Revert "exec: avoid RLIMIT_STACK races with prlimit()"
authorKees Cook <keescook@chromium.org>
Tue, 12 Dec 2017 19:28:38 +0000 (11:28 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Sun, 17 Dec 2017 22:26:25 +0000 (14:26 -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 <labbott@redhat.com>
Reported-by: Tomáš Trnka <trnka@scm.com>
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/exec.c

index 156f56acfe8e7cce22cac60a0cf35635d274a1c3..5688b5e1b9378107597a6117c8c3732889f951d2 100644 (file)
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1339,15 +1339,10 @@ 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
                 * 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_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);
        }
 
        arch_pick_mmap_layout(current->mm);