ALSA: info - Check file position validity in common layer

Check the validity of the file position in the common info layer before
calling read or write callbacks in assumption that entry->size is set up
properly to indicate the max file size.

Removed the redundant checks from the callbacks as well.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

4 files changed, 29 insertions, 62 deletions

diff --git a/sound/pci/cs4281.c b/sound/pci/cs4281.c
index b0bba2e86b12..6772070ed492 100644
--- a/sound/pci/cs4281.c
+++ b/sound/pci/cs4281.c
@@ -1144,17 +1144,11 @@ static ssize_t snd_cs4281_BA0_read(struct snd_info_entry *entry,
 				   struct file *file, char __user *buf,
 				   size_t count, loff_t pos)
 {
-	long size;
 	struct cs4281 *chip = entry->private_data;
 	
-	size = count;
-	if (pos + size > CS4281_BA0_SIZE)
-		size = (long)CS4281_BA0_SIZE - pos;
-	if (size > 0) {
-		if (copy_to_user_fromio(buf, chip->ba0 + pos, size))
-			return -EFAULT;
-	}
-	return size;
+	if (copy_to_user_fromio(buf, chip->ba0 + pos, count))
+		return -EFAULT;
+	return count;
 }
 
 static ssize_t snd_cs4281_BA1_read(struct snd_info_entry *entry,
@@ -1162,17 +1156,11 @@ static ssize_t snd_cs4281_BA1_read(struct snd_info_entry *entry,
 				   struct file *file, char __user *buf,
 				   size_t count, loff_t pos)
 {
-	long size;
 	struct cs4281 *chip = entry->private_data;
 	
-	size = count;
-	if (pos + size > CS4281_BA1_SIZE)
-		size = (long)CS4281_BA1_SIZE - pos;
-	if (size > 0) {
-		if (copy_to_user_fromio(buf, chip->ba1 + pos, size))
-			return -EFAULT;
-	}
-	return size;
+	if (copy_to_user_fromio(buf, chip->ba1 + pos, count))
+		return -EFAULT;
+	return count;
 }
 
 static struct snd_info_entry_ops snd_cs4281_proc_ops_BA0 = {
diff --git a/sound/pci/cs46xx/cs46xx_lib.c b/sound/pci/cs46xx/cs46xx_lib.c
index 08117b142381..aad37082cb6e 100644
--- a/sound/pci/cs46xx/cs46xx_lib.c
+++ b/sound/pci/cs46xx/cs46xx_lib.c
@@ -2662,17 +2662,11 @@ static ssize_t snd_cs46xx_io_read(struct snd_info_entry *entry,
 				  struct file *file, char __user *buf,
 				  size_t count, loff_t pos)
 {
-	long size;
 	struct snd_cs46xx_region *region = entry->private_data;
 	
-	size = count;
-	if (pos + (size_t)size > region->size)
-		size = region->size - pos;
-	if (size > 0) {
-		if (copy_to_user_fromio(buf, region->remap_addr + pos, size))
-			return -EFAULT;
-	}
-	return size;
+	if (copy_to_user_fromio(buf, region->remap_addr + pos, count))
+		return -EFAULT;
+	return count;
 }
 
 static struct snd_info_entry_ops snd_cs46xx_proc_io_ops = {
diff --git a/sound/pci/emu10k1/emuproc.c b/sound/pci/emu10k1/emuproc.c
index 347b2415db59..bc38dd4d071f 100644
--- a/sound/pci/emu10k1/emuproc.c
+++ b/sound/pci/emu10k1/emuproc.c
@@ -346,10 +346,12 @@ static ssize_t snd_emu10k1_fx8010_read(struct snd_info_entry *entry,
 				       struct file *file, char __user *buf,
 				       size_t count, loff_t pos)
 {
-	long size;
 	struct snd_emu10k1 *emu = entry->private_data;
 	unsigned int offset;
 	int tram_addr = 0;
+	unsigned int *tmp;
+	long res;
+	unsigned int idx;
 	
 	if (!strcmp(entry->name, "fx8010_tram_addr")) {
 		offset = TANKMEMADDRREGBASE;
@@ -361,30 +363,25 @@ static ssize_t snd_emu10k1_fx8010_read(struct snd_info_entry *entry,
 	} else {
 		offset = emu->audigy ? A_FXGPREGBASE : FXGPREGBASE;
 	}
-	size = count;
-	if (pos + size > entry->size)
-		size = (long)entry->size - pos;
-	if (size > 0) {
-		unsigned int *tmp;
-		long res;
-		unsigned int idx;
-		if ((tmp = kmalloc(size + 8, GFP_KERNEL)) == NULL)
-			return -ENOMEM;
-		for (idx = 0; idx < ((pos & 3) + size + 3) >> 2; idx++)
-			if (tram_addr && emu->audigy) {
-				tmp[idx] = snd_emu10k1_ptr_read(emu, offset + idx + (pos >> 2), 0) >> 11;
-				tmp[idx] |= snd_emu10k1_ptr_read(emu, 0x100 + idx + (pos >> 2), 0) << 20;
-			} else 
-				tmp[idx] = snd_emu10k1_ptr_read(emu, offset + idx + (pos >> 2), 0);
-		if (copy_to_user(buf, ((char *)tmp) + (pos & 3), size))
-			res = -EFAULT;
-		else {
-			res = size;
+
+	tmp = kmalloc(count + 8, GFP_KERNEL);
+	if (!tmp)
+		return -ENOMEM;
+	for (idx = 0; idx < ((pos & 3) + count + 3) >> 2; idx++) {
+		unsigned int val;
+		val = snd_emu10k1_ptr_read(emu, offset + idx + (pos >> 2), 0);
+		if (tram_addr && emu->audigy) {
+			val >>= 11;
+			val |= snd_emu10k1_ptr_read(emu, 0x100 + idx + (pos >> 2), 0) << 20;
 		}
-		kfree(tmp);
-		return res;
+		tmp[idx] = val;
 	}
-	return 0;
+	if (copy_to_user(buf, ((char *)tmp) + (pos & 3), count))
+		res = -EFAULT;
+	else
+		res = count;
+	kfree(tmp);
+	return res;
 }
 
 static void snd_emu10k1_proc_voices_read(struct snd_info_entry *entry, 
diff --git a/sound/pci/mixart/mixart.c b/sound/pci/mixart/mixart.c
index b5df78bcc25b..be95e005c81d 100644
--- a/sound/pci/mixart/mixart.c
+++ b/sound/pci/mixart/mixart.c
@@ -1161,13 +1161,7 @@ static ssize_t snd_mixart_BA0_read(struct snd_info_entry *entry,
 				   size_t count, loff_t pos)
 {
 	struct mixart_mgr *mgr = entry->private_data;
-	unsigned long maxsize;
 
-	if (pos >= MIXART_BA0_SIZE)
-		return 0;
-	maxsize = MIXART_BA0_SIZE - pos;
-	if (count > maxsize)
-		count = maxsize;
 	count = count & ~3; /* make sure the read size is a multiple of 4 bytes */
 	if (copy_to_user_fromio(buf, MIXART_MEM(mgr, pos), count))
 		return -EFAULT;
@@ -1183,13 +1177,7 @@ static ssize_t snd_mixart_BA1_read(struct snd_info_entry *entry,
 				   size_t count, loff_t pos)
 {
 	struct mixart_mgr *mgr = entry->private_data;
-	unsigned long maxsize;
 
-	if (pos > MIXART_BA1_SIZE)
-		return 0;
-	maxsize = MIXART_BA1_SIZE - pos;
-	if (count > maxsize)
-		count = maxsize;
 	count = count & ~3; /* make sure the read size is a multiple of 4 bytes */
 	if (copy_to_user_fromio(buf, MIXART_REG(mgr, pos), count))
 		return -EFAULT;