From patchwork Tue Dec 12 19:28:38 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: Revert "exec: avoid RLIMIT_STACK races with prlimit()" From: Kees Cook X-Patchwork-Id: 10108209 Message-Id: <20171212192838.GA14592@beast> To: Linus Torvalds Cc: Laura Abbott , =?utf-8?B?VG9tw6HFoQ==?= Trnka , linux-kernel@vger.kernel.org Date: Tue, 12 Dec 2017 11:28:38 -0800 This reverts commit 04e35f4495dd560db30c25efca4eecae8ec8c375. SELinux runs with secureexec for all non-"noatsecure" domain transitions, which means lots of processes end up hitting the stack hard-limit change that was introduced in order to fix a race with prlimit(). That race fix will need to be redesigned. Reported-by: Laura Abbott Reported-by: Tomáš Trnka Cc: stable@vger.kernel.org Signed-off-by: Kees Cook --- fs/exec.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/fs/exec.c b/fs/exec.c index 6be2aa0ab26f..1d6243d9f2b6 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -1340,15 +1340,10 @@ void setup_new_exec(struct linux_binprm * bprm) * avoid bad behavior from the prior rlimits. This has to * happen before arch_pick_mmap_layout(), which examines * RLIMIT_STACK, but after the point of no return to avoid - * races from other threads changing the limits. This also - * must be protected from races with prlimit() calls. + * needing to clean up the change on failure. */ - task_lock(current->group_leader); if (current->signal->rlim[RLIMIT_STACK].rlim_cur > _STK_LIM) current->signal->rlim[RLIMIT_STACK].rlim_cur = _STK_LIM; - if (current->signal->rlim[RLIMIT_STACK].rlim_max > _STK_LIM) - current->signal->rlim[RLIMIT_STACK].rlim_max = _STK_LIM; - task_unlock(current->group_leader); } arch_pick_mmap_layout(current->mm);