Add bounds check to AddressTrackerLinux for struct ifa_cacheinfo

Bug: 1022111
Change-Id: Ie53859f448dff5fe60486738990e6bfd60cf5550
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1937783Reviewed-by: Paul Jensen <pauljensen@chromium.org>
Commit-Queue: Dan McArdle <dmcardle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#719633}

net/base/address_tracker_linux.cc

@@ -94,7 +94,12 @@ bool GetAddress(const struct nlmsghdr* header,
         local = reinterpret_cast<uint8_t*>(RTA_DATA(attr));
         break;
       case IFA_CACHEINFO: {
-        const struct ifa_cacheinfo *cache_info =
+        if (RTA_PAYLOAD(attr) < sizeof(struct ifa_cacheinfo)) {
+          LOG(ERROR)
+              << "attr does not have enough bytes to read an ifa_cacheinfo";
+          return false;
+        }
+        const struct ifa_cacheinfo* cache_info =
             reinterpret_cast<const struct ifa_cacheinfo*>(RTA_DATA(attr));
         if (really_deprecated)
           *really_deprecated = (cache_info->ifa_prefered == 0);