[PATCH][BUG] fix memory leak on reading cpuset files after seekingbeyond eof

From: KUROSAWA Takahiro
Date: Wed Sep 28 2005 - 04:26:23 EST


On Tue, 27 Sep 2005 20:39:02 +0900
KUROSAWA Takahiro <kurosawa@xxxxxxxxxxxxx> wrote:

> On Tue, 27 Sep 2005 01:37:51 -0700
> Paul Jackson <pj@xxxxxxx> wrote:
>
> > The above reminds me of a bug fix that you provided in the previous
> > patch set, for the case *ppos >= eof. I wonder if we have duplicated
> > code here.
> Ah, yes, we need to fix the bug in the cpuset code introduced by me...

I fixed the bug. Sorry for my previous incomplete patch.
The following patch is against linux-2.6.14-rc2.

Signed-off-by: KUROSAWA Takahiro <kurosawa@xxxxxxxxxxxxx>

--- from-0001/kernel/cpuset.c
+++ to-work/kernel/cpuset.c 2005-09-28 17:42:00.759401736 +0900
@@ -969,7 +969,7 @@ static ssize_t cpuset_common_file_read(s
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(s
*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:
-
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