diff options
Diffstat (limited to 'include/media/stagefright/foundation/ABase.h')
-rw-r--r-- | include/media/stagefright/foundation/ABase.h | 29 |
1 files changed, 29 insertions, 0 deletions
diff --git a/include/media/stagefright/foundation/ABase.h b/include/media/stagefright/foundation/ABase.h index 9eceea3..72e3d87 100644 --- a/include/media/stagefright/foundation/ABase.h +++ b/include/media/stagefright/foundation/ABase.h @@ -18,8 +18,37 @@ #define A_BASE_H_ +#define ARRAY_SIZE(a) (sizeof(a) / sizeof(*(a))) + #define DISALLOW_EVIL_CONSTRUCTORS(name) \ name(const name &); \ name &operator=(const name &) +/* Returns true if the size parameter is safe for new array allocation (32-bit) + * + * Example usage: + * + * if (!isSafeArraySize<uint32_t>(arraySize)) { + * return BAD_VALUE; + * } + * ... + * uint32_t *myArray = new uint32_t[arraySize]; + * + * There is a bug in gcc versions earlier than 4.8 where the new[] array allocation + * will overflow in the internal 32 bit heap allocation, resulting in an + * underallocated array. This is a security issue that allows potential overwriting + * of other heap data. + * + * An alternative to checking is to create a safe new array template function which + * either throws a std::bad_alloc exception or returns NULL/nullptr_t; NULL considered + * safe since normal access of NULL throws an exception. + * + * https://securityblog.redhat.com/2012/10/31/array-allocation-in-cxx/ + */ +template <typename T, typename S> +bool isSafeArraySize(S size) { + return size >= 0 // in case S is signed, ignored if not. + && size <= 0xffffffff / sizeof(T); // max-unsigned-32-bit-int / element-size. +} + #endif // A_BASE_H_ |