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Tests: check declared buffer alignment at compile time

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Check wrapper type alignment in both test suites so incidental alignment
can't hide an empty CRYPTOPP_ALIGN_DATA, including in ASan builds.
Clarify that the compiler may fold the existing address checks.
This commit is contained in:
Mounir IDRASSI
2026-10-13 20:18:23 +09:00
parent 0ae91a9049
commit b4c4290588
2 changed files with 32 additions and 9 deletions
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src/Common/Tests.c
+16 -4
View File
@@ -1282,12 +1282,24 @@ BOOL TestSectorBufEncryption (PCRYPTO_INFO ci)
}
#ifndef TC_WINDOWS_DRIVER
// Must stay smaller than the alignment under test: the ABI aligns larger objects by itself.
#define TC_ALIGNMENT_PROBE_SIZE 4
/* Verifies that CRYPTOPP_ALIGN_DATA actually delivers the alignment it requests. It expands
to nothing for compilers that are neither MSVC nor GCC/Clang (see Crypto/config.h), and the
SIMD backends issue aligned loads against buffers declared with it. */
/* Check type alignment at compile time: static probes can be aligned even with an
empty CRYPTOPP_ALIGN_DATA, for example in AddressSanitizer builds. */
typedef struct
{
CRYPTOPP_ALIGN_DATA(TC_DERIVED_KEY_BUFFER_ALIGNMENT) unsigned char buffer[TC_ALIGNMENT_PROBE_SIZE];
} DerivedKeyAlignmentProbe;
typedef struct
{
CRYPTOPP_ALIGN_DATA(TC_KEY_INFO_BUFFER_ALIGNMENT) unsigned char buffer[TC_ALIGNMENT_PROBE_SIZE];
} KeyInfoAlignmentProbe;
typedef char DerivedKeyAlignmentCheck[(__alignof (DerivedKeyAlignmentProbe) >= TC_DERIVED_KEY_BUFFER_ALIGNMENT) ? 1 : -1];
typedef char KeyInfoAlignmentCheck[(__alignof (KeyInfoAlignmentProbe) >= TC_KEY_INFO_BUFFER_ALIGNMENT) ? 1 : -1];
/* The compiler may fold the address checks using the declared alignment. */
static BOOL TestBufferAlignment (void)
{
static CRYPTOPP_ALIGN_DATA(TC_DERIVED_KEY_BUFFER_ALIGNMENT) unsigned char derivedKeyProbe[TC_ALIGNMENT_PROBE_SIZE];
src/Volume/EncryptionTest.cpp
+16 -5
View File
@@ -75,15 +75,26 @@ namespace VeraCrypt
TestAll (true);
}
// Must stay smaller than the alignment under test: the ABI aligns larger objects by itself.
#define TC_ALIGNMENT_PROBE_SIZE 4
// Verifies that CRYPTOPP_ALIGN_DATA actually delivers the alignment it requests.
// It expands to nothing for compilers that are neither MSVC nor GCC/Clang (see
// Crypto/config.h), and the SIMD backends issue aligned loads against buffers
// declared with it, so a silent expansion to nothing would fault at run time.
// The compiler may fold the address checks using the declared alignment.
void EncryptionTest::TestAlignment ()
{
// Check type alignment at compile time: static probes can be aligned even with an
// empty CRYPTOPP_ALIGN_DATA, for example in AddressSanitizer builds.
struct DerivedKeyAlignmentProbe
{
CRYPTOPP_ALIGN_DATA(TC_DERIVED_KEY_BUFFER_ALIGNMENT) uint8 buffer[TC_ALIGNMENT_PROBE_SIZE];
};
struct KeyInfoAlignmentProbe
{
CRYPTOPP_ALIGN_DATA(TC_KEY_INFO_BUFFER_ALIGNMENT) uint8 buffer[TC_ALIGNMENT_PROBE_SIZE];
};
static_assert (alignof (DerivedKeyAlignmentProbe) >= TC_DERIVED_KEY_BUFFER_ALIGNMENT, "Insufficient derived key buffer alignment");
static_assert (alignof (KeyInfoAlignmentProbe) >= TC_KEY_INFO_BUFFER_ALIGNMENT, "Insufficient key info buffer alignment");
static CRYPTOPP_ALIGN_DATA(TC_DERIVED_KEY_BUFFER_ALIGNMENT) uint8 derivedKeyProbe[TC_ALIGNMENT_PROBE_SIZE];
static CRYPTOPP_ALIGN_DATA(TC_KEY_INFO_BUFFER_ALIGNMENT) uint8 keyInfoProbe[TC_ALIGNMENT_PROBE_SIZE];