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fix F-3085 "Base64_Decode silently returns success with outLen=0 when input is a 1-3 byte truncated base64 fragment, violating decode(encode(x)) roundtrip for inputs producing 2-3 base64 chars without padding"

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wolfcrypt/src/coding.c: in Base64_Decode() and Base64_Decode_nonCT(), check for non-whitespace characters past the end and return ASN_INPUT_E if found;

wolfcrypt/test/test.c: in base64_test(), remove ';' from goodChar[], and add trailing*[] test strings and N_BYTE_TRAILING_TEST(), for positive and negative testing of new checks.
This commit is contained in:
Daniel Pouzzner
2026-06-29 23:48:36 -05:00
parent 6560777d05
commit 2af2a2967f
2 changed files with 86 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files
wolfcrypt/src/coding.c
+52 -10
View File
@@ -192,6 +192,7 @@ int Base64_Decode_nonCT(const byte* in, word32 inLen, byte* out, word32* outLen)
}
e1 = in[j++];
if (e1 == '\0') {
inLen = 0;
break;
}
inLen--;
@@ -230,11 +231,6 @@ int Base64_Decode_nonCT(const byte* in, word32 inLen, byte* out, word32* outLen)
return ASN_INPUT_E;
}
if (i + 1 + !pad3 + !pad4 > *outLen) {
WOLFSSL_MSG("Bad Base64 Decode out buffer, too small");
return BUFFER_E;
}
e1 = Base64_Char2Val_by_table(e1);
e2 = Base64_Char2Val_by_table(e2);
e3 = (byte)((e3 == PAD) ? 0 : Base64_Char2Val_by_table(e3));
@@ -245,6 +241,11 @@ int Base64_Decode_nonCT(const byte* in, word32 inLen, byte* out, word32* outLen)
return ASN_INPUT_E;
}
if (i + 1 + !pad3 + !pad4 > *outLen) {
WOLFSSL_MSG("Bad Base64 Decode out buffer, too small");
return BUFFER_E;
}
b1 = (byte)((e1 << 2) | (e2 >> 4));
b2 = (byte)(((e2 & 0xF) << 4) | (e3 >> 2));
b3 = (byte)(((e3 & 0x3) << 6) | e4);
@@ -258,6 +259,24 @@ int Base64_Decode_nonCT(const byte* in, word32 inLen, byte* out, word32* outLen)
break;
}
/* If there is still input available, and it's not whitespace or nulls, then
* the input is invalid.
*/
while (inLen > 0) {
word32 cur_j = j;
if (in[j] == 0)
break;
if ((ret = Base64_SkipNewline(in, &inLen, &j)) != 0) {
if (ret == WC_NO_ERR_TRACE(BUFFER_E)) {
/* Running out of buffer here is not an error */
break;
}
return ret;
}
if (j == cur_j)
return ASN_INPUT_E;
}
/* If the output buffer has a room for an extra byte, add a null terminator */
if (out && *outLen > i)
out[i]= '\0';
@@ -294,6 +313,7 @@ int Base64_Decode(const byte* in, word32 inLen, byte* out, word32* outLen)
}
e1 = in[j++];
if (e1 == '\0') {
inLen = 0;
break;
}
inLen--;
@@ -321,11 +341,6 @@ int Base64_Decode(const byte* in, word32 inLen, byte* out, word32* outLen)
if (pad3 && !pad4)
return ASN_INPUT_E;
if (i + 1 + !pad3 + !pad4 > *outLen) {
WOLFSSL_MSG("Bad Base64 Decode out buffer, too small");
return BUFFER_E;
}
e1 = Base64_Char2Val_CT(e1);
e2 = Base64_Char2Val_CT(e2);
e3 = (byte)((e3 == PAD) ? 0 : Base64_Char2Val_CT(e3));
@@ -336,6 +351,15 @@ int Base64_Decode(const byte* in, word32 inLen, byte* out, word32* outLen)
return ASN_INPUT_E;
}
/* Output space check needs to follow input character validation to
* assure ASN_INPUT_E is returned on truncated input with the
* terminating null included in the input buffer.
*/
if (i + 1 + !pad3 + !pad4 > *outLen) {
WOLFSSL_MSG("Bad Base64 Decode out buffer, too small");
return BUFFER_E;
}
b1 = (byte)((e1 << 2) | (e2 >> 4));
b2 = (byte)(((e2 & 0xF) << 4) | (e3 >> 2));
b3 = (byte)(((e3 & 0x3) << 6) | e4);
@@ -349,6 +373,24 @@ int Base64_Decode(const byte* in, word32 inLen, byte* out, word32* outLen)
break;
}
/* If there is still input available, and it's not whitespace or nulls, then
* the input is invalid.
*/
while (inLen > 0) {
word32 cur_j = j;
if (in[j] == 0)
break;
if ((ret = Base64_SkipNewline(in, &inLen, &j)) != 0) {
if (ret == WC_NO_ERR_TRACE(BUFFER_E)) {
/* Running out of buffer here is not an error */
break;
}
return ret;
}
if (j == cur_j)
return ASN_INPUT_E;
}
/* If the output buffer has a room for an extra byte, add a null terminator */
if (out && *outLen > i)
out[i]= '\0';
wolfcrypt/test/test.c
+34 -1
View File
@@ -4130,12 +4130,18 @@ WOLFSSL_TEST_SUBROUTINE wc_test_ret_t base64_test(void)
static const byte goodChar[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/;";
"0123456789+/";
static const byte charTest[] = "A+Gd\0\0\0";
static const byte oneByteTest[] = "YQ==";
static const byte twoByteTest[] = "YWE=";
static const byte threeByteTest[] = "YWFh";
static const byte fourByteTest[] = "YWFhYQ==";
static const byte trailingLFTest[] = "YWFhYQ==\n\n";
static const byte trailingSpaceTest[] = "YWFhYQ== ";
static const byte trailingCodesTest1[] = "YWFhY";
static const byte trailingCodesTest2[] = "YWFhYW";
static const byte trailingCodesTest3[] = "YWFhYWF";
static const byte trailingJunkTest[] = "YWFhYQ==X";
static const byte byteTestOutput[] = "aaaa";
int i;
WOLFSSL_ENTER("base64_test");
@@ -4255,6 +4261,26 @@ WOLFSSL_TEST_SUBROUTINE wc_test_ret_t base64_test(void)
N_BYTE_TEST(Base64_Decode, 3, threeByteTest);
N_BYTE_TEST(Base64_Decode, 4, fourByteTest);
#define N_BYTE_TRAILING_TEST(f, n, t, e) do { \
outLen = (n); \
ret = (f)(t, sizeof(t), out, &outLen); \
if (ret != (e)) \
return WC_TEST_RET_ENC_EC(ret); \
else if (ret == 0) { \
if (outLen != (n)) \
return WC_TEST_RET_ENC_I(outLen); \
if (XMEMCMP(out, byteTestOutput, n) != 0) \
return WC_TEST_RET_ENC_NC; \
} \
} while (0)
N_BYTE_TRAILING_TEST(Base64_Decode, 4, trailingLFTest, 0);
N_BYTE_TRAILING_TEST(Base64_Decode, 4, trailingSpaceTest, 0);
N_BYTE_TRAILING_TEST(Base64_Decode, 4, trailingCodesTest1, WC_NO_ERR_TRACE(ASN_INPUT_E));
N_BYTE_TRAILING_TEST(Base64_Decode, 4, trailingCodesTest2, WC_NO_ERR_TRACE(ASN_INPUT_E));
N_BYTE_TRAILING_TEST(Base64_Decode, 4, trailingCodesTest3, WC_NO_ERR_TRACE(ASN_INPUT_E));
N_BYTE_TRAILING_TEST(Base64_Decode, 4, trailingJunkTest, WC_NO_ERR_TRACE(ASN_INPUT_E));
/* Same tests again, using Base64_Decode_nonCT() */
/* Good Base64 encodings. */
@@ -4335,6 +4361,13 @@ WOLFSSL_TEST_SUBROUTINE wc_test_ret_t base64_test(void)
N_BYTE_TEST(Base64_Decode_nonCT, 3, threeByteTest);
N_BYTE_TEST(Base64_Decode_nonCT, 4, fourByteTest);
N_BYTE_TRAILING_TEST(Base64_Decode_nonCT, 4, trailingLFTest, 0);
N_BYTE_TRAILING_TEST(Base64_Decode_nonCT, 4, trailingSpaceTest, 0);
N_BYTE_TRAILING_TEST(Base64_Decode_nonCT, 4, trailingCodesTest1, WC_NO_ERR_TRACE(ASN_INPUT_E));
N_BYTE_TRAILING_TEST(Base64_Decode_nonCT, 4, trailingCodesTest2, WC_NO_ERR_TRACE(ASN_INPUT_E));
N_BYTE_TRAILING_TEST(Base64_Decode_nonCT, 4, trailingCodesTest3, WC_NO_ERR_TRACE(ASN_INPUT_E));
N_BYTE_TRAILING_TEST(Base64_Decode_nonCT, 4, trailingJunkTest, WC_NO_ERR_TRACE(ASN_INPUT_E));
#ifdef WOLFSSL_BASE64_ENCODE
/* Decode and encode all symbols - non-alphanumeric. */
dataLen = sizeof(data);