[PATCH] cpuset read past eof memory leak fix

Don't leak a page of memory if user reads a cpuset file past eof.

Signed-off-by: KUROSAWA Takahiro <kurosawa@valinux.co.jp>
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 79866bc..6a6e87b 100644 (file)
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -969,7 +969,7 @@ static ssize_t cpuset_common_file_read(struct file *file, char __user *buf,
        ssize_t retval = 0;
        char *s;
        char *start;
-       size_t n;
+       ssize_t n;
 
        if (!(page = (char *)__get_free_page(GFP_KERNEL)))
                return -ENOMEM;
@@ -999,12 +999,13 @@ static ssize_t cpuset_common_file_read(struct file *file, char __user *buf,
        *s++ = '\n';
        *s = '\0';
 
-       /* Do nothing if *ppos is at the eof or beyond the eof. */
-       if (s - page <= *ppos)
-               return 0;
-
        start = page + *ppos;
        n = s - start;
+
+       /* Do nothing if *ppos is at the eof or beyond the eof. */
+       if (n <= 0)
+               goto out;
+
        retval = n - copy_to_user(buf, start, min(n, nbytes));
        *ppos += retval;
 out: