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Increase base64 decoding table size to 256, preventing out of bounds reads

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Franz Hoeltermann
2025-11-22 12:54:36 +01:00
parent adcbfb7861
commit cd4bec0007
1 changed files with 35 additions and 19 deletions
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54
core/encoding/base64/base64.odin
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@@ -26,23 +26,39 @@ ENC_TABLE := [64]byte {
PADDING :: '='
DEC_TABLE := [128]int {
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, 62, -1, -1, -1, 63,
DEC_TABLE := [256]u8 {
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 62, 0, 0, 0, 63,
52, 53, 54, 55, 56, 57, 58, 59,
60, 61, -1, -1, -1, -1, -1, -1,
-1, 0, 1, 2, 3, 4, 5, 6,
60, 61, 0, 0, 0, 0, 0, 0,
0, 0, 1, 2, 3, 4, 5, 6,
7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22,
23, 24, 25, -1, -1, -1, -1, -1,
-1, 26, 27, 28, 29, 30, 31, 32,
23, 24, 25, 0, 0, 0, 0, 0,
0, 26, 27, 28, 29, 30, 31, 32,
33, 34, 35, 36, 37, 38, 39, 40,
41, 42, 43, 44, 45, 46, 47, 48,
49, 50, 51, -1, -1, -1, -1, -1,
49, 50, 51, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
}
encode :: proc(data: []byte, ENC_TBL := ENC_TABLE, allocator := context.allocator) -> (encoded: string, err: mem.Allocator_Error) #optional_allocator_error {
@@ -120,10 +136,10 @@ decode_into :: proc(w: io.Writer, data: string, DEC_TBL := DEC_TABLE) -> io.Erro
i, j: int
for ; j + 3 <= length; i, j = i + 4, j + 3 {
#no_bounds_check {
c0 = DEC_TBL[data[i]]
c1 = DEC_TBL[data[i + 1]]
c2 = DEC_TBL[data[i + 2]]
c3 = DEC_TBL[data[i + 3]]
c0 = int(DEC_TBL[data[i]])
c1 = int(DEC_TBL[data[i + 1]])
c2 = int(DEC_TBL[data[i + 2]])
c3 = int(DEC_TBL[data[i + 3]])
b0 = (c0 << 2) | (c1 >> 4)
b1 = (c1 << 4) | (c2 >> 2)
@@ -140,9 +156,9 @@ decode_into :: proc(w: io.Writer, data: string, DEC_TBL := DEC_TABLE) -> io.Erro
rest := length - j
if rest > 0 {
#no_bounds_check {
c0 = DEC_TBL[data[i]]
c1 = DEC_TBL[data[i + 1]]
c2 = DEC_TBL[data[i + 2]]
c0 = int(DEC_TBL[data[i]])
c1 = int(DEC_TBL[data[i + 1]])
c2 = int(DEC_TBL[data[i + 2]])
b0 = (c0 << 2) | (c1 >> 4)
b1 = (c1 << 4) | (c2 >> 2)