bpo-28055: Fix unaligned accesses in siphash24(). (GH-6123)
The hash implementation casts the input pointer to uint64_t* and directly reads
from this, which may cause unaligned accesses. Use memcpy() instead so this code
will not crash with SIGBUS on sparc.
https://bugs.gentoo.org/show_bug.cgi?id=636400
(cherry picked from commit 1e2ec8a996
)
Co-authored-by: Rolf Eike Beer <eike@sf-mail.de>
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Fix unaligned accesses in siphash24(). Patch by Rolf Eike Beer.
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@ -366,7 +366,7 @@ static PyHash_FuncDef PyHash_Func = {fnv, "fnv", 8 * SIZEOF_PY_HASH_T,
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static uint64_t
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siphash24(uint64_t k0, uint64_t k1, const void *src, Py_ssize_t src_sz) {
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uint64_t b = (uint64_t)src_sz << 56;
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const uint64_t *in = (uint64_t*)src;
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const uint8_t *in = (uint8_t*)src;
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uint64_t v0 = k0 ^ 0x736f6d6570736575ULL;
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uint64_t v1 = k1 ^ 0x646f72616e646f6dULL;
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@ -375,12 +375,13 @@ siphash24(uint64_t k0, uint64_t k1, const void *src, Py_ssize_t src_sz) {
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uint64_t t;
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uint8_t *pt;
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uint8_t *m;
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while (src_sz >= 8) {
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uint64_t mi = _le64toh(*in);
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in += 1;
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src_sz -= 8;
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uint64_t mi;
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memcpy(&mi, in, sizeof(mi));
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mi = _le64toh(mi);
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in += sizeof(mi);
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src_sz -= sizeof(mi);
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v3 ^= mi;
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DOUBLE_ROUND(v0,v1,v2,v3);
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v0 ^= mi;
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@ -388,15 +389,14 @@ siphash24(uint64_t k0, uint64_t k1, const void *src, Py_ssize_t src_sz) {
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t = 0;
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pt = (uint8_t *)&t;
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m = (uint8_t *)in;
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switch (src_sz) {
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case 7: pt[6] = m[6]; /* fall through */
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case 6: pt[5] = m[5]; /* fall through */
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case 5: pt[4] = m[4]; /* fall through */
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case 4: memcpy(pt, m, sizeof(uint32_t)); break;
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case 3: pt[2] = m[2]; /* fall through */
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case 2: pt[1] = m[1]; /* fall through */
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case 1: pt[0] = m[0]; /* fall through */
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case 7: pt[6] = in[6]; /* fall through */
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case 6: pt[5] = in[5]; /* fall through */
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case 5: pt[4] = in[4]; /* fall through */
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case 4: memcpy(pt, in, sizeof(uint32_t)); break;
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case 3: pt[2] = in[2]; /* fall through */
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case 2: pt[1] = in[1]; /* fall through */
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case 1: pt[0] = in[0]; /* fall through */
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}
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b |= _le64toh(t);
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