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Subject[RFC PATCH 7/7] sound: core: Avoid using timespec for struct snd_timer_tread
Date
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. Also add one struct compat_snd_timer_tread64_x86_32 to
handle 64bit time_t with 32bit alignment. That means we will set
tu->tread = 2 when user space has a 64bit time_t, then we will copy
to user with struct snd_timer_tread64. For x86_32 mode, we will set
tu->tread = 3 to copy struct compat_snd_timer_tread64_x86_32 for user.
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>
---
include/uapi/sound/asound.h | 11 ++-
sound/core/timer.c | 163 +++++++++++++++++++++++++++++++++++--------
2 files changed, 142 insertions(+), 32 deletions(-)

diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h
index 71bce52..ef738bf 100644
--- a/include/uapi/sound/asound.h
+++ b/include/uapi/sound/asound.h
@@ -760,7 +760,7 @@ struct snd_timer_status {

#define SNDRV_TIMER_IOCTL_PVERSION _IOR('T', 0x00, int)
#define SNDRV_TIMER_IOCTL_NEXT_DEVICE _IOWR('T', 0x01, struct snd_timer_id)
-#define SNDRV_TIMER_IOCTL_TREAD _IOW('T', 0x02, int)
+#define SNDRV_TIMER_IOCTL_TREAD_OLD _IOW('T', 0x02, int)
#define SNDRV_TIMER_IOCTL_GINFO _IOWR('T', 0x03, struct snd_timer_ginfo)
#define SNDRV_TIMER_IOCTL_GPARAMS _IOW('T', 0x04, struct snd_timer_gparams)
#define SNDRV_TIMER_IOCTL_GSTATUS _IOWR('T', 0x05, struct snd_timer_gstatus)
@@ -773,6 +773,15 @@ struct snd_timer_status {
#define SNDRV_TIMER_IOCTL_STOP _IO('T', 0xa1)
#define SNDRV_TIMER_IOCTL_CONTINUE _IO('T', 0xa2)
#define SNDRV_TIMER_IOCTL_PAUSE _IO('T', 0xa3)
+#define SNDRV_TIMER_IOCTL_TREAD64 _IOW('T', 0xa4, int)
+
+#if __BITS_PER_LONG == 64
+#define SNDRV_TIMER_IOCTL_TREAD SNDRV_TIMER_IOCTL_TREAD_OLD
+#else
+#define SNDRV_TIMER_IOCTL_TREAD ((sizeof(__kernel_long_t) > sizeof(time_t)) ? \
+ SNDRV_TIMER_IOCTL_TREAD_OLD : \
+ SNDRV_TIMER_IOCTL_TREAD64)
+#endif

struct snd_timer_read {
unsigned int resolution;
diff --git a/sound/core/timer.c b/sound/core/timer.c
index 376b7e6..c33a1be 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -58,6 +58,22 @@
MODULE_ALIAS_CHARDEV(CONFIG_SND_MAJOR, SNDRV_MINOR_TIMER);
MODULE_ALIAS("devname:snd/timer");

+struct snd_timer_tread64 {
+ int event;
+ u32 pad1;
+ struct { s64 tv_sec; s64 tv_nsec; } tstamp;
+ unsigned int val;
+ u32 pad2;
+};
+
+#ifdef IA32_EMULATION
+struct compat_snd_timer_tread64_x86_32 {
+ int event;
+ struct { s64 tv_sec; s64 tv_nsec; } tstamp;
+ unsigned int val;
+} __packed;
+#endif
+
struct snd_timer_user {
struct snd_timer_instance *timeri;
int tread; /* enhanced read with timestamps and events */
@@ -69,7 +85,7 @@ 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;
@@ -1262,7 +1278,7 @@ 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++;
@@ -1279,7 +1295,7 @@ 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 &&
@@ -1289,7 +1305,8 @@ 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.tv_sec = tstamp->tv_sec;
+ r1.tstamp.tv_nsec = tstamp->tv_nsec;
r1.val = resolution;
spin_lock_irqsave(&tu->qlock, flags);
snd_timer_user_append_to_tqueue(tu, &r1);
@@ -1311,7 +1328,7 @@ 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;

@@ -1332,7 +1349,8 @@ 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.tv_sec = tstamp.tv_sec;
+ r1.tstamp.tv_nsec = tstamp.tv_nsec;
r1.val = resolution;
snd_timer_user_append_to_tqueue(tu, &r1);
tu->last_resolution = resolution;
@@ -1346,14 +1364,16 @@ 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.tv_sec = tstamp.tv_sec;
+ r->tstamp.tv_nsec = tstamp.tv_nsec;
r->val += ticks;
append++;
goto __wake;
}
}
r1.event = SNDRV_TIMER_EVENT_TICK;
- r1.tstamp = timespec64_to_timespec(tstamp);
+ r1.tstamp.tv_sec = tstamp.tv_sec;
+ r1.tstamp.tv_nsec = tstamp.tv_nsec;
r1.val = ticks;
snd_timer_user_append_to_tqueue(tu, &r1);
append++;
@@ -1368,7 +1388,7 @@ 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);
@@ -1797,7 +1817,7 @@ 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;
@@ -1921,6 +1941,39 @@ static int snd_timer_user_pause(struct file *file)
return (err = snd_timer_pause(tu->timeri)) < 0 ? err : 0;
}

+static int snd_timer_user_tread(void __user *argp, struct snd_timer_user *tu,
+ unsigned int cmd)
+{
+ 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 __BITS_PER_LONG == 64
+ tu->tread = xarg ? 2 : 0;
+#ifdef IA32_EMULATION
+ tu->tread = xarg ? 3 : 0;
+#endif
+#else
+ if (cmd == SNDRV_TIMER_IOCTL_TREAD64)
+ tu->tread = xarg ? 2 : 0;
+ else
+ tu->tread = xarg ? 1 : 0;
+#endif
+
+ 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),
@@ -1941,23 +1994,9 @@ 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);
case SNDRV_TIMER_IOCTL_GINFO:
return snd_timer_user_ginfo(file, argp);
case SNDRV_TIMER_IOCTL_GPARAMS:
@@ -2021,7 +2060,25 @@ static ssize_t snd_timer_user_read(struct file *file, char __user *buffer,
int err = 0;

tu = file->private_data;
- unit = tu->tread ? sizeof(struct snd_timer_tread) : sizeof(struct snd_timer_read);
+ switch (tu->tread) {
+#ifdef IA32_EMULATION
+ case 3:
+ unit = sizeof(struct compat_snd_timer_tread64_x86_32);
+ break;
+#endif
+ case 2:
+ unit = sizeof(struct snd_timer_tread64);
+ break;
+ case 1:
+ unit = sizeof(struct snd_timer_tread);
+ break;
+ case 0:
+ unit = sizeof(struct snd_timer_read);
+ break;
+ default:
+ return -ENOTSUPP;
+ }
+
mutex_lock(&tu->ioctl_lock);
spin_lock_irq(&tu->qlock);
while ((long)count - result >= unit) {
@@ -2061,9 +2118,53 @@ static ssize_t snd_timer_user_read(struct file *file, char __user *buffer,
spin_unlock_irq(&tu->qlock);

if (tu->tread) {
- if (copy_to_user(buffer, &tu->tqueue[qhead],
- sizeof(struct snd_timer_tread)))
- err = -EFAULT;
+ struct snd_timer_tread64 *tread = &tu->tqueue[qhead];
+ struct snd_timer_tread tread32;
+#ifdef IA32_EMULATION
+ struct compat_snd_timer_tread64_x86_32 compat_tread64;
+#endif
+
+ switch (tu->tread) {
+#ifdef IA32_EMULATION
+ case 3:
+ memset(&compat_tread64, 0, sizeof(compat_tread64));
+ compat_tread64 = (struct compat_snd_timer_tread64_x86_32) {
+ .event = tread->event,
+ .tstamp = {
+ .tv_sec = tread->tstamp.tv_sec,
+ .tv_nsec = tread->tstamp.tv_nsec,
+ },
+ .val = tread->val,
+ };
+
+ if (copy_to_user(buffer, &compat_tread64,
+ sizeof(compat_tread64)))
+ err = -EFAULT;
+ break;
+#endif
+ case 2:
+ if (copy_to_user(buffer, tread,
+ sizeof(struct snd_timer_tread64)))
+ err = -EFAULT;
+ break;
+ case 1:
+ memset(&tread32, 0, sizeof(tread32));
+ tread32 = (struct snd_timer_tread) {
+ .event = tread->event,
+ .tstamp = {
+ .tv_sec = tread->tstamp.tv_sec,
+ .tv_nsec = tread->tstamp.tv_nsec,
+ },
+ .val = tread->val,
+ };
+
+ if (copy_to_user(buffer, &tread32, sizeof(tread32)))
+ err = -EFAULT;
+ break;
+ default:
+ err = -ENOTSUPP;
+ break;
+ }
} else {
if (copy_to_user(buffer, &tu->queue[qhead],
sizeof(struct snd_timer_read)))
--
1.7.9.5
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