Fix crash with --use-gl=egl on Linux.

content/common/sandbox_linux/bpf_gpu_policy_linux.cc

 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/common/sandbox_linux/bpf_gpu_policy_linux.h"
 
 #include <dlfcn.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/socket.h>
@@ skipping 151 matching lines @@
 bool UpdateProcessTypeAndEnableSandbox(sandbox::bpf_dsl::SandboxBPFDSLPolicy* (
     *broker_sandboxer_allocator)(void)) {
   DCHECK(broker_sandboxer_allocator);
   UpdateProcessTypeToGpuBroker();
   return SandboxSeccompBPF::StartSandboxWithExternalPolicy(
       make_scoped_ptr(broker_sandboxer_allocator()));
 }
 
 }  // namespace
 
-GpuProcessPolicy::GpuProcessPolicy() : broker_process_(NULL) {}
+GpuProcessPolicy::GpuProcessPolicy() : GpuProcessPolicy(false) {
+}
+
+GpuProcessPolicy::GpuProcessPolicy(bool allow_mincore)
+    : broker_process_(NULL), allow_mincore_(allow_mincore) {
+}
 
 GpuProcessPolicy::~GpuProcessPolicy() {}
 
 // Main policy for x86_64/i386. Extended by CrosArmGpuProcessPolicy.
 ResultExpr GpuProcessPolicy::EvaluateSyscall(int sysno) const {
   switch (sysno) {
     case __NR_ioctl:
 #if defined(__i386__) || defined(__x86_64__) || defined(__mips__)
     // The Nvidia driver uses flags not in the baseline policy
     // (MAP_LOCKED | MAP_EXECUTABLE | MAP_32BIT)
     case __NR_mmap:
 #endif
     // We also hit this on the linux_chromeos bot but don't yet know what
     // weird flags were involved.
     case __NR_mprotect:
     // TODO(jln): restrict prctl.
     case __NR_prctl:
       return Allow();
     case __NR_access:
     case __NR_open:
     case __NR_openat:
       DCHECK(broker_process_);
       return Trap(GpuSIGSYS_Handler, broker_process_);
     case __NR_setpriority:
       return sandbox::RestrictGetSetpriority(GetPolicyPid());
     case __NR_sched_getaffinity:
     case __NR_sched_setaffinity:
       return sandbox::RestrictSchedTarget(GetPolicyPid(), sysno);
+    case __NR_mincore:
+      if (allow_mincore_)
+        return Allow();

[Jorge Lucangeli Obes, 2014/10/20 19:01:07]

We try to keep this in alphabetical order, but it's tricky since if we put it
above mmap() it will fall through.

I think the best solution is to do:

case __NR_ioctl:
  return Allow();
case __NR_mincore:
  if (allow_mincore_)
    return Allow();
  else
    return SandboxBPFBasePolicy::EvaluateSyscall(sysno);

And put __NR_mincore right above mmap.

     default:
       if (SyscallSets::IsEventFd(sysno))
         return Allow();
 
       // Default on the baseline policy.
       return SandboxBPFBasePolicy::EvaluateSyscall(sysno);
   }
 }
 
 bool GpuProcessPolicy::PreSandboxHook() {
@@ skipping 59 matching lines @@
   broker_process_ = new BrokerProcess(GetFSDeniedErrno(),
                                       read_whitelist,
                                       write_whitelist);
   // The initialization callback will perform generic initialization and then
   // call broker_sandboxer_callback.
   CHECK(broker_process_->Init(base::Bind(&UpdateProcessTypeAndEnableSandbox,
                                          broker_sandboxer_allocator)));
 }
 
 }  // namespace content