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>

7 files changed, 60 insertions, 105 deletions

diff --git a/sound/core/info.c b/sound/core/info.c
index ff968be81678..f90a6fd43fb4 100644
--- a/sound/core/info.c
+++ b/sound/core/info.c
@@ -232,10 +232,15 @@ static ssize_t snd_info_entry_read(struct file *file, char __user *buffer,
                         return -EFAULT;
                 break;
         case SNDRV_INFO_CONTENT_DATA:
-                if (entry->c.ops->read)
+                if (pos >= entry->size)
+                        return 0;
+                if (entry->c.ops->read) {
+                        size = entry->size - pos;
+                        size = min(count, size);
                         size = entry->c.ops->read(entry,
                                                   data->file_private_data,
-                                                  file, buffer, count, pos);
+                                                  file, buffer, size, pos);
+                }
                 break;
         }
         if ((ssize_t) size > 0)
@@ -282,10 +287,13 @@ static ssize_t snd_info_entry_write(struct file *file, const char __user *buffer
                 size = count;
                 break;
         case SNDRV_INFO_CONTENT_DATA:
-                if (entry->c.ops->write)
+                if (entry->c.ops->write && count > 0) {
+                        size_t maxsize = entry->size - pos;
+                        count = min(count, maxsize);
                         size = entry->c.ops->write(entry,
                                                    data->file_private_data,
                                                    file, buffer, count, pos);
+                }
                 break;
         }
         if ((ssize_t) size > 0)
diff --git a/sound/drivers/opl4/opl4_proc.c b/sound/drivers/opl4/opl4_proc.c
index eb72814dfd5f..210b89de06d7 100644
--- a/sound/drivers/opl4/opl4_proc.c
+++ b/sound/drivers/opl4/opl4_proc.c
@@ -55,25 +55,18 @@ static ssize_t snd_opl4_mem_proc_read(struct snd_info_entry *entry,
                                       size_t count, loff_t pos)
 {
         struct snd_opl4 *opl4 = entry->private_data;
-        long size;
         char* buf;
 
-        size = count;
-        if (pos + size > entry->size)
-                size = entry->size - pos;
-        if (size > 0) {
-                buf = vmalloc(size);
-                if (!buf)
-                        return -ENOMEM;
-                snd_opl4_read_memory(opl4, buf, pos, size);
-                if (copy_to_user(_buf, buf, size)) {
-                        vfree(buf);
-                        return -EFAULT;
-                }
+        buf = vmalloc(count);
+        if (!buf)
+                return -ENOMEM;
+        snd_opl4_read_memory(opl4, buf, pos, count);
+        if (copy_to_user(_buf, buf, count)) {
                 vfree(buf);
-                return size;
+                return -EFAULT;
         }
-        return 0;
+        vfree(buf);
+        return count;
 }
 
 static ssize_t snd_opl4_mem_proc_write(struct snd_info_entry *entry,
@@ -83,25 +76,18 @@ static ssize_t snd_opl4_mem_proc_write(struct snd_info_entry *entry,
                                        size_t count, size_t pos)
 {
         struct snd_opl4 *opl4 = entry->private_data;
-        long size;
         char *buf;
 
-        size = count;
-        if (pos + size > entry->size)
-                size = entry->size - pos;
-        if (size > 0) {
-                buf = vmalloc(size);
-                if (!buf)
-                        return -ENOMEM;
-                if (copy_from_user(buf, _buf, size)) {
-                        vfree(buf);
-                        return -EFAULT;
-                }
-                snd_opl4_write_memory(opl4, buf, pos, size);
+        buf = vmalloc(count);
+        if (!buf)
+                return -ENOMEM;
+        if (copy_from_user(buf, _buf, count)) {
                 vfree(buf);
-                return size;
+                return -EFAULT;
         }
-        return 0;
+        snd_opl4_write_memory(opl4, buf, pos, count);
+        vfree(buf);
+        return count;
 }
 
 static loff_t snd_opl4_mem_proc_llseek(struct snd_info_entry *entry,
diff --git a/sound/isa/gus/gus_mem_proc.c b/sound/isa/gus/gus_mem_proc.c
index b2d2dba6c860..faa2bec8f6b6 100644
--- a/sound/isa/gus/gus_mem_proc.c
+++ b/sound/isa/gus/gus_mem_proc.c
@@ -36,20 +36,14 @@ static ssize_t snd_gf1_mem_proc_dump(struct snd_info_entry *entry,
                                      struct file *file, char __user *buf,
                                      size_t count, loff_t pos)
 {
-        long size;
         struct gus_proc_private *priv = entry->private_data;
         struct snd_gus_card *gus = priv->gus;
         int err;
 
-        size = count;
-        if (pos + size > priv->size)
-                size = (long)priv->size - pos;
-        if (size > 0) {
-                if ((err = snd_gus_dram_read(gus, buf, pos, size, priv->rom)) < 0)
-                        return err;
-                return size;
-        }
-        return 0;
+        err = snd_gus_dram_read(gus, buf, pos, count, priv->rom);
+        if (err < 0)
+                return err;
+        return count;
 }                       
 
 static loff_t snd_gf1_mem_proc_llseek(struct snd_info_entry *entry,
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;