1 files changed, 6 insertions, 2 deletions

diff --git a/fs/libfs.c b/fs/libfs.c
index dcec3d3ea64f..662a28e4f667 100644
--- a/fs/libfs.c
+++ b/fs/libfs.c
@@ -527,14 +527,18 @@ ssize_t simple_read_from_buffer(void __user *to, size_t count, loff_t *ppos,
                                 const void *from, size_t available)
 {
         loff_t pos = *ppos;
+        size_t ret;
+
         if (pos < 0)
                 return -EINVAL;
-        if (pos >= available)
+        if (pos >= available || !count)
                 return 0;
         if (count > available - pos)
                 count = available - pos;
-        if (copy_to_user(to, from + pos, count))
+        ret = copy_to_user(to, from + pos, count);
+        if (ret == count)
                 return -EFAULT;
+        count -= ret;
         *ppos = pos + count;
         return count;
 }