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>

1 files changed, 16 insertions, 30 deletions

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,