--- /dev/null
+
+# HG changeset patch
+# User Dennis Jackson <djackson@mozilla.com>
+# Date 1637577642 0
+# Node ID dea71cbef9e03636f37c6cb120f8deccce6e17dd
+# Parent da3d22d708c9cc0a32cff339658aeb627575e371
+Bug 1737470 - Ensure DER encoded signatures are within size limits. r=jschanck,mt,bbeurdouche,rrelyea
+
+Differential Revision: https://phabricator.services.mozilla.com/D129514
+
+--- a/nss/lib/cryptohi/secvfy.c
++++ b/nss/lib/cryptohi/secvfy.c
+@@ -164,6 +164,37 @@ verifyPKCS1DigestInfo(const VFYContext *
+ PR_FALSE /*XXX: unsafeAllowMissingParameters*/);
+ }
+
++static unsigned int
++checkedSignatureLen(const SECKEYPublicKey *pubk)
++{
++ unsigned int sigLen = SECKEY_SignatureLen(pubk);
++ if (sigLen == 0) {
++ /* Error set by SECKEY_SignatureLen */
++ return sigLen;
++ }
++ unsigned int maxSigLen;
++ switch (pubk->keyType) {
++ case rsaKey:
++ case rsaPssKey:
++ maxSigLen = (RSA_MAX_MODULUS_BITS + 7) / 8;
++ break;
++ case dsaKey:
++ maxSigLen = DSA_MAX_SIGNATURE_LEN;
++ break;
++ case ecKey:
++ maxSigLen = 2 * MAX_ECKEY_LEN;
++ break;
++ default:
++ PORT_SetError(SEC_ERROR_UNSUPPORTED_KEYALG);
++ return 0;
++ }
++ if (sigLen > maxSigLen) {
++ PORT_SetError(SEC_ERROR_INVALID_KEY);
++ return 0;
++ }
++ return sigLen;
++}
++
+ /*
+ * decode the ECDSA or DSA signature from it's DER wrapping.
+ * The unwrapped/raw signature is placed in the buffer pointed
+@@ -174,38 +205,38 @@ decodeECorDSASignature(SECOidTag algid,
+ unsigned int len)
+ {
+ SECItem *dsasig = NULL; /* also used for ECDSA */
+- SECStatus rv = SECSuccess;
+
+- if ((algid != SEC_OID_ANSIX9_DSA_SIGNATURE) &&
+- (algid != SEC_OID_ANSIX962_EC_PUBLIC_KEY)) {
+- if (sig->len != len) {
+- PORT_SetError(SEC_ERROR_BAD_DER);
+- return SECFailure;
++ /* Safety: Ensure algId is as expected and that signature size is within maxmimums */
++ if (algid == SEC_OID_ANSIX9_DSA_SIGNATURE) {
++ if (len > DSA_MAX_SIGNATURE_LEN) {
++ goto loser;
+ }
+-
+- PORT_Memcpy(dsig, sig->data, sig->len);
+- return SECSuccess;
+- }
+-
+- if (algid == SEC_OID_ANSIX962_EC_PUBLIC_KEY) {
++ } else if (algid == SEC_OID_ANSIX962_EC_PUBLIC_KEY) {
+ if (len > MAX_ECKEY_LEN * 2) {
+- PORT_SetError(SEC_ERROR_BAD_DER);
+- return SECFailure;
++ goto loser;
+ }
+- }
+- dsasig = DSAU_DecodeDerSigToLen((SECItem *)sig, len);
+-
+- if ((dsasig == NULL) || (dsasig->len != len)) {
+- rv = SECFailure;
+ } else {
+- PORT_Memcpy(dsig, dsasig->data, dsasig->len);
++ goto loser;
+ }
+
+- if (dsasig != NULL)
++ /* Decode and pad to length */
++ dsasig = DSAU_DecodeDerSigToLen((SECItem *)sig, len);
++ if (dsasig == NULL) {
++ goto loser;
++ }
++ if (dsasig->len != len) {
+ SECITEM_FreeItem(dsasig, PR_TRUE);
+- if (rv == SECFailure)
+- PORT_SetError(SEC_ERROR_BAD_DER);
+- return rv;
++ goto loser;
++ }
++
++ PORT_Memcpy(dsig, dsasig->data, len);
++ SECITEM_FreeItem(dsasig, PR_TRUE);
++
++ return SECSuccess;
++
++loser:
++ PORT_SetError(SEC_ERROR_BAD_DER);
++ return SECFailure;
+ }
+
+ const SEC_ASN1Template hashParameterTemplate[] =
+@@ -231,7 +262,7 @@ SECStatus
+ sec_DecodeSigAlg(const SECKEYPublicKey *key, SECOidTag sigAlg,
+ const SECItem *param, SECOidTag *encalg, SECOidTag *hashalg)
+ {
+- int len;
++ unsigned int len;
+ PLArenaPool *arena;
+ SECStatus rv;
+ SECItem oid;
+@@ -446,48 +477,52 @@ vfy_CreateContext(const SECKEYPublicKey
+ cx->pkcs1RSADigestInfo = NULL;
+ rv = SECSuccess;
+ if (sig) {
+- switch (type) {
+- case rsaKey:
+- rv = recoverPKCS1DigestInfo(hashAlg, &cx->hashAlg,
+- &cx->pkcs1RSADigestInfo,
+- &cx->pkcs1RSADigestInfoLen,
+- cx->key,
+- sig, wincx);
+- break;
+- case rsaPssKey:
+- sigLen = SECKEY_SignatureLen(key);
+- if (sigLen == 0) {
+- /* error set by SECKEY_SignatureLen */
+- rv = SECFailure;
++ rv = SECFailure;
++ if (type == rsaKey) {
++ rv = recoverPKCS1DigestInfo(hashAlg, &cx->hashAlg,
++ &cx->pkcs1RSADigestInfo,
++ &cx->pkcs1RSADigestInfoLen,
++ cx->key,
++ sig, wincx);
++ } else {
++ sigLen = checkedSignatureLen(key);
++ /* Check signature length is within limits */
++ if (sigLen == 0) {
++ /* error set by checkedSignatureLen */
++ rv = SECFailure;
++ goto loser;
++ }
++ if (sigLen > sizeof(cx->u)) {
++ PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
++ rv = SECFailure;
++ goto loser;
++ }
++ switch (type) {
++ case rsaPssKey:
++ if (sig->len != sigLen) {
++ PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
++ rv = SECFailure;
++ goto loser;
++ }
++ PORT_Memcpy(cx->u.buffer, sig->data, sigLen);
++ rv = SECSuccess;
+ break;
+- }
+- if (sig->len != sigLen) {
+- PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
+- rv = SECFailure;
++ case ecKey:
++ case dsaKey:
++ /* decodeECorDSASignature will check sigLen == sig->len after padding */
++ rv = decodeECorDSASignature(encAlg, sig, cx->u.buffer, sigLen);
+ break;
+- }
+- PORT_Memcpy(cx->u.buffer, sig->data, sigLen);
+- break;
+- case dsaKey:
+- case ecKey:
+- sigLen = SECKEY_SignatureLen(key);
+- if (sigLen == 0) {
+- /* error set by SECKEY_SignatureLen */
++ default:
++ /* Unreachable */
+ rv = SECFailure;
+- break;
+- }
+- rv = decodeECorDSASignature(encAlg, sig, cx->u.buffer, sigLen);
+- break;
+- default:
+- rv = SECFailure;
+- PORT_SetError(SEC_ERROR_UNSUPPORTED_KEYALG);
+- break;
++ goto loser;
++ }
++ }
++ if (rv != SECSuccess) {
++ goto loser;
+ }
+ }
+
+- if (rv)
+- goto loser;
+-
+ /* check hash alg again, RSA may have changed it.*/
+ if (HASH_GetHashTypeByOidTag(cx->hashAlg) == HASH_AlgNULL) {
+ /* error set by HASH_GetHashTypeByOidTag */
+@@ -622,11 +657,16 @@ VFY_EndWithSignature(VFYContext *cx, SEC
+ switch (cx->key->keyType) {
+ case ecKey:
+ case dsaKey:
+- dsasig.data = cx->u.buffer;
+- dsasig.len = SECKEY_SignatureLen(cx->key);
++ dsasig.len = checkedSignatureLen(cx->key);
+ if (dsasig.len == 0) {
+ return SECFailure;
+ }
++ if (dsasig.len > sizeof(cx->u)) {
++ PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
++ return SECFailure;
++ }
++ dsasig.data = cx->u.buffer;
++
+ if (sig) {
+ rv = decodeECorDSASignature(cx->encAlg, sig, dsasig.data,
+ dsasig.len);
+@@ -658,8 +698,13 @@ VFY_EndWithSignature(VFYContext *cx, SEC
+ }
+
+ rsasig.data = cx->u.buffer;
+- rsasig.len = SECKEY_SignatureLen(cx->key);
++ rsasig.len = checkedSignatureLen(cx->key);
+ if (rsasig.len == 0) {
++ /* Error set by checkedSignatureLen */
++ return SECFailure;
++ }
++ if (rsasig.len > sizeof(cx->u)) {
++ PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
+ return SECFailure;
+ }
+ if (sig) {
+@@ -721,7 +766,6 @@ vfy_VerifyDigest(const SECItem *digest,
+ SECStatus rv;
+ VFYContext *cx;
+ SECItem dsasig; /* also used for ECDSA */
+-
+ rv = SECFailure;
+
+ cx = vfy_CreateContext(key, sig, encAlg, hashAlg, NULL, wincx);
+@@ -729,19 +773,25 @@ vfy_VerifyDigest(const SECItem *digest,
+ switch (key->keyType) {
+ case rsaKey:
+ rv = verifyPKCS1DigestInfo(cx, digest);
++ /* Error (if any) set by verifyPKCS1DigestInfo */
+ break;
+- case dsaKey:
+ case ecKey:
++ case dsaKey:
+ dsasig.data = cx->u.buffer;
+- dsasig.len = SECKEY_SignatureLen(cx->key);
++ dsasig.len = checkedSignatureLen(cx->key);
+ if (dsasig.len == 0) {
++ /* Error set by checkedSignatureLen */
++ rv = SECFailure;
+ break;
+ }
+- if (PK11_Verify(cx->key, &dsasig, (SECItem *)digest, cx->wincx) !=
+- SECSuccess) {
++ if (dsasig.len > sizeof(cx->u)) {
++ PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
++ rv = SECFailure;
++ break;
++ }
++ rv = PK11_Verify(cx->key, &dsasig, (SECItem *)digest, cx->wincx);
++ if (rv != SECSuccess) {
+ PORT_SetError(SEC_ERROR_BAD_SIGNATURE);
+- } else {
+- rv = SECSuccess;
+ }
+ break;
+ default:
+
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