commit 732f522a42702494c4029da568a2603bb963e402
Author: Yawning Angel <yawn...@schwanenlied.me>
Date: Sun Mar 22 22:31:08 2015 +0000
Fix unaligned access in SipHash-2-4.
The compiler is allowed to assume that a "uint64_t *" is aligned
correctly, and will inline a version of memcpy that acts as such.
Use "uint8_t *", so the compiler does the right thing.
---
changes/bug15436 | 4 ++++
src/ext/csiphash.c | 16 +++++++++++++---
2 files changed, 17 insertions(+), 3 deletions(-)
diff --git a/changes/bug15436 b/changes/bug15436
new file mode 100644
index 0000000..4fa44d1
--- /dev/null
+++ b/changes/bug15436
@@ -0,0 +1,4 @@
+ o Minor bugfixes (portability):
+ - Use the correct datatype in the SipHash-2-4 function to prevent compilers
+ from assuming any sort of alignment. Fixes bug 15436; bugfix on
+ 0.2.5.3-alpha.
diff --git a/src/ext/csiphash.c b/src/ext/csiphash.c
index c247886..979990f 100644
--- a/src/ext/csiphash.c
+++ b/src/ext/csiphash.c
@@ -100,10 +100,18 @@ uint64_t siphash24(const void *src, unsigned long src_sz,
const struct sipkey *k
uint64_t k0 = key->k0;
uint64_t k1 = key->k1;
uint64_t b = (uint64_t)src_sz << 56;
+#ifdef UNALIGNED_OK
const uint64_t *in = (uint64_t*)src;
+#else
+ /* On platforms where alignment matters, if 'in' is a pointer to a
+ * datatype that must be aligned, the compiler is allowed to
+ * generate code that assumes that it is aligned as such.
+ */
+ const uint8_t *in = (uint8_t *)src;
+#endif
- uint64_t t;
- uint8_t *pt, *m;
+ uint64_t t;
+ uint8_t *pt, *m;
uint64_t v0 = k0 ^ 0x736f6d6570736575ULL;
uint64_t v1 = k1 ^ 0x646f72616e646f6dULL;
@@ -113,12 +121,14 @@ uint64_t siphash24(const void *src, unsigned long src_sz,
const struct sipkey *k
while (src_sz >= 8) {
#ifdef UNALIGNED_OK
uint64_t mi = _le64toh(*in);
+ in += 1;
#else
uint64_t mi;
memcpy(&mi, in, 8);
mi = _le64toh(mi);
+ in += 8;
#endif
- in += 1; src_sz -= 8;
+ src_sz -= 8;
v3 ^= mi;
DOUBLE_ROUND(v0,v1,v2,v3);
v0 ^= mi;
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