On Sun, Mar 08, 2020 at 04:35:26PM -0500, Eric W. Biederman wrote:
>
> Make it clear that current only needs to be computed once in
> flush_old_exec. This may have some efficiency improvements and it
> makes the code easier to change.
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
modulo my suggestion of adding more comments (it could even be kerndoc!)
that explicitly states that "me" should always be "current", yup, looks
good:
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
-Kees
> ---
> fs/exec.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/fs/exec.c b/fs/exec.c
> index db17be51b112..c3f34791f2f0 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -1260,13 +1260,14 @@ void __set_task_comm(struct task_struct *tsk, const char *buf, bool exec)
> */
> int flush_old_exec(struct linux_binprm * bprm)
> {
> + struct task_struct *me = current;
> int retval;
>
> /*
> * Make sure we have a private signal table and that
> * we are unassociated from the previous thread group.
> */
> - retval = de_thread(current);
> + retval = de_thread(me);
> if (retval)
> goto out;
>
> @@ -1294,10 +1295,10 @@ int flush_old_exec(struct linux_binprm * bprm)
> bprm->mm = NULL;
>
> set_fs(USER_DS);
> - current->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
> + me->flags &= ~(PF_RANDOMIZE | PF_FORKNOEXEC | PF_KTHREAD |
> PF_NOFREEZE | PF_NO_SETAFFINITY);
> flush_thread();
> - current->personality &= ~bprm->per_clear;
> + me->personality &= ~bprm->per_clear;
>
> /*
> * We have to apply CLOEXEC before we change whether the process is
> @@ -1305,7 +1306,7 @@ int flush_old_exec(struct linux_binprm * bprm)
> * trying to access the should-be-closed file descriptors of a process
> * undergoing exec(2).
> */
> - do_close_on_exec(current->files);
> + do_close_on_exec(me->files);
> return 0;
>
> out:
> --
> 2.25.0
>
--
Kees Cook
