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ALSA: rawmidi: Access runtime->avail always in spinlock 

The runtime->avail field may be accessed concurrently while some
places refer to it without taking the runtime->lock spinlock, as
detected by KCSAN.  Usually this isn't a big problem, but for
consistency and safety, we should take the spinlock at each place
referencing this field.

Reported-by: syzbot+a23a6f1215c84756577c@syzkaller.appspotmail.com
Reported-by: syzbot+3d367d1df1d2b67f5c19@syzkaller.appspotmail.com
Link: https://lore.kernel.org/r/20201206083527.21163-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Takashi Iwai 2020-12-06 09:35:27 +01:00
parent 4ebd470370
commit 88a06d6fd6
1 changed files with 35 additions and 14 deletions
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49
sound/core/rawmidi.c
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@ -95,11 +95,21 @@ static inline unsigned short snd_rawmidi_file_flags(struct file *file)
}
}
static inline int snd_rawmidi_ready(struct snd_rawmidi_substream *substream)
static inline bool __snd_rawmidi_ready(struct snd_rawmidi_runtime *runtime)
{
return runtime->avail >= runtime->avail_min;
}
static bool snd_rawmidi_ready(struct snd_rawmidi_substream *substream)
{
struct snd_rawmidi_runtime *runtime = substream->runtime;
unsigned long flags;
bool ready;
return runtime->avail >= runtime->avail_min;
spin_lock_irqsave(&runtime->lock, flags);
ready = __snd_rawmidi_ready(runtime);
spin_unlock_irqrestore(&runtime->lock, flags);
return ready;
}
static inline int snd_rawmidi_ready_append(struct snd_rawmidi_substream *substream,
@ -1019,7 +1029,7 @@ int snd_rawmidi_receive(struct snd_rawmidi_substream *substream,
if (result > 0) {
if (runtime->event)
schedule_work(&runtime->event_work);
else if (snd_rawmidi_ready(substream))
else if (__snd_rawmidi_ready(runtime))
wake_up(&runtime->sleep);
}
spin_unlock_irqrestore(&runtime->lock, flags);
@ -1098,7 +1108,7 @@ static ssize_t snd_rawmidi_read(struct file *file, char __user *buf, size_t coun
result = 0;
while (count > 0) {
spin_lock_irq(&runtime->lock);
while (!snd_rawmidi_ready(substream)) {
while (!__snd_rawmidi_ready(runtime)) {
wait_queue_entry_t wait;
if ((file->f_flags & O_NONBLOCK) != 0 || result > 0) {
@ -1115,9 +1125,11 @@ static ssize_t snd_rawmidi_read(struct file *file, char __user *buf, size_t coun
return -ENODEV;
if (signal_pending(current))
return result > 0 ? result : -ERESTARTSYS;
if (!runtime->avail)
return result > 0 ? result : -EIO;
spin_lock_irq(&runtime->lock);
if (!runtime->avail) {
spin_unlock_irq(&runtime->lock);
return result > 0 ? result : -EIO;
}
}
spin_unlock_irq(&runtime->lock);
count1 = snd_rawmidi_kernel_read1(substream,
@ -1255,7 +1267,7 @@ int __snd_rawmidi_transmit_ack(struct snd_rawmidi_substream *substream, int coun
runtime->avail += count;
substream->bytes += count;
if (count > 0) {
if (runtime->drain || snd_rawmidi_ready(substream))
if (runtime->drain || __snd_rawmidi_ready(runtime))
wake_up(&runtime->sleep);
}
return count;
@ -1444,9 +1456,11 @@ static ssize_t snd_rawmidi_write(struct file *file, const char __user *buf,
return -ENODEV;
if (signal_pending(current))
return result > 0 ? result : -ERESTARTSYS;
if (!runtime->avail && !timeout)
return result > 0 ? result : -EIO;
spin_lock_irq(&runtime->lock);
if (!runtime->avail && !timeout) {
spin_unlock_irq(&runtime->lock);
return result > 0 ? result : -EIO;
}
}
spin_unlock_irq(&runtime->lock);
count1 = snd_rawmidi_kernel_write1(substream, buf, NULL, count);
@ -1526,6 +1540,7 @@ static void snd_rawmidi_proc_info_read(struct snd_info_entry *entry,
struct snd_rawmidi *rmidi;
struct snd_rawmidi_substream *substream;
struct snd_rawmidi_runtime *runtime;
unsigned long buffer_size, avail, xruns;
rmidi = entry->private_data;
snd_iprintf(buffer, "%s\n\n", rmidi->name);
@ -1544,13 +1559,16 @@ static void snd_rawmidi_proc_info_read(struct snd_info_entry *entry,
" Owner PID : %d\n",
pid_vnr(substream->pid));
runtime = substream->runtime;
spin_lock_irq(&runtime->lock);
buffer_size = runtime->buffer_size;
avail = runtime->avail;
spin_unlock_irq(&runtime->lock);
snd_iprintf(buffer,
" Mode : %s\n"
" Buffer size : %lu\n"
" Avail : %lu\n",
runtime->oss ? "OSS compatible" : "native",
(unsigned long) runtime->buffer_size,
(unsigned long) runtime->avail);
buffer_size, avail);
}
}
}
@ -1568,13 +1586,16 @@ static void snd_rawmidi_proc_info_read(struct snd_info_entry *entry,
" Owner PID : %d\n",
pid_vnr(substream->pid));
runtime = substream->runtime;
spin_lock_irq(&runtime->lock);
buffer_size = runtime->buffer_size;
avail = runtime->avail;
xruns = runtime->xruns;
spin_unlock_irq(&runtime->lock);
snd_iprintf(buffer,
" Buffer size : %lu\n"
" Avail : %lu\n"
" Overruns : %lu\n",
(unsigned long) runtime->buffer_size,
(unsigned long) runtime->avail,
(unsigned long) runtime->xruns);
buffer_size, avail, xruns);
}
}
}