linux-kernel - Re: [PATCH] audit: return on memory error to avoid null pointer dereference

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Message-ID: <CAHC9VhQnVHgX99k2wTWyyxdaep-6k1WBnJ7t-AZmMNZJc_SN0A@mail.gmail.com>
Date:   Wed, 21 Feb 2018 18:49:16 -0500
From:   Paul Moore <paul@...l-moore.com>
To:     Richard Guy Briggs <rgb@...hat.com>
Cc:     Linux-Audit Mailing List <linux-audit@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Eric Paris <eparis@...hat.com>, Steve Grubb <sgrubb@...hat.com>
Subject: Re: [PATCH] audit: return on memory error to avoid null pointer dereference

On Wed, Feb 21, 2018 at 4:30 AM, Richard Guy Briggs <rgb@...hat.com> wrote:
> If there is a memory allocation error when trying to change an audit
> kernel feature value, the ignored allocation error will trigger a NULL
> pointer dereference oops on subsequent use of that pointer.  Return
> instead.
>
> Passes audit-testsuite.
> See: https://github.com/linux-audit/audit-kernel/issues/76
> Signed-off-by: Richard Guy Briggs <rgb@...hat.com>
> ---
>  kernel/audit.c | 2 ++
>  1 file changed, 2 insertions(+)

Thanks, merged.

In the future a "[PATCH v2]" prefix would be appreciated for patches
like this, it makes things a little easier in my inbox.

> diff --git a/kernel/audit.c b/kernel/audit.c
> index 5c25449..2de74be 100644
> --- a/kernel/audit.c
> +++ b/kernel/audit.c
> @@ -1059,6 +1059,8 @@ static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature
>                 return;
>
>         ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_FEATURE_CHANGE);
> +       if (!ab)
> +               return;
>         audit_log_task_info(ab, current);
>         audit_log_format(ab, " feature=%s old=%u new=%u old_lock=%u new_lock=%u res=%d",
>                          audit_feature_names[which], !!old_feature, !!new_feature,
> --
> 1.8.3.1

-- 
paul moore
www.paul-moore.com