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authorTakashi Iwai <tiwai@suse.de>2017-11-07 16:05:24 +0100
committerTakashi Iwai <tiwai@suse.de>2017-11-07 16:05:24 +0100
commit132d358b183ac6ad8b3fea32ad5e0663456d18d1 (patch)
treed8a8493cf13d43f4ed5e8e6d96b57b7de45ef195
parent3510c7aa069aa83a2de6dab2b41401a198317bdc (diff)
ALSA: seq: Fix OSS sysex delivery in OSS emulation
The SYSEX event delivery in OSS sequencer emulation assumed that the event is encoded in the variable-length data with the straight buffering. This was the normal behavior in the past, but during the development, the chained buffers were introduced for carrying more data, while the OSS code was left intact. As a result, when a SYSEX event with the chained buffer data is passed to OSS sequencer port, it may end up with the wrong memory access, as if it were having a too large buffer. This patch addresses the bug, by applying the buffer data expansion by the generic snd_seq_dump_var_event() helper function. Reported-by: syzbot <syzkaller@googlegroups.com> Reported-by: Mark Salyzyn <salyzyn@android.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de>
-rw-r--r--sound/core/seq/oss/seq_oss_midi.c4
-rw-r--r--sound/core/seq/oss/seq_oss_readq.c29
-rw-r--r--sound/core/seq/oss/seq_oss_readq.h2
3 files changed, 32 insertions, 3 deletions
diff --git a/sound/core/seq/oss/seq_oss_midi.c b/sound/core/seq/oss/seq_oss_midi.c
index aaff9ee32695..b30b2139e3f0 100644
--- a/sound/core/seq/oss/seq_oss_midi.c
+++ b/sound/core/seq/oss/seq_oss_midi.c
@@ -612,9 +612,7 @@ send_midi_event(struct seq_oss_devinfo *dp, struct snd_seq_event *ev, struct seq
if (!dp->timer->running)
len = snd_seq_oss_timer_start(dp->timer);
if (ev->type == SNDRV_SEQ_EVENT_SYSEX) {
- if ((ev->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) == SNDRV_SEQ_EVENT_LENGTH_VARIABLE)
- snd_seq_oss_readq_puts(dp->readq, mdev->seq_device,
- ev->data.ext.ptr, ev->data.ext.len);
+ snd_seq_oss_readq_sysex(dp->readq, mdev->seq_device, ev);
} else {
len = snd_midi_event_decode(mdev->coder, msg, sizeof(msg), ev);
if (len > 0)
diff --git a/sound/core/seq/oss/seq_oss_readq.c b/sound/core/seq/oss/seq_oss_readq.c
index 046cb586fb2f..06b21226b4e7 100644
--- a/sound/core/seq/oss/seq_oss_readq.c
+++ b/sound/core/seq/oss/seq_oss_readq.c
@@ -118,6 +118,35 @@ snd_seq_oss_readq_puts(struct seq_oss_readq *q, int dev, unsigned char *data, in
}
/*
+ * put MIDI sysex bytes; the event buffer may be chained, thus it has
+ * to be expanded via snd_seq_dump_var_event().
+ */
+struct readq_sysex_ctx {
+ struct seq_oss_readq *readq;
+ int dev;
+};
+
+static int readq_dump_sysex(void *ptr, void *buf, int count)
+{
+ struct readq_sysex_ctx *ctx = ptr;
+
+ return snd_seq_oss_readq_puts(ctx->readq, ctx->dev, buf, count);
+}
+
+int snd_seq_oss_readq_sysex(struct seq_oss_readq *q, int dev,
+ struct snd_seq_event *ev)
+{
+ struct readq_sysex_ctx ctx = {
+ .readq = q,
+ .dev = dev
+ };
+
+ if ((ev->flags & SNDRV_SEQ_EVENT_LENGTH_MASK) != SNDRV_SEQ_EVENT_LENGTH_VARIABLE)
+ return 0;
+ return snd_seq_dump_var_event(ev, readq_dump_sysex, &ctx);
+}
+
+/*
* copy an event to input queue:
* return zero if enqueued
*/
diff --git a/sound/core/seq/oss/seq_oss_readq.h b/sound/core/seq/oss/seq_oss_readq.h
index f1463f1f449e..8d033ca2d23f 100644
--- a/sound/core/seq/oss/seq_oss_readq.h
+++ b/sound/core/seq/oss/seq_oss_readq.h
@@ -44,6 +44,8 @@ void snd_seq_oss_readq_delete(struct seq_oss_readq *q);
void snd_seq_oss_readq_clear(struct seq_oss_readq *readq);
unsigned int snd_seq_oss_readq_poll(struct seq_oss_readq *readq, struct file *file, poll_table *wait);
int snd_seq_oss_readq_puts(struct seq_oss_readq *readq, int dev, unsigned char *data, int len);
+int snd_seq_oss_readq_sysex(struct seq_oss_readq *q, int dev,
+ struct snd_seq_event *ev);
int snd_seq_oss_readq_put_event(struct seq_oss_readq *readq, union evrec *ev);
int snd_seq_oss_readq_put_timestamp(struct seq_oss_readq *readq, unsigned long curt, int seq_mode);
int snd_seq_oss_readq_pick(struct seq_oss_readq *q, union evrec *rec);