Thru support 2009-06-12 14:20:05 -05:00