Commit 057bf1afc9

LemonBoy <thatlemon@gmail.com>
2021-02-18 20:28:59
std: Add more error checking in hexToBytes
Prevent the function from turning into an endless loop that may or may not perform OOB accesses.
1 parent 4272f07
lib/std/crypto/25519/ed25519.zig
@@ -207,7 +207,7 @@ pub const Ed25519 = struct {
 
 test "ed25519 key pair creation" {
     var seed: [32]u8 = undefined;
-    try fmt.hexToBytes(seed[0..], "8052030376d47112be7f73ed7a019293dd12ad910b654455798b4667d73de166");
+    _ = try fmt.hexToBytes(seed[0..], "8052030376d47112be7f73ed7a019293dd12ad910b654455798b4667d73de166");
     const key_pair = try Ed25519.KeyPair.create(seed);
     var buf: [256]u8 = undefined;
     std.testing.expectEqualStrings(try std.fmt.bufPrint(&buf, "{X}", .{key_pair.secret_key}), "8052030376D47112BE7F73ED7A019293DD12AD910B654455798B4667D73DE1662D6F7455D97B4A3A10D7293909D1A4F2058CB9A370E43FA8154BB280DB839083");
@@ -216,7 +216,7 @@ test "ed25519 key pair creation" {
 
 test "ed25519 signature" {
     var seed: [32]u8 = undefined;
-    try fmt.hexToBytes(seed[0..], "8052030376d47112be7f73ed7a019293dd12ad910b654455798b4667d73de166");
+    _ = try fmt.hexToBytes(seed[0..], "8052030376d47112be7f73ed7a019293dd12ad910b654455798b4667d73de166");
     const key_pair = try Ed25519.KeyPair.create(seed);
 
     const sig = try Ed25519.sign("test", key_pair, null);
@@ -339,11 +339,11 @@ test "ed25519 test vectors" {
     };
     for (entries) |entry, i| {
         var msg: [entry.msg_hex.len / 2]u8 = undefined;
-        try fmt.hexToBytes(&msg, entry.msg_hex);
+        _ = try fmt.hexToBytes(&msg, entry.msg_hex);
         var public_key: [32]u8 = undefined;
-        try fmt.hexToBytes(&public_key, entry.public_key_hex);
+        _ = try fmt.hexToBytes(&public_key, entry.public_key_hex);
         var sig: [64]u8 = undefined;
-        try fmt.hexToBytes(&sig, entry.sig_hex);
+        _ = try fmt.hexToBytes(&sig, entry.sig_hex);
         if (entry.expected) |error_type| {
             std.testing.expectError(error_type, Ed25519.verify(sig, &msg, public_key));
         } else {
lib/std/crypto/25519/ristretto255.zig
@@ -173,7 +173,7 @@ test "ristretto255" {
     std.testing.expectEqualStrings(try std.fmt.bufPrint(&buf, "{X}", .{p.toBytes()}), "E2F2AE0A6ABC4E71A884A961C500515F58E30B6AA582DD8DB6A65945E08D2D76");
 
     var r: [Ristretto255.encoded_length]u8 = undefined;
-    try fmt.hexToBytes(r[0..], "6a493210f7499cd17fecb510ae0cea23a110e8d5b901f8acadd3095c73a3b919");
+    _ = try fmt.hexToBytes(r[0..], "6a493210f7499cd17fecb510ae0cea23a110e8d5b901f8acadd3095c73a3b919");
     var q = try Ristretto255.fromBytes(r);
     q = q.dbl().add(p);
     std.testing.expectEqualStrings(try std.fmt.bufPrint(&buf, "{X}", .{q.toBytes()}), "E882B131016B52C1D3337080187CF768423EFCCBB517BB495AB812C4160FF44E");
lib/std/crypto/25519/x25519.zig
@@ -85,8 +85,8 @@ const htest = @import("../test.zig");
 test "x25519 public key calculation from secret key" {
     var sk: [32]u8 = undefined;
     var pk_expected: [32]u8 = undefined;
-    try fmt.hexToBytes(sk[0..], "8052030376d47112be7f73ed7a019293dd12ad910b654455798b4667d73de166");
-    try fmt.hexToBytes(pk_expected[0..], "f1814f0e8ff1043d8a44d25babff3cedcae6c22c3edaa48f857ae70de2baae50");
+    _ = try fmt.hexToBytes(sk[0..], "8052030376d47112be7f73ed7a019293dd12ad910b654455798b4667d73de166");
+    _ = try fmt.hexToBytes(pk_expected[0..], "f1814f0e8ff1043d8a44d25babff3cedcae6c22c3edaa48f857ae70de2baae50");
     const pk_calculated = try X25519.recoverPublicKey(sk);
     std.testing.expectEqual(pk_calculated, pk_expected);
 }
lib/std/crypto/aes.zig
@@ -122,11 +122,11 @@ test "expand 128-bit key" {
     var exp: [16]u8 = undefined;
 
     for (enc.key_schedule.round_keys) |round_key, i| {
-        try std.fmt.hexToBytes(&exp, exp_enc[i]);
+        _ = try std.fmt.hexToBytes(&exp, exp_enc[i]);
         testing.expectEqualSlices(u8, &exp, &round_key.toBytes());
     }
     for (enc.key_schedule.round_keys) |round_key, i| {
-        try std.fmt.hexToBytes(&exp, exp_dec[i]);
+        _ = try std.fmt.hexToBytes(&exp, exp_dec[i]);
         testing.expectEqualSlices(u8, &exp, &round_key.toBytes());
     }
 }
@@ -144,11 +144,11 @@ test "expand 256-bit key" {
     var exp: [16]u8 = undefined;
 
     for (enc.key_schedule.round_keys) |round_key, i| {
-        try std.fmt.hexToBytes(&exp, exp_enc[i]);
+        _ = try std.fmt.hexToBytes(&exp, exp_enc[i]);
         testing.expectEqualSlices(u8, &exp, &round_key.toBytes());
     }
     for (dec.key_schedule.round_keys) |round_key, i| {
-        try std.fmt.hexToBytes(&exp, exp_dec[i]);
+        _ = try std.fmt.hexToBytes(&exp, exp_dec[i]);
         testing.expectEqualSlices(u8, &exp, &round_key.toBytes());
     }
 }
lib/std/crypto/blake3.zig
@@ -663,7 +663,7 @@ fn testBlake3(hasher: *Blake3, input_len: usize, expected_hex: [262]u8) void {
 
     // Compare to expected value
     var expected_bytes: [expected_hex.len / 2]u8 = undefined;
-    fmt.hexToBytes(expected_bytes[0..], expected_hex[0..]) catch unreachable;
+    _ = fmt.hexToBytes(expected_bytes[0..], expected_hex[0..]) catch unreachable;
     testing.expectEqual(actual_bytes, expected_bytes);
 
     // Restore initial state
lib/std/crypto/gimli.zig
@@ -270,7 +270,7 @@ pub fn hash(out: []u8, in: []const u8, options: Hash.Options) void {
 test "hash" {
     // a test vector (30) from NIST KAT submission.
     var msg: [58 / 2]u8 = undefined;
-    try std.fmt.hexToBytes(&msg, "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C");
+    _ = try std.fmt.hexToBytes(&msg, "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C");
     var md: [32]u8 = undefined;
     hash(&md, &msg, .{});
     htest.assertEqual("1C9A03DC6A5DDC5444CFC6F4B154CFF5CF081633B2CEA4D7D0AE7CCFED5AAA44", &md);
@@ -278,7 +278,7 @@ test "hash" {
 
 test "hash test vector 17" {
     var msg: [32 / 2]u8 = undefined;
-    try std.fmt.hexToBytes(&msg, "000102030405060708090A0B0C0D0E0F");
+    _ = try std.fmt.hexToBytes(&msg, "000102030405060708090A0B0C0D0E0F");
     var md: [32]u8 = undefined;
     hash(&md, &msg, .{});
     htest.assertEqual("404C130AF1B9023A7908200919F690FFBB756D5176E056FFDE320016A37C7282", &md);
@@ -286,7 +286,7 @@ test "hash test vector 17" {
 
 test "hash test vector 33" {
     var msg: [32]u8 = undefined;
-    try std.fmt.hexToBytes(&msg, "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F");
+    _ = try std.fmt.hexToBytes(&msg, "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F");
     var md: [32]u8 = undefined;
     hash(&md, &msg, .{});
     htest.assertEqual("A8F4FA28708BDA7EFB4C1914CA4AFA9E475B82D588D36504F87DBB0ED9AB3C4B", &md);
@@ -436,9 +436,9 @@ pub const Aead = struct {
 
 test "cipher" {
     var key: [32]u8 = undefined;
-    try std.fmt.hexToBytes(&key, "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F");
+    _ = try std.fmt.hexToBytes(&key, "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F");
     var nonce: [16]u8 = undefined;
-    try std.fmt.hexToBytes(&nonce, "000102030405060708090A0B0C0D0E0F");
+    _ = try std.fmt.hexToBytes(&nonce, "000102030405060708090A0B0C0D0E0F");
     { // test vector (1) from NIST KAT submission.
         const ad: [0]u8 = undefined;
         const pt: [0]u8 = undefined;
@@ -456,7 +456,7 @@ test "cipher" {
     { // test vector (34) from NIST KAT submission.
         const ad: [0]u8 = undefined;
         var pt: [2 / 2]u8 = undefined;
-        try std.fmt.hexToBytes(&pt, "00");
+        _ = try std.fmt.hexToBytes(&pt, "00");
 
         var ct: [pt.len]u8 = undefined;
         var tag: [16]u8 = undefined;
@@ -470,9 +470,9 @@ test "cipher" {
     }
     { // test vector (106) from NIST KAT submission.
         var ad: [12 / 2]u8 = undefined;
-        try std.fmt.hexToBytes(&ad, "000102030405");
+        _ = try std.fmt.hexToBytes(&ad, "000102030405");
         var pt: [6 / 2]u8 = undefined;
-        try std.fmt.hexToBytes(&pt, "000102");
+        _ = try std.fmt.hexToBytes(&pt, "000102");
 
         var ct: [pt.len]u8 = undefined;
         var tag: [16]u8 = undefined;
@@ -486,9 +486,9 @@ test "cipher" {
     }
     { // test vector (790) from NIST KAT submission.
         var ad: [60 / 2]u8 = undefined;
-        try std.fmt.hexToBytes(&ad, "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D");
+        _ = try std.fmt.hexToBytes(&ad, "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D");
         var pt: [46 / 2]u8 = undefined;
-        try std.fmt.hexToBytes(&pt, "000102030405060708090A0B0C0D0E0F10111213141516");
+        _ = try std.fmt.hexToBytes(&pt, "000102030405060708090A0B0C0D0E0F10111213141516");
 
         var ct: [pt.len]u8 = undefined;
         var tag: [16]u8 = undefined;
@@ -503,7 +503,7 @@ test "cipher" {
     { // test vector (1057) from NIST KAT submission.
         const ad: [0]u8 = undefined;
         var pt: [64 / 2]u8 = undefined;
-        try std.fmt.hexToBytes(&pt, "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F");
+        _ = try std.fmt.hexToBytes(&pt, "000102030405060708090A0B0C0D0E0F101112131415161718191A1B1C1D1E1F");
 
         var ct: [pt.len]u8 = undefined;
         var tag: [16]u8 = undefined;
lib/std/fmt.zig
@@ -1982,23 +1982,34 @@ test "bytes.hex" {
 pub const trim = @compileError("deprecated; use std.mem.trim with std.ascii.spaces instead");
 pub const isWhiteSpace = @compileError("deprecated; use std.ascii.isSpace instead");
 
-pub fn hexToBytes(out: []u8, input: []const u8) !void {
-    if (out.len * 2 < input.len)
+/// Decodes the sequence of bytes represented by the specified string of
+/// hexadecimal characters.
+/// Returns a slice of the output buffer containing the decoded bytes.
+pub fn hexToBytes(out: []u8, input: []const u8) ![]u8 {
+    // Expect 0 or n pairs of hexadecimal digits.
+    if (input.len & 1 != 0)
         return error.InvalidLength;
+    if (out.len * 2 < input.len)
+        return error.NoSpaceLeft;
 
     var in_i: usize = 0;
-    while (in_i != input.len) : (in_i += 2) {
+    while (in_i < input.len) : (in_i += 2) {
         const hi = try charToDigit(input[in_i], 16);
         const lo = try charToDigit(input[in_i + 1], 16);
         out[in_i / 2] = (hi << 4) | lo;
     }
+
+    return out[0 .. in_i / 2];
 }
 
 test "hexToBytes" {
-    const test_hex_str = "909A312BB12ED1F819B3521AC4C1E896F2160507FFC1C8381E3B07BB16BD1706";
-    var pb: [32]u8 = undefined;
-    try hexToBytes(pb[0..], test_hex_str);
-    try expectFmt(test_hex_str, "{X}", .{pb});
+    var buf: [32]u8 = undefined;
+    try expectFmt("90" ** 32, "{X}", .{try hexToBytes(&buf, "90" ** 32)});
+    try expectFmt("ABCD", "{X}", .{try hexToBytes(&buf, "ABCD")});
+    try expectFmt("", "{X}", .{try hexToBytes(&buf, "")});
+    std.testing.expectError(error.InvalidCharacter, hexToBytes(&buf, "012Z"));
+    std.testing.expectError(error.InvalidLength, hexToBytes(&buf, "AAA"));
+    std.testing.expectError(error.NoSpaceLeft, hexToBytes(buf[0..1], "ABAB"));
 }
 
 test "formatIntValue with comptime_int" {
src/Cache.zig
@@ -317,7 +317,7 @@ pub const Manifest = struct {
             cache_hash_file.stat.size = fmt.parseInt(u64, size, 10) catch return error.InvalidFormat;
             cache_hash_file.stat.inode = fmt.parseInt(fs.File.INode, inode, 10) catch return error.InvalidFormat;
             cache_hash_file.stat.mtime = fmt.parseInt(i64, mtime_nsec_str, 10) catch return error.InvalidFormat;
-            std.fmt.hexToBytes(&cache_hash_file.bin_digest, digest_str) catch return error.InvalidFormat;
+            _ = std.fmt.hexToBytes(&cache_hash_file.bin_digest, digest_str) catch return error.InvalidFormat;
 
             if (file_path.len == 0) {
                 return error.InvalidFormat;