From 4d3a869333b74352c372077f316756d38cae09b1 Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Fri, 11 Aug 2017 09:51:41 +0200 Subject: ALSA: seq: Fix CONFIG_SND_SEQ_MIDI dependency The commit 0181307abc1d ("ALSA: seq: Reorganize kconfig and build") rewrote the dependency of each sequencer module in a standard way, but there was one change applied mistakenly: CONFIG_SND_SEQ_MIDI isn't enabled properly by CONFIG_SND_RAWMIDI. I seem to have changed the wrong one instead, CONFIG_SND_SEQ_MIDI_EMUL, which is eventually reverse-selected by CONFIG_SND_SEQ_MIDI itself. This ended up the lack of snd-seq-midi module as reported below. The fix is to put def_tristate properly to CONFIG_SND_SEQ_MIDI instead of *_MIDI_EMUL entry. Fixes: 0181307abc1d ("ALSA: seq: Reorganize kconfig and build") Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=196633 Signed-off-by: Takashi Iwai --- sound/core/seq/Kconfig | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'sound/core') diff --git a/sound/core/seq/Kconfig b/sound/core/seq/Kconfig index a536760a94c2..45c1336c6597 100644 --- a/sound/core/seq/Kconfig +++ b/sound/core/seq/Kconfig @@ -47,10 +47,10 @@ config SND_SEQ_HRTIMER_DEFAULT timer. config SND_SEQ_MIDI_EVENT - def_tristate SND_RAWMIDI + tristate config SND_SEQ_MIDI - tristate + def_tristate SND_RAWMIDI select SND_SEQ_MIDI_EVENT config SND_SEQ_MIDI_EMUL -- cgit v1.2.3-55-g7522 From 7e1d90f60a0d501c8503e636942ca704a454d910 Mon Sep 17 00:00:00 2001 From: Daniel Mentz Date: Mon, 14 Aug 2017 14:46:01 -0700 Subject: ALSA: seq: 2nd attempt at fixing race creating a queue commit 4842e98f26dd80be3623c4714a244ba52ea096a8 ("ALSA: seq: Fix race at creating a queue") attempted to fix a race reported by syzkaller. That fix has been described as follows: " When a sequencer queue is created in snd_seq_queue_alloc(),it adds the new queue element to the public list before referencing it. Thus the queue might be deleted before the call of snd_seq_queue_use(), and it results in the use-after-free error, as spotted by syzkaller. The fix is to reference the queue object at the right time. " Even with that fix in place, syzkaller reported a use-after-free error. It specifically pointed to the last instruction "return q->queue" in snd_seq_queue_alloc(). The pointer q is being used after kfree() has been called on it. It turned out that there is still a small window where a race can happen. The window opens at snd_seq_ioctl_create_queue()->snd_seq_queue_alloc()->queue_list_add() and closes at snd_seq_ioctl_create_queue()->queueptr()->snd_use_lock_use(). Between these two calls, a different thread could delete the queue and possibly re-create a different queue in the same location in queue_list. This change prevents this situation by calling snd_use_lock_use() from snd_seq_queue_alloc() prior to calling queue_list_add(). It is then the caller's responsibility to call snd_use_lock_free(&q->use_lock). Fixes: 4842e98f26dd ("ALSA: seq: Fix race at creating a queue") Reported-by: Dmitry Vyukov Cc: Signed-off-by: Daniel Mentz Signed-off-by: Takashi Iwai --- sound/core/seq/seq_clientmgr.c | 13 ++++--------- sound/core/seq/seq_queue.c | 14 +++++++++----- sound/core/seq/seq_queue.h | 2 +- 3 files changed, 14 insertions(+), 15 deletions(-) (limited to 'sound/core') diff --git a/sound/core/seq/seq_clientmgr.c b/sound/core/seq/seq_clientmgr.c index 272c55fe17c8..ea2d0ae85bd3 100644 --- a/sound/core/seq/seq_clientmgr.c +++ b/sound/core/seq/seq_clientmgr.c @@ -1502,16 +1502,11 @@ static int snd_seq_ioctl_unsubscribe_port(struct snd_seq_client *client, static int snd_seq_ioctl_create_queue(struct snd_seq_client *client, void *arg) { struct snd_seq_queue_info *info = arg; - int result; struct snd_seq_queue *q; - result = snd_seq_queue_alloc(client->number, info->locked, info->flags); - if (result < 0) - return result; - - q = queueptr(result); - if (q == NULL) - return -EINVAL; + q = snd_seq_queue_alloc(client->number, info->locked, info->flags); + if (IS_ERR(q)) + return PTR_ERR(q); info->queue = q->queue; info->locked = q->locked; @@ -1521,7 +1516,7 @@ static int snd_seq_ioctl_create_queue(struct snd_seq_client *client, void *arg) if (!info->name[0]) snprintf(info->name, sizeof(info->name), "Queue-%d", q->queue); strlcpy(q->name, info->name, sizeof(q->name)); - queuefree(q); + snd_use_lock_free(&q->use_lock); return 0; } diff --git a/sound/core/seq/seq_queue.c b/sound/core/seq/seq_queue.c index 450c5187eecb..79e0c5604ef8 100644 --- a/sound/core/seq/seq_queue.c +++ b/sound/core/seq/seq_queue.c @@ -184,22 +184,26 @@ void __exit snd_seq_queues_delete(void) static void queue_use(struct snd_seq_queue *queue, int client, int use); /* allocate a new queue - - * return queue index value or negative value for error + * return pointer to new queue or ERR_PTR(-errno) for error + * The new queue's use_lock is set to 1. It is the caller's responsibility to + * call snd_use_lock_free(&q->use_lock). */ -int snd_seq_queue_alloc(int client, int locked, unsigned int info_flags) +struct snd_seq_queue *snd_seq_queue_alloc(int client, int locked, unsigned int info_flags) { struct snd_seq_queue *q; q = queue_new(client, locked); if (q == NULL) - return -ENOMEM; + return ERR_PTR(-ENOMEM); q->info_flags = info_flags; queue_use(q, client, 1); + snd_use_lock_use(&q->use_lock); if (queue_list_add(q) < 0) { + snd_use_lock_free(&q->use_lock); queue_delete(q); - return -ENOMEM; + return ERR_PTR(-ENOMEM); } - return q->queue; + return q; } /* delete a queue - queue must be owned by the client */ diff --git a/sound/core/seq/seq_queue.h b/sound/core/seq/seq_queue.h index 30c8111477f6..719093489a2c 100644 --- a/sound/core/seq/seq_queue.h +++ b/sound/core/seq/seq_queue.h @@ -71,7 +71,7 @@ void snd_seq_queues_delete(void); /* create new queue (constructor) */ -int snd_seq_queue_alloc(int client, int locked, unsigned int flags); +struct snd_seq_queue *snd_seq_queue_alloc(int client, int locked, unsigned int flags); /* delete queue (destructor) */ int snd_seq_queue_delete(int client, int queueid); -- cgit v1.2.3-55-g7522 From 88c54cdf61f508ebcf8da2d819f5dfc03e954d1d Mon Sep 17 00:00:00 2001 From: Takashi Iwai Date: Tue, 22 Aug 2017 08:15:13 +0200 Subject: ALSA: core: Fix unexpected error at replacing user TLV When user tries to replace the user-defined control TLV, the kernel checks the change of its content via memcmp(). The problem is that the kernel passes the return value from memcmp() as is. memcmp() gives a non-zero negative value depending on the comparison result, and this shall be recognized as an error code. The patch covers that corner-case, return 1 properly for the changed TLV. Fixes: 8aa9b586e420 ("[ALSA] Control API - more robust TLV implementation") Cc: Signed-off-by: Takashi Iwai --- sound/core/control.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'sound/core') diff --git a/sound/core/control.c b/sound/core/control.c index 3c6be1452e35..4525e127afd9 100644 --- a/sound/core/control.c +++ b/sound/core/control.c @@ -1137,7 +1137,7 @@ static int snd_ctl_elem_user_tlv(struct snd_kcontrol *kcontrol, mutex_lock(&ue->card->user_ctl_lock); change = ue->tlv_data_size != size; if (!change) - change = memcmp(ue->tlv_data, new_data, size); + change = memcmp(ue->tlv_data, new_data, size) != 0; kfree(ue->tlv_data); ue->tlv_data = new_data; ue->tlv_data_size = size; -- cgit v1.2.3-55-g7522