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luci-base: further hash calculation signedness bugfixes

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- cbi.js: make sure to treat single bytes as signed char when
   handling end cases

 - template_lmo.c: make sure to treat single bytes as signed
   char when handling end cases, avoids hash miscalculations
   on ARM

Signed-off-by: Jo-Philipp Wich <jo@mein.io>
This commit is contained in:
Jo-Philipp Wich 2018-11-19 13:28:52 +01:00
parent c55436e36f
commit 51de74d520
2 changed files with 17 additions and 8 deletions
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21
modules/luci-base/htdocs/luci-static/resources/cbi.js
View file

@ -15,6 +15,15 @@ var cbi_d = [];
var cbi_t = [];
var cbi_strings = { path: {}, label: {} };
function s8(bytes, off) {
var n = bytes[off];
return (n > 0x7F) ? (n - 256) >>> 0 : n;
}
function u16(bytes, off) {
return ((bytes[off + 1] << 8) + bytes[off]) >>> 0;
}
function sfh(s) {
if (s === null || s.length === 0)
return null;
@ -48,8 +57,8 @@ function sfh(s) {
off = 0, tmp;
while (len--) {
hash += ((bytes[off + 1] << 8) + bytes[off]) >>> 0;
tmp = ((((bytes[off + 3] << 8) + bytes[off + 2]) << 11) ^ hash) >>> 0;
hash += u16(bytes, off);
tmp = ((u16(bytes, off + 2) << 11) ^ hash) >>> 0;
hash = ((hash << 16) ^ tmp) >>> 0;
hash += hash >>> 11;
off += 4;
@ -57,20 +66,20 @@ function sfh(s) {
switch ((bytes.length & 3) >>> 0) {
case 3:
hash += ((bytes[off + 1] << 8) + bytes[off]) >>> 0;
hash += u16(bytes, off);
hash = (hash ^ (hash << 16)) >>> 0;
hash = (hash ^ (bytes[off + 2] << 18)) >>> 0;
hash = (hash ^ (s8(bytes, off + 2) << 18)) >>> 0;
hash += hash >>> 11;
break;
case 2:
hash += ((bytes[off + 1] << 8) + bytes[off]) >>> 0;
hash += u16(bytes, off);
hash = (hash ^ (hash << 11)) >>> 0;
hash += hash >>> 17;
break;
case 1:
hash += bytes[off];
hash += s8(bytes, off);
hash = (hash ^ (hash << 10)) >>> 0;
hash += hash >>> 1;
break;

4
modules/luci-base/src/template_lmo.c
View file

@ -46,14 +46,14 @@ uint32_t sfh_hash(const char *data, int len)
switch (rem) {
case 3: hash += sfh_get16(data);
hash ^= hash << 16;
hash ^= data[sizeof(uint16_t)] << 18;
hash ^= (signed char)data[sizeof(uint16_t)] << 18;
hash += hash >> 11;
break;
case 2: hash += sfh_get16(data);
hash ^= hash << 11;
hash += hash >> 17;
break;
case 1: hash += *data;
case 1: hash += (signed char)*data;
hash ^= hash << 10;
hash += hash >> 1;
}