* [PATCH] ocfs2: drop a VLA in ocfs2_orphan_del()
@ 2018-03-13 19:51 Salvatore Mesoraca
2018-05-18 15:00 ` Kees Cook
0 siblings, 1 reply; 2+ messages in thread
From: Salvatore Mesoraca @ 2018-03-13 19:51 UTC (permalink / raw)
To: linux-kernel
Cc: kernel-hardening, Joel Becker, Kees Cook, Mark Fasheh,
Salvatore Mesoraca
Avoid a VLA[1] by using a real constant expression instead of a variable.
The compiler should be able to optimize the original code and avoid using
an actual VLA. Anyway this change is useful because it will avoid a false
positive with -Wvla, it might also help the compiler generating better
code.
[1] https://lkml.org/lkml/2018/3/7/621
Signed-off-by: Salvatore Mesoraca <s.mesoraca16@gmail.com>
---
fs/ocfs2/namei.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
index c801edd..41ef356 100644
--- a/fs/ocfs2/namei.c
+++ b/fs/ocfs2/namei.c
@@ -2332,8 +2332,7 @@ int ocfs2_orphan_del(struct ocfs2_super *osb,
struct buffer_head *orphan_dir_bh,
bool dio)
{
- const int namelen = OCFS2_DIO_ORPHAN_PREFIX_LEN + OCFS2_ORPHAN_NAMELEN;
- char name[namelen + 1];
+ char name[OCFS2_DIO_ORPHAN_PREFIX_LEN + OCFS2_ORPHAN_NAMELEN + 1];
struct ocfs2_dinode *orphan_fe;
int status = 0;
struct ocfs2_dir_lookup_result lookup = { NULL, };
--
1.9.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] ocfs2: drop a VLA in ocfs2_orphan_del()
2018-03-13 19:51 [PATCH] ocfs2: drop a VLA in ocfs2_orphan_del() Salvatore Mesoraca
@ 2018-05-18 15:00 ` Kees Cook
0 siblings, 0 replies; 2+ messages in thread
From: Kees Cook @ 2018-05-18 15:00 UTC (permalink / raw)
To: Andrew Morton
Cc: Salvatore Mesoraca, LKML, Kernel Hardening, Joel Becker, Mark Fasheh
On Tue, Mar 13, 2018 at 12:51 PM, Salvatore Mesoraca
<s.mesoraca16@gmail.com> wrote:
> Avoid a VLA[1] by using a real constant expression instead of a variable.
> The compiler should be able to optimize the original code and avoid using
> an actual VLA. Anyway this change is useful because it will avoid a false
> positive with -Wvla, it might also help the compiler generating better
> code.
>
> [1] https://lkml.org/lkml/2018/3/7/621
>
> Signed-off-by: Salvatore Mesoraca <s.mesoraca16@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Andrew, can you take this? It seems the most recent patch to ocfs2
went through your tree...
-Kees
> ---
> fs/ocfs2/namei.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/fs/ocfs2/namei.c b/fs/ocfs2/namei.c
> index c801edd..41ef356 100644
> --- a/fs/ocfs2/namei.c
> +++ b/fs/ocfs2/namei.c
> @@ -2332,8 +2332,7 @@ int ocfs2_orphan_del(struct ocfs2_super *osb,
> struct buffer_head *orphan_dir_bh,
> bool dio)
> {
> - const int namelen = OCFS2_DIO_ORPHAN_PREFIX_LEN + OCFS2_ORPHAN_NAMELEN;
> - char name[namelen + 1];
> + char name[OCFS2_DIO_ORPHAN_PREFIX_LEN + OCFS2_ORPHAN_NAMELEN + 1];
> struct ocfs2_dinode *orphan_fe;
> int status = 0;
> struct ocfs2_dir_lookup_result lookup = { NULL, };
> --
> 1.9.1
>
--
Kees Cook
Pixel Security
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2018-03-13 19:51 [PATCH] ocfs2: drop a VLA in ocfs2_orphan_del() Salvatore Mesoraca
2018-05-18 15:00 ` Kees Cook
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