Re: [PATCH] ipc: explicitly clear stack memory in user structs

[Pekka Enberg]

On Tue, Oct 26, 2010 at 2:58 AM, Kees Cook <kees.cook@xxxxxxxxxxxxx> wrote:
> CVE-2010-4072
>
> The old shm interface will leak a few bytes of stack contents. Explicitly
> clear structure using memset instead of C99-style initialization in case
> there are ever holes in the packing.
>
> Cc: stable <stable@xxxxxxxxxx>
> Signed-off-by: Kees Cook <kees.cook@xxxxxxxxxxxxx>

This looks like a genuine bug fix but I don't see this patch in
mainline. Why is that?

> ---
>
> This was originally sent as http://lkml.org/lkml/2010/10/6/486 but was
> never taken into any tree.
>
> ---
>  ipc/shm.c |    2 ++
>  1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/ipc/shm.c b/ipc/shm.c
> index 52ed77e..f943b1e 100644
> --- a/ipc/shm.c
> +++ b/ipc/shm.c
> @@ -473,6 +473,7 @@ static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_
>            {
>                struct shmid_ds out;
>
> +               memset(&out, 0, sizeof(out));
>                ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
>                out.shm_segsz   = in->shm_segsz;
>                out.shm_atime   = in->shm_atime;
> @@ -524,6 +525,7 @@ static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminf
>            {
>                struct shminfo out;
>
> +               memset(&out, 0, sizeof(out));
>                if(in->shmmax > INT_MAX)
>                        out.shmmax = INT_MAX;
>                else
> --
> 1.7.1
>
> --
> Kees Cook
> Ubuntu Security Team
> --
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