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Commit 11d7bc52 authored by Jiyong Park's avatar Jiyong Park
Browse files

init: don't touch mmap_rnd_compat_bits on 64-bit only builds 

mmap_rnd_compat_bits is for address space randomization of 32-bit
applications on 64-bit system. Configuring it is not only unnecessary
for 64-bit "only" builds, but also can cause a boot failure if the
kernel is built without CONFIG_COMPAT which is the case for Microdroid.

Use ro.product.abilist32 to determine whether 32-bit applications are
supported and if not, don't configure it, but mmap_rnd_bits.

Bug: 237950549
Test: run Microdroid with the kernel built with aosp/2153639

Change-Id: Ifca6fa02f14ad4c7d8f9b2ab8852494c12945c3a
parent 46fa45d8

init/security.cpp

+3 −2
Original line number Original line Diff line number Diff line
@@ -15,6 +15,7 @@ 
 */

 */





#include "security.h"

#include "security.h"

#include "util.h"





#include <errno.h>

#include <errno.h>

#include <fcntl.h>

#include <fcntl.h>
@@ -106,12 +107,12 @@ Result<void> SetMmapRndBitsAction(const BuiltinArguments&) { 
    return {};

    return {};

#elif defined(__aarch64__)

#elif defined(__aarch64__)

    // arm64 supports 18 - 33 bits depending on pagesize and VA_SIZE

    // arm64 supports 18 - 33 bits depending on pagesize and VA_SIZE

    if (SetMmapRndBitsMin(33, 24, false) && SetMmapRndBitsMin(16, 16, true)) {

    if (SetMmapRndBitsMin(33, 24, false) && (!Has32BitAbi() || SetMmapRndBitsMin(16, 16, true))) {

        return {};

        return {};

    }

    }

#elif defined(__x86_64__)

#elif defined(__x86_64__)

    // x86_64 supports 28 - 32 bits

    // x86_64 supports 28 - 32 bits

    if (SetMmapRndBitsMin(32, 32, false) && SetMmapRndBitsMin(16, 16, true)) {

    if (SetMmapRndBitsMin(32, 32, false) && (!Has32BitAbi() || SetMmapRndBitsMin(16, 16, true))) {

        return {};

        return {};

    }

    }

#elif defined(__arm__) || defined(__i386__)

#elif defined(__arm__) || defined(__i386__)

init/util.cpp

+5 −0
Original line number Original line Diff line number Diff line
@@ -733,5 +733,10 @@ bool IsMicrodroid() { 
    return is_microdroid;

    return is_microdroid;

}

}





bool Has32BitAbi() {

    static bool has = !android::base::GetProperty("ro.product.cpu.abilist32", "").empty();

    return has;

}



}  // namespace init

}  // namespace init

}  // namespace android
 
}  // namespace android

init/util.h

+1 −0
Original line number Original line Diff line number Diff line
@@ -106,5 +106,6 @@ bool IsDefaultMountNamespaceReady(); 
void SetDefaultMountNamespaceReady();

void SetDefaultMountNamespaceReady();





bool IsMicrodroid();

bool IsMicrodroid();

bool Has32BitAbi();

}  // namespace init

}  // namespace init

}  // namespace android
 
}  // namespace android