BMC/Intel-BMC/linux.git/sound/core, branch dev-4.19

ALSA: compress: prevent potential divide by zero bugs

2019-03-05T16:58:45+00:00

[ Upstream commit 678e2b44c8e3fec3afc7202f1996a4500a50be93 ] The problem is seen in the q6asm_dai_compr_set_params() function: ret = q6asm_map_memory_regions(dir, prtd->audio_client, prtd->phys, (prtd->pcm_size / prtd->periods), ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ prtd->periods); In this code prtd->pcm_size is the buffer_size and prtd->periods comes from params->buffer.fragments. If we allow the number of fragments to be zero then it results in a divide by zero bug. One possible fix would be to use prtd->pcm_count directly instead of using the division to re-calculate it. But I decided that it doesn't really make sense to allow zero fragments. Signed-off-by: Dan Carpenter Signed-off-by: Mark Brown Signed-off-by: Sasha Levin

ALSA: pcm: Fix potential Spectre v1 vulnerability

2019-01-09T16:38:36+00:00

commit 94ffb030b6d31ec840bb811be455dd2e26a4f43e upstream. stream is indirectly controlled by user-space, hence leading to a potential exploitation of the Spectre variant 1 vulnerability. This issue was detected with the help of Smatch: sound/core/pcm.c:140 snd_pcm_control_ioctl() warn: potential spectre issue 'pcm->streams' [r] (local cap) Fix this by sanitizing stream before using it to index pcm->streams Notice that given that speculation windows are large, the policy is to kill the speculation on the first load and not worry if it can be completed with a dependent load/store [1]. [1] https://marc.info/?l=linux-kernel&m=152449131114778&w=2 Signed-off-by: Gustavo A. R. Silva Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: pcm: Call snd_pcm_unlink() conditionally at closing

2018-12-13T08:16:16+00:00

commit b51abed8355e5556886623b2772fa6b7598d2282 upstream. Currently the PCM core calls snd_pcm_unlink() always unconditionally at closing a stream. However, since snd_pcm_unlink() invokes the global rwsem down, the lock can be easily contended. More badly, when a thread runs in a high priority RT-FIFO, it may stall at spinning. Basically the call of snd_pcm_unlink() is required only for the linked streams that are already rare occasion. For normal use cases, this code path is fairly superfluous. As an optimization (and also as a workaround for the RT problem above in normal situations without linked streams), this patch adds a check before calling snd_pcm_unlink() and calls it only when needed. Reported-by: Chanho Min Cc: Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: pcm: Fix starvation on down_write_nonblock()

2018-12-13T08:16:16+00:00

commit b888a5f713e4d17faaaff24316585a4eb07f35b7 upstream. Commit 67ec1072b053 ("ALSA: pcm: Fix rwsem deadlock for non-atomic PCM stream") fixes deadlock for non-atomic PCM stream. But, This patch causes antother stuck. If writer is RT thread and reader is a normal thread, the reader thread will be difficult to get scheduled. It may not give chance to release readlocks and writer gets stuck for a long time if they are pinned to single cpu. The deadlock described in the previous commit is because the linux rwsem queues like a FIFO. So, we might need non-FIFO writelock, not non-block one. My suggestion is that the writer gives reader a chance to be scheduled by using the minimum msleep() instaed of spinning without blocking by writer. Also, The *_nonblock may be changed to *_nonfifo appropriately to this concept. In terms of performance, when trylock is failed, this minimum periodic msleep will have the same performance as the tick-based schedule()/wake_up_q(). [ Although this has a fairly high performance penalty, the relevant code path became already rare due to the previous commit ("ALSA: pcm: Call snd_pcm_unlink() conditionally at closing"). That is, now this unconditional msleep appears only when using linked streams, and this must be a rare case. So we accept this as a quick workaround until finding a more suitable one -- tiwai ] Fixes: 67ec1072b053 ("ALSA: pcm: Fix rwsem deadlock for non-atomic PCM stream") Suggested-by: Wonmin Jung Signed-off-by: Chanho Min Cc: Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: control: Fix race between adding and removing a user element

2018-12-05T18:32:08+00:00

commit e1a7bfe3807974e66f971f2589d4e0197ec0fced upstream. The procedure for adding a user control element has some window opened for race against the concurrent removal of a user element. This was caught by syzkaller, hitting a KASAN use-after-free error. This patch addresses the bug by wrapping the whole procedure to add a user control element with the card->controls_rwsem, instead of only around the increment of card->user_ctl_count. This required a slight code refactoring, too. The function snd_ctl_add() is split to two parts: a core function to add the control element and a part calling it. The former is called from the function for adding a user control element inside the controls_rwsem. One change to be noted is that snd_ctl_notify() for adding a control element gets called inside the controls_rwsem as well while it was called outside the rwsem. But this should be OK, as snd_ctl_notify() takes another (finer) rwlock instead of rwsem, and the call of snd_ctl_notify() inside rwsem is already done in another code path. Reported-by: syzbot+dc09047bce3820621ba2@syzkaller.appspotmail.com Cc: Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: oss: Use kvzalloc() for local buffer allocations

2018-12-01T08:37:25+00:00

commit 65766ee0bf7fe8b3be80e2e1c3ef54ad59b29476 upstream. PCM OSS layer may allocate a few temporary buffers, one for the core read/write and another for the conversions via plugins. Currently both are allocated via vmalloc(). But as the allocation size is equivalent with the PCM period size, the required size might be quite small, depending on the application. This patch replaces these vmalloc() calls with kvzalloc() for covering small period sizes better. Also, we use "z"-alloc variant here for addressing the possible uninitialized access reported by syzkaller. Reported-by: syzbot+1cb36954e127c98dd037@syzkaller.appspotmail.com Cc: Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman

ALSA: rawmidi: Initialize allocated buffers

2018-09-03T13:16:43+00:00

syzbot reported the uninitialized value exposure in certain situations using virmidi loop. It's likely a very small race at writing and reading, and the influence is almost negligible. But it's safer to paper over this just by replacing the existing kvmalloc() with kvzalloc(). Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai

ALSA: seq: virmidi: Fix discarding the unsubscribed output

2018-08-14T20:50:52+00:00

The recent change to move the virmidi output processing to a work slightly modified the code to discard the unsubscribed outputs so that it works without a temporary buffer. However, this is actually buggy, and may spew a kernel warning due to the unexpected call of snd_rawmidi_transmit_ack(), as triggered by syzbot. This patch takes back to the original code in that part, use a temporary buffer and simply repeat snd_rawmidi_transmit(), in order to address the regression. Fixes: f7debfe54090 ("ALSA: seq: virmidi: Offload the output event processing") Reported-by: syzbot+ec5f605c91812d200367@syzkaller.appspotmail.com Signed-off-by: Takashi Iwai

ALSA: seq_oss: Mark expected switch fall-through

2018-08-04T06:30:45+00:00

In preparation to enabling -Wimplicit-fallthrough, mark switch cases where we are expecting to fall through. Warning level 2 was used: -Wimplicit-fallthrough=2 Signed-off-by: Gustavo A. R. Silva Signed-off-by: Takashi Iwai

ALSA: seq: Mark expected switch fall-through

2018-08-04T06:30:36+00:00

In preparation to enabling -Wimplicit-fallthrough, mark switch cases where we are expecting to fall through. Notice that in this particular case, I replaced the code comment with a proper "fall through" annotation, which is what GCC is expecting to find. Signed-off-by: Gustavo A. R. Silva Signed-off-by: Takashi Iwai