* Re: mm: Don't touch uninitialized variable in do_pages_stat_array()
[not found] <200812161859.mBGIx1kR018513@hera.kernel.org>
@ 2008-12-16 19:47 ` Joe Perches
2008-12-16 20:35 ` Linus Torvalds
0 siblings, 1 reply; 2+ messages in thread
From: Joe Perches @ 2008-12-16 19:47 UTC (permalink / raw)
To: Linux Kernel Mailing List
Cc: KOSAKI Motohiro, Brice Goglin, Christoph Lameter,
KAMEZAWA Hiroyuki, Nick Piggin, Hugh Dickins, Linus Torvalds
On Tue, 2008-12-16 at 18:59 +0000, Linux Kernel Mailing List wrote:
> Gitweb: http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=c095adbc211f9f4e990eac7d6cb440de35e4f05f
> Commit: c095adbc211f9f4e990eac7d6cb440de35e4f05f
> Parent: a3dd15444baa9c7522c8457ab564c41219dfb44c
> Author: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> AuthorDate: Tue Dec 16 16:06:43 2008 +0900
> Committer: Linus Torvalds <torvalds@linux-foundation.org>
> CommitDate: Tue Dec 16 08:19:23 2008 -0800
>
> mm: Don't touch uninitialized variable in do_pages_stat_array()
>
> Commit 80bba1290ab5122c60cdb73332b26d288dc8aedd removed one necessary
> variable initialization. As a result following warning happened:
>
> CC mm/migrate.o
> mm/migrate.c: In function 'sys_move_pages':
> mm/migrate.c:1001: warning: 'err' may be used uninitialized in this function
>
> More unfortunately, if find_vma() failed, kernel read uninitialized
> memory.
>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> CC: Brice Goglin <Brice.Goglin@inria.fr>
> Cc: Christoph Lameter <clameter@sgi.com>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Nick Piggin <npiggin@suse.de>
> Cc: Hugh Dickins <hugh@veritas.com>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> ---
> mm/migrate.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index d8f0766..037b096 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -998,7 +998,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
> unsigned long addr = (unsigned long)(*pages);
> struct vm_area_struct *vma;
> struct page *page;
> - int err;
> + int err = -EFAULT;
>
> vma = find_vma(mm, addr);
> if (!vma)
> --
Perhaps this is more legible and avoids
the unnecessary assignments to err.
Signed-off-by: Joe Perches <joe@perches.com>
diff --git a/mm/migrate.c b/mm/migrate.c
index 037b096..ddfeeac 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -998,22 +998,25 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
unsigned long addr = (unsigned long)(*pages);
struct vm_area_struct *vma;
struct page *page;
- int err = -EFAULT;
+ int err;
vma = find_vma(mm, addr);
- if (!vma)
+ if (!vma) {
+ err = -EFAULT;
goto set_status;
+ }
page = follow_page(vma, addr, 0);
-
- err = PTR_ERR(page);
- if (IS_ERR(page))
+ if (IS_ERR(page)) {
+ err = PTR_ERR(page);
goto set_status;
+ }
- err = -ENOENT;
/* Use PageReserved to check for zero page */
- if (!page || PageReserved(page))
+ if (!page || PageReserved(page)) {
+ err = -ENOENT;
goto set_status;
+ }
err = page_to_nid(page);
set_status:
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