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Commit b0775ca5 authored by Stephen Hines's avatar Stephen Hines
Browse files

Switch to memcpy for accessing misaligned data. 

Bug: http://b/31532493

Using misaligned pointers forces us to potentially take the address of
members in a packed structure (which is now a warning/error in the
latest Clang). Using memcpy() is the proper way to handle this kind of
problem, as the compiler can insert the proper instructions (and usually
elide the memcpy() entirely).

Test: Built correctly with updated compilers.
Change-Id: Ia1f6eb62cf19404ff76b71d3c6c7ffffa1403120
parent a7947755

base/include/android-base/memory.h

+7 −13
Original line number Diff line number Diff line
@@ -20,25 +20,19 @@ 
namespace android {

namespace base {



// Use packed structures for access to unaligned data on targets with alignment

// Use memcpy for access to unaligned data on targets with alignment

// restrictions.  The compiler will generate appropriate code to access these

// structures without generating alignment exceptions.

template <typename T>

static inline T get_unaligned(const T* address) {

  struct unaligned {

    T v;

  } __attribute__((packed));

  const unaligned* p = reinterpret_cast<const unaligned*>(address);

  return p->v;

static inline T get_unaligned(const void* address) {

  T result;

  memcpy(&result, address, sizeof(T));

  return result;

}



template <typename T>

static inline void put_unaligned(T* address, T v) {

  struct unaligned {

    T v;

  } __attribute__((packed));

  unaligned* p = reinterpret_cast<unaligned*>(address);

  p->v = v;

static inline void put_unaligned(void* address, T v) {

  memcpy(address, &v, sizeof(T));

}



} // namespace base

gatekeeperd/SoftGateKeeper.h

+1 −1
Original line number Diff line number Diff line
@@ -152,7 +152,7 @@ public: 
    }



    bool DoVerify(const password_handle_t *expected_handle, const SizedBuffer &password) {

        uint64_t user_id = android::base::get_unaligned(&expected_handle->user_id);

        uint64_t user_id = android::base::get_unaligned<secure_id_t>(&expected_handle->user_id);

        FastHashMap::const_iterator it = fast_hash_map_.find(user_id);

        if (it != fast_hash_map_.end() && VerifyFast(it->second, password)) {

            return true;