Revert "exec: avoid RLIMIT_STACK races with prlimit()"

kees · torvalds · commit 779f4e1c6c7c · 2017-12-17T14:26:25.000-08:00
This reverts commit 04e35f4. 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>
diff --git 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
-		 * 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);
