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