Fix an occasional CI failure due to unaligned access

This happens rarely, but only because very few CI runs
use the exotic CPU type that is necessary to execute
anything within rsaz_exp_x2.c and enable UBSAN at the same time.

crypto/bn/rsaz_exp_x2.c:562:20: runtime error: load of misaligned address 0x612000022cc6 for type 'uint64_t' (aka 'unsigned long'), which requires 8 byte alignment
0x612000022cc6: note: pointer points here
 84 a3 78 e0 8e 8d  4a a5 51 9c 57 d0 d6 41  f3 26 d1 4e e1 98 42 b5  3a 9f 04 f1 73 d2 1d bf  73 44
             ^
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior crypto/bn/rsaz_exp_x2.c:562:20 in
../../util/wrap.pl ../../fuzz/server-test ../../fuzz/corpora/server => 1
not ok 2 - Fuzzing server

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19394)

diff --git a/crypto/bn/rsaz_exp_x2.c b/crypto/bn/rsaz_exp_x2.c
index f979cebd6fb783474f6c66598fda23d36cfc73f7..e6d6e43f93b93cd2a75d0675d823b670437db4e4 100644 (file)
--- a/crypto/bn/rsaz_exp_x2.c
+++ b/crypto/bn/rsaz_exp_x2.c
@@ -25,11 +25,11 @@ NON_EMPTY_TRANSLATION_UNIT
 # include <string.h>
 
 # if defined(__GNUC__)
-#  define ALIGN64 __attribute__((aligned(64)))
+#  define ALIGN1  __attribute__((aligned(1)))
 # elif defined(_MSC_VER)
-#  define ALIGN64 __declspec(align(64))
+#  define ALIGN1  __declspec(align(1))
 # else
-#  define ALIGN64
+#  define ALIGN1
 # endif
 
 # define ALIGN_OF(ptr, boundary) \
@@ -47,6 +47,8 @@ NON_EMPTY_TRANSLATION_UNIT
 # define NUMBER_OF_REGISTERS(digits_num, register_size)            \
     (((digits_num) * 64 + (register_size) - 1) / (register_size))
 
+typedef uint64_t ALIGN1 uint64_t_align1;
+
 static ossl_inline uint64_t get_digit(const uint8_t *in, int in_len);
 static ossl_inline void put_digit(uint8_t *out, int out_len, uint64_t digit);
 static void to_words52(BN_ULONG *out, int out_len, const BN_ULONG *in,
@@ -557,9 +559,9 @@ static void to_words52(BN_ULONG *out, int out_len,
     in_str = (uint8_t *)in;
 
     for (; in_bitsize >= (2 * DIGIT_SIZE); in_bitsize -= (2 * DIGIT_SIZE), out += 2) {
-        out[0] = (*(uint64_t *)in_str) & DIGIT_MASK;
+        out[0] = (*(uint64_t_align1 *)in_str) & DIGIT_MASK;
         in_str += 6;
-        out[1] = ((*(uint64_t *)in_str) >> 4) & DIGIT_MASK;
+        out[1] = ((*(uint64_t_align1 *)in_str) >> 4) & DIGIT_MASK;
         in_str += 7;
         out_len -= 2;
     }
@@ -618,9 +620,9 @@ static void from_words52(BN_ULONG *out, int out_bitsize, const BN_ULONG *in)
 
         for (; out_bitsize >= (2 * DIGIT_SIZE);
                out_bitsize -= (2 * DIGIT_SIZE), in += 2) {
-            (*(uint64_t *)out_str) = in[0];
+            (*(uint64_t_align1 *)out_str) = in[0];
             out_str += 6;
-            (*(uint64_t *)out_str) ^= in[1] << 4;
+            (*(uint64_t_align1 *)out_str) ^= in[1] << 4;
             out_str += 7;
         }