ALSA: timer: fix gparams ioctl compatibility for different architectures

'struct snd_timer_gparams' includes some members with 'unsigned long',
therefore its size differs depending on data models of architecture. As
a result, x86/x32 applications fail to execute ioctl(2) with
SNDRV_TIMER_GPARAMS command on x86_64 machine.

This commit fixes this bug by adding a pair of structure and ioctl
command for the compatibility.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 42 insertions, 8 deletions

diff --git a/sound/core/timer.c b/sound/core/timer.c
index aa1b15c155d1..ea4d999113ef 100644
--- a/sound/core/timer.c
+++ b/sound/core/timer.c
@@ -1502,17 +1502,13 @@ static int snd_timer_user_ginfo(struct file *file,
         return err;
 }
 
-static int snd_timer_user_gparams(struct file *file,
-                                  struct snd_timer_gparams __user *_gparams)
+static int timer_set_gparams(struct snd_timer_gparams *gparams)
 {
-        struct snd_timer_gparams gparams;
         struct snd_timer *t;
         int err;
 
-        if (copy_from_user(&gparams, _gparams, sizeof(gparams)))
-                return -EFAULT;
         mutex_lock(&register_mutex);
-        t = snd_timer_find(&gparams.tid);
+        t = snd_timer_find(&gparams->tid);
         if (!t) {
                 err = -ENODEV;
                 goto _error;
@@ -1525,12 +1521,22 @@ static int snd_timer_user_gparams(struct file *file,
                 err = -ENOSYS;
                 goto _error;
         }
-        err = t->hw.set_period(t, gparams.period_num, gparams.period_den);
+        err = t->hw.set_period(t, gparams->period_num, gparams->period_den);
 _error:
         mutex_unlock(&register_mutex);
         return err;
 }
 
+static int snd_timer_user_gparams(struct file *file,
+                                  struct snd_timer_gparams __user *_gparams)
+{
+        struct snd_timer_gparams gparams;
+
+        if (copy_from_user(&gparams, _gparams, sizeof(gparams)))
+                return -EFAULT;
+        return timer_set_gparams(&gparams);
+}
+
 static int snd_timer_user_gstatus(struct file *file,
                                   struct snd_timer_gstatus __user *_gstatus)
 {
diff --git a/sound/core/timer_compat.c b/sound/core/timer_compat.c
index 2e908225d754..6a437eb66115 100644
--- a/sound/core/timer_compat.c
+++ b/sound/core/timer_compat.c
@@ -22,6 +22,19 @@
 
 #include <linux/compat.h>
 
+/*
+ * ILP32/LP64 has different size for 'long' type. Additionally, the size
+ * of storage alignment differs depending on architectures. Here, '__packed'
+ * qualifier is used so that the size of this structure is multiple of 4 and
+ * it fits to any architectures with 32 bit storage alignment.
+ */
+struct snd_timer_gparams32 {
+        struct snd_timer_id tid;
+        u32 period_num;
+        u32 period_den;
+        unsigned char reserved[32];
+} __packed;
+
 struct snd_timer_info32 {
         u32 flags;
         s32 card;
@@ -32,6 +45,19 @@ struct snd_timer_info32 {
         unsigned char reserved[64];
 };
 
+static int snd_timer_user_gparams_compat(struct file *file,
+                                        struct snd_timer_gparams32 __user *user)
+{
+        struct snd_timer_gparams gparams;
+
+        if (copy_from_user(&gparams.tid, &user->tid, sizeof(gparams.tid)) ||
+            get_user(gparams.period_num, &user->period_num) ||
+            get_user(gparams.period_den, &user->period_den))
+                return -EFAULT;
+
+        return timer_set_gparams(&gparams);
+}
+
 static int snd_timer_user_info_compat(struct file *file,
                                       struct snd_timer_info32 __user *_info)
 {
@@ -99,6 +125,7 @@ static int snd_timer_user_status_compat(struct file *file,
  */
 
 enum {
+        SNDRV_TIMER_IOCTL_GPARAMS32 = _IOW('T', 0x04, struct snd_timer_gparams32),
         SNDRV_TIMER_IOCTL_INFO32 = _IOR('T', 0x11, struct snd_timer_info32),
         SNDRV_TIMER_IOCTL_STATUS32 = _IOW('T', 0x14, struct snd_timer_status32),
 #ifdef CONFIG_X86_X32
@@ -114,7 +141,6 @@ static long snd_timer_user_ioctl_compat(struct file *file, unsigned int cmd, uns
         case SNDRV_TIMER_IOCTL_PVERSION:
         case SNDRV_TIMER_IOCTL_TREAD:
         case SNDRV_TIMER_IOCTL_GINFO:
-        case SNDRV_TIMER_IOCTL_GPARAMS:
         case SNDRV_TIMER_IOCTL_GSTATUS:
         case SNDRV_TIMER_IOCTL_SELECT:
         case SNDRV_TIMER_IOCTL_PARAMS:
@@ -128,6 +154,8 @@ static long snd_timer_user_ioctl_compat(struct file *file, unsigned int cmd, uns
         case SNDRV_TIMER_IOCTL_PAUSE_OLD:
         case SNDRV_TIMER_IOCTL_NEXT_DEVICE:
                 return snd_timer_user_ioctl(file, cmd, (unsigned long)argp);
+        case SNDRV_TIMER_IOCTL_GPARAMS32:
+                return snd_timer_user_gparams_compat(file, argp);
         case SNDRV_TIMER_IOCTL_INFO32:
                 return snd_timer_user_info_compat(file, argp);
         case SNDRV_TIMER_IOCTL_STATUS32: