Fix ERR_GET_REASON checks.

Reason codes across libraries may collide. One must never check
ERR_GET_REASON without also checking ERR_GET_LIB.

Change-Id: I0b58ce27a5571ab173d231c1a673bce1cf0427aa
Reviewed-on: https://boringssl-review.googlesource.com/32110
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
Reviewed-by: Adam Langley <alangley@gmail.com>

crypto/asn1/a_d2i_fp.c

diff --git a/crypto/asn1/a_d2i_fp.c b/crypto/asn1/a_d2i_fp.c
index 50779d2..ee71ee9 100644
--- a/crypto/asn1/a_d2i_fp.c
+++ b/crypto/asn1/a_d2i_fp.c
@@ -197,13 +197,12 @@
         c.inf = ASN1_get_object(&(c.p), &(c.slen), &(c.tag), &(c.xclass),
                                 len - off);
         if (c.inf & 0x80) {
-            uint32_t e;
-
-            e = ERR_GET_REASON(ERR_peek_error());
-            if (e != ASN1_R_TOO_LONG)
+            uint32_t error = ERR_peek_error();
+            if (ERR_GET_LIB(error) != ERR_LIB_ASN1 ||
+                ERR_GET_REASON(error) != ASN1_R_TOO_LONG) {
                 goto err;
-            else
-                ERR_clear_error(); /* clear error */
+            }
+            ERR_clear_error();
         }
         i = c.p - p;            /* header length */
         off += i;               /* end of data */

crypto/pem/pem_info.c

diff --git a/crypto/pem/pem_info.c b/crypto/pem/pem_info.c
index ba29b83..7ed8aee 100644
--- a/crypto/pem/pem_info.c
+++ b/crypto/pem/pem_info.c
@@ -94,7 +94,7 @@
     void *pp;
     unsigned char *data = NULL;
     const unsigned char *p;
-    long len, error = 0;
+    long len;
     int ok = 0;
     STACK_OF(X509_INFO) *ret = NULL;
     unsigned int i, raw, ptype;
@@ -115,8 +115,9 @@
         ptype = 0;
         i = PEM_read_bio(bp, &name, &header, &data, &len);
         if (i == 0) {
-            error = ERR_GET_REASON(ERR_peek_last_error());
-            if (error == PEM_R_NO_START_LINE) {
+            uint32_t error = ERR_peek_last_error();
+            if (ERR_GET_LIB(error) == ERR_LIB_PEM &&
+                ERR_GET_REASON(error) == PEM_R_NO_START_LINE) {
                 ERR_clear_error();
                 break;
             }

crypto/pem/pem_lib.c

diff --git a/crypto/pem/pem_lib.c b/crypto/pem/pem_lib.c
index 759c5d7..c682429 100644
--- a/crypto/pem/pem_lib.c
+++ b/crypto/pem/pem_lib.c
@@ -217,8 +217,11 @@
 
     for (;;) {
         if (!PEM_read_bio(bp, &nm, &header, &data, &len)) {
-            if (ERR_GET_REASON(ERR_peek_error()) == PEM_R_NO_START_LINE)
+            uint32_t error = ERR_peek_error();
+            if (ERR_GET_LIB(error) == ERR_LIB_PEM &&
+                ERR_GET_REASON(error) == PEM_R_NO_START_LINE) {
                 ERR_add_error_data(2, "Expecting: ", name);
+            }
             return 0;
         }
         if (check_pem(nm, name))

crypto/x509/by_file.c

diff --git a/crypto/x509/by_file.c b/crypto/x509/by_file.c
index 555cb85..dfff425 100644
--- a/crypto/x509/by_file.c
+++ b/crypto/x509/by_file.c
@@ -138,14 +138,15 @@
         for (;;) {
             x = PEM_read_bio_X509_AUX(in, NULL, NULL, NULL);
             if (x == NULL) {
-                if ((ERR_GET_REASON(ERR_peek_last_error()) ==
-                     PEM_R_NO_START_LINE) && (count > 0)) {
+                uint32_t error = ERR_peek_last_error();
+                if (ERR_GET_LIB(error) == ERR_LIB_PEM &&
+                    ERR_GET_REASON(error) == PEM_R_NO_START_LINE &&
+                    count > 0) {
                     ERR_clear_error();
                     break;
-                } else {
-                    OPENSSL_PUT_ERROR(X509, ERR_R_PEM_LIB);
-                    goto err;
                 }
+                OPENSSL_PUT_ERROR(X509, ERR_R_PEM_LIB);
+                goto err;
             }
             i = X509_STORE_add_cert(ctx->store_ctx, x);
             if (!i)
@@ -197,14 +198,15 @@
         for (;;) {
             x = PEM_read_bio_X509_CRL(in, NULL, NULL, NULL);
             if (x == NULL) {
-                if ((ERR_GET_REASON(ERR_peek_last_error()) ==
-                     PEM_R_NO_START_LINE) && (count > 0)) {
+                uint32_t error = ERR_peek_last_error();
+                if (ERR_GET_LIB(error) == ERR_LIB_PEM &&
+                    ERR_GET_REASON(error) == PEM_R_NO_START_LINE &&
+                    count > 0) {
                     ERR_clear_error();
                     break;
-                } else {
-                    OPENSSL_PUT_ERROR(X509, ERR_R_PEM_LIB);
-                    goto err;
                 }
+                OPENSSL_PUT_ERROR(X509, ERR_R_PEM_LIB);
+                goto err;
             }
             i = X509_STORE_add_crl(ctx->store_ctx, x);
             if (!i)