From a6a7d9a4ad84da293071fbbbc7eedd2ce51abdf4 Mon Sep 17 00:00:00 2001 From: "riku.voipio" Date: Wed, 27 Jan 2016 09:13:57 -0800 Subject: [PATCH 2/3] sandbox arm64: align stack 16 bytes chrome fails to start with user namespace sandboxing: [866:866:0120/134742:FATAL:zygote_host_impl_linux.cc(182)] Check failed: process.IsValid(). Failed to launch zygote process With strace.. clone(child_stack=0x7ffd28fd98, flags=CLONE_NEWUSER|CLONE_NEWPID|CLONE_NEWNET|SIGCHLD) = -1 EINVAL (Invalid argument) Which compared to kernel sources[1], shows that stack needs to be 16 bytes aligned. because stack grows downward, this patch assumes PTHREAD_STACK_MIN is dividable by 16 too. [1] http://lxr.free-electrons.com/source/arch/arm64/kernel/process.c#L267 BUG=581018 R=keescook@chromium.org,jln@chromium.org,rsesek@chromium.org,thakis@chromium.org TEST=base_unittests ProcessUtilTest.* and sandbox_linux_unittests NamespaceSandboxTest.* Review URL: https://codereview.chromium.org/1617763002 Cr-Commit-Position: refs/heads/master@{#371809} --- base/process/launch_posix.cc | 2 +- sandbox/linux/services/credentials.cc | 3 ++- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/base/process/launch_posix.cc b/base/process/launch_posix.cc index 4bd3da3..4019de5 100644 --- a/base/process/launch_posix.cc +++ b/base/process/launch_posix.cc @@ -736,7 +736,7 @@ NOINLINE pid_t CloneAndLongjmpInChild(unsigned long flags, // internal pid cache. The libc interface unfortunately requires // specifying a new stack, so we use setjmp/longjmp to emulate // fork-like behavior. - char stack_buf[PTHREAD_STACK_MIN]; + char stack_buf[PTHREAD_STACK_MIN] ALIGNAS(16); #if defined(ARCH_CPU_X86_FAMILY) || defined(ARCH_CPU_ARM_FAMILY) || \ defined(ARCH_CPU_MIPS64_FAMILY) || defined(ARCH_CPU_MIPS_FAMILY) // The stack grows downward. diff --git a/sandbox/linux/services/credentials.cc b/sandbox/linux/services/credentials.cc index fb6b6b4..76038af 100644 --- a/sandbox/linux/services/credentials.cc +++ b/sandbox/linux/services/credentials.cc @@ -16,6 +16,7 @@ #include #include "base/bind.h" +#include "base/compiler_specific.h" #include "base/files/file_path.h" #include "base/files/file_util.h" #include "base/logging.h" @@ -94,7 +95,7 @@ bool ChrootToSafeEmptyDir() { // /proc/tid directory for the thread (since /proc may not be aware of the // PID namespace). With a process, we can just use /proc/self. pid_t pid = -1; - char stack_buf[PTHREAD_STACK_MIN]; + char stack_buf[PTHREAD_STACK_MIN] ALIGNAS(16); #if defined(ARCH_CPU_X86_FAMILY) || defined(ARCH_CPU_ARM_FAMILY) || \ defined(ARCH_CPU_MIPS64_FAMILY) || defined(ARCH_CPU_MIPS_FAMILY) // The stack grows downward. -- 2.7.2