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Fix buffer overrun on a partial block in the C reference functions #179

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Fix buffer overrun on a partial block in the C reference functions #179

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4 changes: 4 additions & 0 deletions cmp/src/ref.c
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@ static const u8 values[256] = {
void SUFFIX(encode_seq, COMPILER)
(u8 const* restrict input, usize len, u8* restrict output)
{
len -= len % 3;
for (; len; len -= 3) {
*output++ = symbols[(u8)(input[0] >> 2)];
*output++ = symbols[(u8)(input[0] << 4 | input[1] >> 4)];
Expand All @@ -46,6 +47,7 @@ void SUFFIX(encode_seq, COMPILER)
void SUFFIX(encode_par, COMPILER)
(u8 const* restrict input, usize len, u8* restrict output)
{
len -= len % 3;
for (; len; len -= 3) {
u64 x = (u64)input[0] << 16 | (u64)input[1] << 8 | input[2];
output[0] = symbols[(u8)(x >> 18)];
Expand All @@ -60,6 +62,7 @@ void SUFFIX(encode_par, COMPILER)
i32 SUFFIX(decode_seq, COMPILER)
(u8 const* restrict input, usize len, u8* restrict output)
{
len -= len % 4;
for (; len; len -= 4) {
if (values[input[0]] >= 64) return -1;
if (values[input[1]] >= 64) return -1;
Expand All @@ -76,6 +79,7 @@ i32 SUFFIX(decode_seq, COMPILER)
i32 SUFFIX(decode_par, COMPILER)
(u8 const* restrict input, usize len, u8* restrict output)
{
len -= len % 4;
for (; len; len -= 4) {
if (values[input[0]] & values[input[1]] & values[input[2]]
& values[input[3]] & 0xc0) {
Expand Down
36 changes: 36 additions & 0 deletions cmp/tests/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -54,3 +54,39 @@ fn difference() {
assert_eq!(BASE64.decode(x).unwrap(), vec![0, 0]);
assert_eq!(BASE64_STANDARD.decode(x).err().unwrap(), InvalidByte(2, b'='));
}

#[test]
fn partial_block() {
let encode = &[
(b"f" as &[u8], b"" as &[u8]),
(b"fo" as &[u8], b"" as &[u8]),
(b"foob" as &[u8], b"Zm9v" as &[u8]),
(b"fooba" as &[u8], b"Zm9v" as &[u8]),
];
for &(ref i, ref o) in encode {
let mut r = vec![0u8; o.len()];
cmp::base64_encode_seq_gcc(i, &mut r);
assert_eq!(&r, o);
}
for &(ref i, ref o) in encode {
let mut r = vec![0u8; o.len()];
cmp::base64_encode_par_gcc(i, &mut r);
assert_eq!(&r, o);
}
let decode = &[
(b"Z" as &[u8], b"" as &[u8]),
(b"Zm9" as &[u8], b"" as &[u8]),
(b"Zm9vY" as &[u8], b"foo" as &[u8]),
(b"Zm9vYmF" as &[u8], b"foo" as &[u8]),
];
for &(ref i, ref o) in decode {
let mut r = vec![0u8; o.len()];
assert_eq!(cmp::base64_decode_seq_gcc(i, &mut r), Ok(()));
assert_eq!(&r, o);
}
for &(ref i, ref o) in decode {
let mut r = vec![0u8; o.len()];
assert_eq!(cmp::base64_decode_par_gcc(i, &mut r), Ok(()));
assert_eq!(&r, o);
}
}