ALSA: Avoid using timespec for struct snd_timer_tread

The struct snd_timer_tread will use 'timespec' type variables to record
timestamp, which is not year 2038 safe on 32bits system.

Since the struct snd_timer_tread is passed through read() rather than
ioctl(), and the read syscall has no command number that lets us pick
between the 32-bit or 64-bit version of this structure.

Thus we introduced one new command SNDRV_TIMER_IOCTL_TREAD64 and new
struct snd_timer_tread64 replacing timespec with s64 type to handle
64bit time_t. That means we will set tu->tread = TREAD_FORMAT_64BIT
when user space has a 64bit time_t, then we will copy to user with
struct snd_timer_tread64. Otherwise we will use 32bit time_t variables
when copying to user.

Moreover this patch replaces timespec type with timespec64 type and
related y2038 safe APIs.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

1 files changed, 114 insertions, 36 deletions

diff --git a/sound/core/timer.c b/sound/core/timer.c
index d2f69039f941..4cfd8e691903 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -44,6 +44,28 @@ MODULE_PARM_DESC(timer_tstamp_monotonic, "Use posix monotonic clock source for t
 MODULE_ALIAS_CHARDEV(CONFIG_SND_MAJOR, SNDRV_MINOR_TIMER);
 MODULE_ALIAS("devname:snd/timer");
 
+enum timer_tread_format {
+	TREAD_FORMAT_NONE = 0,
+	TREAD_FORMAT_TIME64,
+	TREAD_FORMAT_TIME32,
+};
+
+struct snd_timer_tread32 {
+	int event;
+	s32 tstamp_sec;
+	s32 tstamp_nsec;
+	unsigned int val;
+};
+
+struct snd_timer_tread64 {
+	int event;
+	u8 pad1[4];
+	s64 tstamp_sec;
+	s64 tstamp_nsec;
+	unsigned int val;
+	u8 pad2[4];
+};
+
 struct snd_timer_user {
 	struct snd_timer_instance *timeri;
 	int tread;		/* enhanced read with timestamps and events */
@@ -55,7 +77,7 @@ struct snd_timer_user {
 	int queue_size;
 	bool disconnected;
 	struct snd_timer_read *queue;
-	struct snd_timer_tread *tqueue;
+	struct snd_timer_tread64 *tqueue;
 	spinlock_t qlock;
 	unsigned long last_resolution;
 	unsigned int filter;
@@ -1329,7 +1351,7 @@ static void snd_timer_user_interrupt(struct snd_timer_instance *timeri,
 }
 
 static void snd_timer_user_append_to_tqueue(struct snd_timer_user *tu,
-					    struct snd_timer_tread *tread)
+					    struct snd_timer_tread64 *tread)
 {
 	if (tu->qused >= tu->queue_size) {
 		tu->overrun++;
@@ -1346,7 +1368,7 @@ static void snd_timer_user_ccallback(struct snd_timer_instance *timeri,
 				     unsigned long resolution)
 {
 	struct snd_timer_user *tu = timeri->callback_data;
-	struct snd_timer_tread r1;
+	struct snd_timer_tread64 r1;
 	unsigned long flags;
 
 	if (event >= SNDRV_TIMER_EVENT_START &&
@@ -1356,7 +1378,8 @@ static void snd_timer_user_ccallback(struct snd_timer_instance *timeri,
 		return;
 	memset(&r1, 0, sizeof(r1));
 	r1.event = event;
-	r1.tstamp = timespec64_to_timespec(*tstamp);
+	r1.tstamp_sec = tstamp->tv_sec;
+	r1.tstamp_nsec = tstamp->tv_nsec;
 	r1.val = resolution;
 	spin_lock_irqsave(&tu->qlock, flags);
 	snd_timer_user_append_to_tqueue(tu, &r1);
@@ -1378,7 +1401,7 @@ static void snd_timer_user_tinterrupt(struct snd_timer_instance *timeri,
 				      unsigned long ticks)
 {
 	struct snd_timer_user *tu = timeri->callback_data;
-	struct snd_timer_tread *r, r1;
+	struct snd_timer_tread64 *r, r1;
 	struct timespec64 tstamp;
 	int prev, append = 0;
 
@@ -1399,7 +1422,8 @@ static void snd_timer_user_tinterrupt(struct snd_timer_instance *timeri,
 	if ((tu->filter & (1 << SNDRV_TIMER_EVENT_RESOLUTION)) &&
 	    tu->last_resolution != resolution) {
 		r1.event = SNDRV_TIMER_EVENT_RESOLUTION;
-		r1.tstamp = timespec64_to_timespec(tstamp);
+		r1.tstamp_sec = tstamp.tv_sec;
+		r1.tstamp_nsec = tstamp.tv_nsec;
 		r1.val = resolution;
 		snd_timer_user_append_to_tqueue(tu, &r1);
 		tu->last_resolution = resolution;
@@ -1413,14 +1437,16 @@ static void snd_timer_user_tinterrupt(struct snd_timer_instance *timeri,
 		prev = tu->qtail == 0 ? tu->queue_size - 1 : tu->qtail - 1;
 		r = &tu->tqueue[prev];
 		if (r->event == SNDRV_TIMER_EVENT_TICK) {
-			r->tstamp = timespec64_to_timespec(tstamp);
+			r->tstamp_sec = tstamp.tv_sec;
+			r->tstamp_nsec = tstamp.tv_nsec;
 			r->val += ticks;
 			append++;
 			goto __wake;
 		}
 	}
 	r1.event = SNDRV_TIMER_EVENT_TICK;
-	r1.tstamp = timespec64_to_timespec(tstamp);
+	r1.tstamp_sec = tstamp.tv_sec;
+	r1.tstamp_nsec = tstamp.tv_nsec;
 	r1.val = ticks;
 	snd_timer_user_append_to_tqueue(tu, &r1);
 	append++;
@@ -1435,7 +1461,7 @@ static void snd_timer_user_tinterrupt(struct snd_timer_instance *timeri,
 static int realloc_user_queue(struct snd_timer_user *tu, int size)
 {
 	struct snd_timer_read *queue = NULL;
-	struct snd_timer_tread *tqueue = NULL;
+	struct snd_timer_tread64 *tqueue = NULL;
 
 	if (tu->tread) {
 		tqueue = kcalloc(size, sizeof(*tqueue), GFP_KERNEL);
@@ -1874,11 +1900,11 @@ static int snd_timer_user_params(struct file *file,
 	tu->qhead = tu->qtail = tu->qused = 0;
 	if (tu->timeri->flags & SNDRV_TIMER_IFLG_EARLY_EVENT) {
 		if (tu->tread) {
-			struct snd_timer_tread tread;
+			struct snd_timer_tread64 tread;
 			memset(&tread, 0, sizeof(tread));
 			tread.event = SNDRV_TIMER_EVENT_EARLY;
-			tread.tstamp.tv_sec = 0;
-			tread.tstamp.tv_nsec = 0;
+			tread.tstamp_sec = 0;
+			tread.tstamp_nsec = 0;
 			tread.val = 0;
 			snd_timer_user_append_to_tqueue(tu, &tread);
 		} else {
@@ -2008,6 +2034,36 @@ static int snd_timer_user_pause(struct file *file)
 	return 0;
 }
 
+static int snd_timer_user_tread(void __user *argp, struct snd_timer_user *tu,
+				unsigned int cmd, bool compat)
+{
+	int __user *p = argp;
+	int xarg, old_tread;
+
+	if (tu->timeri)	/* too late */
+		return -EBUSY;
+	if (get_user(xarg, p))
+		return -EFAULT;
+
+	old_tread = tu->tread;
+
+	if (!xarg)
+		tu->tread = TREAD_FORMAT_NONE;
+	else if (cmd == SNDRV_TIMER_IOCTL_TREAD64 ||
+		 (IS_ENABLED(CONFIG_64BIT) && !compat))
+		tu->tread = TREAD_FORMAT_TIME64;
+	else
+		tu->tread = TREAD_FORMAT_TIME32;
+
+	if (tu->tread != old_tread &&
+	    realloc_user_queue(tu, tu->queue_size) < 0) {
+		tu->tread = old_tread;
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
 enum {
 	SNDRV_TIMER_IOCTL_START_OLD = _IO('T', 0x20),
 	SNDRV_TIMER_IOCTL_STOP_OLD = _IO('T', 0x21),
@@ -2016,7 +2072,7 @@ enum {
 };
 
 static long __snd_timer_user_ioctl(struct file *file, unsigned int cmd,
-				 unsigned long arg)
+				 unsigned long arg, bool compat)
 {
 	struct snd_timer_user *tu;
 	void __user *argp = (void __user *)arg;
@@ -2028,23 +2084,9 @@ static long __snd_timer_user_ioctl(struct file *file, unsigned int cmd,
 		return put_user(SNDRV_TIMER_VERSION, p) ? -EFAULT : 0;
 	case SNDRV_TIMER_IOCTL_NEXT_DEVICE:
 		return snd_timer_user_next_device(argp);
-	case SNDRV_TIMER_IOCTL_TREAD:
-	{
-		int xarg, old_tread;
-
-		if (tu->timeri)	/* too late */
-			return -EBUSY;
-		if (get_user(xarg, p))
-			return -EFAULT;
-		old_tread = tu->tread;
-		tu->tread = xarg ? 1 : 0;
-		if (tu->tread != old_tread &&
-		    realloc_user_queue(tu, tu->queue_size) < 0) {
-			tu->tread = old_tread;
-			return -ENOMEM;
-		}
-		return 0;
-	}
+	case SNDRV_TIMER_IOCTL_TREAD_OLD:
+	case SNDRV_TIMER_IOCTL_TREAD64:
+		return snd_timer_user_tread(argp, tu, cmd, compat);
 	case SNDRV_TIMER_IOCTL_GINFO:
 		return snd_timer_user_ginfo(file, argp);
 	case SNDRV_TIMER_IOCTL_GPARAMS:
@@ -2084,7 +2126,7 @@ static long snd_timer_user_ioctl(struct file *file, unsigned int cmd,
 	long ret;
 
 	mutex_lock(&tu->ioctl_lock);
-	ret = __snd_timer_user_ioctl(file, cmd, arg);
+	ret = __snd_timer_user_ioctl(file, cmd, arg, false);
 	mutex_unlock(&tu->ioctl_lock);
 	return ret;
 }
@@ -2100,13 +2142,29 @@ static int snd_timer_user_fasync(int fd, struct file * file, int on)
 static ssize_t snd_timer_user_read(struct file *file, char __user *buffer,
 				   size_t count, loff_t *offset)
 {
+	struct snd_timer_tread64 *tread;
+	struct snd_timer_tread32 tread32;
 	struct snd_timer_user *tu;
 	long result = 0, unit;
 	int qhead;
 	int err = 0;
 
 	tu = file->private_data;
-	unit = tu->tread ? sizeof(struct snd_timer_tread) : sizeof(struct snd_timer_read);
+	switch (tu->tread) {
+	case TREAD_FORMAT_TIME64:
+		unit = sizeof(struct snd_timer_tread64);
+		break;
+	case TREAD_FORMAT_TIME32:
+		unit = sizeof(struct snd_timer_tread32);
+		break;
+	case TREAD_FORMAT_NONE:
+		unit = sizeof(struct snd_timer_read);
+		break;
+	default:
+		WARN_ONCE(1, "Corrupt snd_timer_user\n");
+		return -ENOTSUPP;
+	}
+
 	mutex_lock(&tu->ioctl_lock);
 	spin_lock_irq(&tu->qlock);
 	while ((long)count - result >= unit) {
@@ -2145,14 +2203,34 @@ static ssize_t snd_timer_user_read(struct file *file, char __user *buffer,
 		tu->qused--;
 		spin_unlock_irq(&tu->qlock);
 
-		if (tu->tread) {
-			if (copy_to_user(buffer, &tu->tqueue[qhead],
-					 sizeof(struct snd_timer_tread)))
+		tread = &tu->tqueue[qhead];
+
+		switch (tu->tread) {
+		case TREAD_FORMAT_TIME64:
+			if (copy_to_user(buffer, tread,
+					 sizeof(struct snd_timer_tread64)))
 				err = -EFAULT;
-		} else {
+			break;
+		case TREAD_FORMAT_TIME32:
+			memset(&tread32, 0, sizeof(tread32));
+			tread32 = (struct snd_timer_tread32) {
+				.event = tread->event,
+				.tstamp_sec = tread->tstamp_sec,
+				.tstamp_sec = tread->tstamp_nsec,
+				.val = tread->val,
+			};
+
+			if (copy_to_user(buffer, &tread32, sizeof(tread32)))
+				err = -EFAULT;
+			break;
+		case TREAD_FORMAT_NONE:
 			if (copy_to_user(buffer, &tu->queue[qhead],
 					 sizeof(struct snd_timer_read)))
 				err = -EFAULT;
+			break;
+		default:
+			err = -ENOTSUPP;
+			break;
 		}
 
 		spin_lock_irq(&tu->qlock);