From: ebiederm@xmission.com (Eric W. Biederman)
To: linux-security-module@vger.kernel.org
Subject: [PATCH v2 1/8] exec: Correct comments about "point of no return"
Date: Mon, 10 Jul 2017 03:46:18 -0500 [thread overview]
Message-ID: <87van0r86d.fsf@xmission.com> (raw)
In-Reply-To: <1499673451-66160-2-git-send-email-keescook@chromium.org> (Kees Cook's message of "Mon, 10 Jul 2017 00:57:24 -0700")
But you miss it.
The "point of no return" is the call to de_thread. Or aguably anything in
flush_old_exec. Once anything in the current task is modified you can't
return an error.
It very much does not have anything to do with brpm. It has
everything to do with current.
> diff --git a/fs/exec.c b/fs/exec.c
> index 904199086490..7842ae661e34 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -1285,7 +1285,14 @@ int flush_old_exec(struct linux_binprm * bprm)
> if (retval)
> goto out;
>
> - bprm->mm = NULL; /* We're using it now */
> + /*
> + * After clearing bprm->mm (to mark that current is using the
> + * prepared mm now), we are at the point of no return. If
> + * anything from here on returns an error, the check in
> + * search_binary_handler() will kill current (since the mm has
> + * been replaced).
> + */
> + bprm->mm = NULL;
>
> set_fs(USER_DS);
> current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
Eric
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next prev parent reply other threads:[~2017-07-10 8:46 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-10 7:57 [PATCH v2 0/8] exec: Use sane stack rlimit under secureexec Kees Cook
2017-07-10 7:57 ` [PATCH v2 1/8] exec: Correct comments about "point of no return" Kees Cook
2017-07-10 8:46 ` Eric W. Biederman [this message]
2017-07-10 16:04 ` Kees Cook
[not found] ` <87pod8mdad.fsf@xmission.com>
2017-07-18 6:39 ` Kees Cook
2017-07-18 13:12 ` Eric W. Biederman
2017-07-18 13:42 ` Kees Cook
2017-07-10 7:57 ` [PATCH v2 2/8] exec: Move security_bprm_secureexec() earlier Kees Cook
2017-07-10 8:57 ` Eric W. Biederman
2017-07-10 16:06 ` Kees Cook
[not found] ` <87bmosmcqv.fsf@xmission.com>
2017-07-11 2:07 ` Kees Cook
2017-07-18 6:45 ` Kees Cook
2017-07-10 7:57 ` [PATCH v2 3/8] exec: Use secureexec for setting dumpability Kees Cook
2017-07-10 7:57 ` [PATCH v2 4/8] exec: Use secureexec for clearing pdeath_signal Kees Cook
2017-07-10 7:57 ` [PATCH v2 5/8] smack: Remove redundant pdeath_signal clearing Kees Cook
2017-07-10 7:57 ` [PATCH v2 6/8] exec: Consolidate dumpability logic Kees Cook
2017-07-10 7:57 ` [PATCH v2 7/8] exec: Consolidate pdeath_signal clearing Kees Cook
2017-07-10 7:57 ` [PATCH v2 8/8] exec: Use sane stack rlimit under secureexec Kees Cook
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