linux: turn on -Wextra

sandbox/linux/seccomp/socketcall.cc

 // Copyright (c) 2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "debug.h"
 #include "sandbox_impl.h"
 
 namespace playground {
 
 #if defined(__NR_socket)
@@ skipping 270 matching lines @@
   // Read request
   struct {
     SendMsg sendmsg_req;
     struct msghdr   msg;
   } __attribute__((packed)) data;
   SysCalls sys;
   if (read(sys, sandboxFd, &data, sizeof(data)) != sizeof(data)) {
     die("Failed to read parameters for sendmsg() [process]");
   }
 
-  if (data.msg.msg_namelen    < 0 || data.msg.msg_namelen    > 4096 ||
-      data.msg.msg_controllen < 0 || data.msg.msg_controllen > 4096) {
+  if (data.msg.msg_namelen > 4096 || data.msg.msg_controllen > 4096) {
     die("Unexpected size for socketcall() payload [process]");
   }
   char extra[data.msg.msg_namelen + data.msg.msg_controllen];
   if (read(sys, sandboxFd, &extra, sizeof(extra)) != (ssize_t)sizeof(extra)) {
     die("Failed to read parameters for sendmsg() [process]");
   }
   if (sizeof(struct msghdr) + sizeof(extra) > sizeof(mem->pathname)) {
     goto deny;
   }
 
@@ skipping 457 matching lines @@
            sizeof(socklen_t));
   } else if (socketcall_req.call == SYS_SENDMSG) {
     numExtraData  = sizeof(*socketcall_req.args.sendmsg.msg);
   } else if (socketcall_req.call == SYS_RECVMSG) {
     numExtraData  = sizeof(*socketcall_req.args.recvmsg.msg);
   }
 
   // Verify that the length for the payload is reasonable. We don't want to
   // blow up our stack, and excessive (or negative) buffer sizes are almost
   // certainly a bug.
-  if (numExtraData < 0 || numExtraData > 4096) {
+  if (numExtraData > 4096) {
     die("Unexpected size for socketcall() payload [process]");
   }
 
   // Read the extra payload, if any.
   char extra[numExtraData];
   if (numExtraData) {
     if (read(sys, sandboxFd, extra, numExtraData) != (ssize_t)numExtraData) {
       die("Failed to read socketcall() payload [process]");
     }
   }
 
   // sendmsg() has another level of indirection and can carry even more payload
   ssize_t numSendmsgExtra = 0;
   if (socketcall_req.call == SYS_SENDMSG) {
     struct msghdr* msg = reinterpret_cast<struct msghdr*>(extra);
-    if (msg->msg_namelen    < 0 || msg->msg_namelen    > 4096 ||
-        msg->msg_controllen < 0 || msg->msg_controllen > 4096) {
+    if (msg->msg_namelen > 4096 || msg->msg_controllen > 4096) {
       die("Unexpected size for socketcall() payload [process]");
     }
     numSendmsgExtra = msg->msg_namelen + msg->msg_controllen;
   }
   char sendmsgExtra[numSendmsgExtra];
   if (numSendmsgExtra) {
     if (read(sys, sandboxFd, sendmsgExtra, numSendmsgExtra) !=
         numSendmsgExtra) {
       die("Failed to read socketcall() payload [process]");
     }
@@ skipping 234 matching lines @@
     default:
     deny:
       SecureMem::abandonSystemCall(threadFd, rc);
       return false;
   }
 }
 
 #endif
 
 } // namespace