Fix String References

1. Modify GetStringAlloc() to also take the string length as provided by
   GetUint32().
2. New use of GetStringAlloc() was misusing the heap. Fix using the
   updated GetStringAlloc() function.

Author: ejohnstown

src/internal.c

@@ -3599,7 +3599,8 @@ int GetString(char* s, word32* sSz, const byte* buf, word32 len, word32 *idx)
 
 /* Gets the size of a string, allocates memory to hold it plus a NULL, then
  * copies it into the allocated buffer, and terminates it with a NULL. */
-int GetStringAlloc(void* heap, char** s, const byte* buf, word32 len, word32 *idx)
+int GetStringAlloc(void* heap, char** s, word32* sSz,
+        const byte* buf, word32 len, word32 *idx)
 {
     int result;
     const byte *str;
@@ -3617,9 +3618,14 @@ int GetStringAlloc(void* heap, char** s, const byte* buf, word32 len, word32 *id
             WMEMCPY(newStr, str, strSz);
         newStr[strSz] = 0;
 
-        if (*s != NULL)
-            WFREE(*s, heap, DYNTYPE_STRING);
-        *s = newStr;
+        if (s != NULL) {
+            if (*s != NULL)
+                WFREE(*s, heap, DYNTYPE_STRING);
+            *s = newStr;
+            if (sSz != NULL) {
+                *sSz = strSz;
+            }
+        }
     }
 
     return result;
@@ -8184,14 +8190,15 @@ static int DoUserAuthInfoRequest(WOLFSSH* ssh, byte* buf, word32 len,
 
     if (ret == WS_SUCCESS) {
         begin = *idx;
-        ret = GetStringAlloc(heap, (char**)&authName, buf, len, &begin);
+        ret = GetStringAlloc(heap, (char**)&authName, NULL, buf, len, &begin);
     }
 
     if (ret == WS_SUCCESS)
-        ret = GetStringAlloc(heap, (char**)&authInstruction, buf, len, &begin);
+        ret = GetStringAlloc(heap, (char**)&authInstruction, NULL,
+                buf, len, &begin);
 
     if (ret == WS_SUCCESS)
-        ret = GetStringAlloc(heap, (char**)&language, buf, len, &begin);
+        ret = GetStringAlloc(heap, (char**)&language, NULL, buf, len, &begin);
 
     if (ret == WS_SUCCESS)
         ret = GetUint32(&promptSz, buf, len, &begin);
@@ -8218,7 +8225,7 @@ static int DoUserAuthInfoRequest(WOLFSSH* ssh, byte* buf, word32 len,
         } else {
             WMEMSET(echo, 0, sizeof(byte) * promptSz);
             for (entry = 0; entry < promptSz; entry++) {
-                ret = GetStringAlloc(heap, (char**)&prompts[entry],
+                ret = GetStringAlloc(heap, (char**)&prompts[entry], NULL,
                                      buf, len, &begin);
                 if (ret != WS_SUCCESS)
                     break;
@@ -8283,7 +8290,7 @@ static int DoGlobalRequestFwd(WOLFSSH* ssh,
     if (ret == WS_SUCCESS) {
         begin = *idx;
         WLOG(WS_LOG_INFO, "wantReply = %d, isCancel = %d", wantReply, isCancel);
-        ret = GetStringAlloc(ssh->ctx->heap, &bindAddr, buf, len, &begin);
+        ret = GetStringAlloc(ssh->ctx->heap, &bindAddr, NULL, buf, len, &begin);
     }
 
     if (ret == WS_SUCCESS) {
@@ -8398,14 +8405,14 @@ static int DoChannelOpenForward(WOLFSSH* ssh,
 
     if (ret == WS_SUCCESS) {
         begin = *idx;
-        ret = GetStringAlloc(ssh->ctx->heap, host, buf, len, &begin);
+        ret = GetStringAlloc(ssh->ctx->heap, host, NULL, buf, len, &begin);
     }
 
     if (ret == WS_SUCCESS)
         ret = GetUint32(hostPort, buf, len, &begin);
 
     if (ret == WS_SUCCESS)
-        ret = GetStringAlloc(ssh->ctx->heap, origin, buf, len, &begin);
+        ret = GetStringAlloc(ssh->ctx->heap, origin, NULL, buf, len, &begin);
 
     if (ret == WS_SUCCESS)
         ret = GetUint32(originPort, buf, len, &begin);
@@ -9113,7 +9120,7 @@ static int DoChannelRequest(WOLFSSH* ssh,
             ssh->clientState = CLIENT_DONE;
         }
         else if (WSTRNCMP(type, "exec", typeSz) == 0) {
-            ret = GetStringAlloc(ssh->ctx->heap, &channel->command,
+            ret = GetStringAlloc(ssh->ctx->heap, &channel->command, NULL,
                     buf, len, &begin);
             channel->sessionType = WOLFSSH_SESSION_EXEC;
             if (ssh->ctx->channelReqExecCb) {
@@ -9124,7 +9131,7 @@ static int DoChannelRequest(WOLFSSH* ssh,
             WLOG(WS_LOG_DEBUG, "  command = %s", channel->command);
         }
         else if (WSTRNCMP(type, "subsystem", typeSz) == 0) {
-            ret = GetStringAlloc(ssh->ctx->heap, &channel->command,
+            ret = GetStringAlloc(ssh->ctx->heap, &channel->command, NULL,
                     buf, len, &begin);
             channel->sessionType = WOLFSSH_SESSION_SUBSYSTEM;
             if (ssh->ctx->channelReqSubsysCb) {
@@ -9153,7 +9160,8 @@ static int DoChannelRequest(WOLFSSH* ssh,
             if (ret == WS_SUCCESS)
                 ret = GetUint32(&heightPixels, buf, len, &begin);
             if (ret == WS_SUCCESS)
-                ret = GetStringAlloc(&modesSz, &modes, buf, len, &begin);
+                ret = GetStringAlloc(ssh->ctx->heap, &modes, &modesSz,
+                        buf, len, &begin);
             if (ret == WS_SUCCESS) {
                 WLOG(WS_LOG_DEBUG, "  term = %s", term);
                 WLOG(WS_LOG_DEBUG, "  widthChar = %u", widthChar);

wolfssh/internal.h

@@ -1024,7 +1024,7 @@ WOLFSSH_LOCAL int GetMpint(word32* mpintSz, const byte** mpint,
         const byte* buf, word32 len, word32* idx);
 WOLFSSH_LOCAL int GetString(char* s, word32* sSz,
         const byte* buf, word32 len, word32* idx);
-WOLFSSH_LOCAL int GetStringAlloc(void* heap, char** s,
+WOLFSSH_LOCAL int GetStringAlloc(void* heap, char** s, word32* sSz,
         const byte* buf, word32 len, word32* idx);
 WOLFSSH_LOCAL int GetStringRef(word32* strSz, const byte **str,
         const byte* buf, word32 len, word32* idx);