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Commit b5a97e6f authored by Jeff Sharkey's avatar Jeff Sharkey
Browse files

Last-ditch clamping of negative NetworkStats. 

We've seen reports of negative values flowing through to attempt
being recorded, which will outright crash.  This change does one
last-ditch check to see if we're about to work with negative values,
reporting any trouble and clamping them to zero so we don't crash.

This gives us the data we need to continue investigating without
triggering runtime restarts in the field.

Bug: 80057433
Test: atest android.net.NetworkStatsTest
Change-Id: I8174391c6cf5dadc2c2c10a8d841ee07e1f7d934
parent b138eaa7

core/java/android/net/NetworkStats.java

+2 −0
Original line number Diff line number Diff line
@@ -1100,6 +1100,8 @@ public class NetworkStats implements Parcelable { 
    public interface NonMonotonicObserver<C> {

        public void foundNonMonotonic(

                NetworkStats left, int leftIndex, NetworkStats right, int rightIndex, C cookie);

        public void foundNonMonotonic(

                NetworkStats stats, int statsIndex, C cookie);

    }



    /**

services/core/java/com/android/server/net/NetworkStatsRecorder.java

+14 −0
Original line number Diff line number Diff line
@@ -241,6 +241,20 @@ public class NetworkStatsRecorder { 
        NetworkStats.Entry entry = null;

        for (int i = 0; i < delta.size(); i++) {

            entry = delta.getValues(i, entry);



            // As a last-ditch sanity check, report any negative values and

            // clamp them so recording below doesn't croak.

            if (entry.isNegative()) {

                if (mObserver != null) {

                    mObserver.foundNonMonotonic(delta, i, mCookie);

                }

                entry.rxBytes = Math.max(entry.rxBytes, 0);

                entry.rxPackets = Math.max(entry.rxPackets, 0);

                entry.txBytes = Math.max(entry.txBytes, 0);

                entry.txPackets = Math.max(entry.txPackets, 0);

                entry.operations = Math.max(entry.operations, 0);

            }



            final NetworkIdentitySet ident = ifaceIdent.get(entry.iface);

            if (ident == null) {

                unknownIfaces.add(entry.iface);

services/core/java/com/android/server/net/NetworkStatsService.java

+16 −4
Original line number Diff line number Diff line
@@ -1713,7 +1713,7 @@ public class NetworkStatsService extends INetworkStatsService.Stub { 
        @Override

        public void foundNonMonotonic(NetworkStats left, int leftIndex, NetworkStats right,

                int rightIndex, String cookie) {

            Log.w(TAG, "found non-monotonic values; saving to dropbox");

            Log.w(TAG, "Found non-monotonic values; saving to dropbox");



            // record error for debugging

            final StringBuilder builder = new StringBuilder();
@@ -1722,9 +1722,21 @@ public class NetworkStatsService extends INetworkStatsService.Stub { 
            builder.append("left=").append(left).append('\n');

            builder.append("right=").append(right).append('\n');



            final DropBoxManager dropBox = (DropBoxManager) mContext.getSystemService(

                    Context.DROPBOX_SERVICE);

            dropBox.addText(TAG_NETSTATS_ERROR, builder.toString());

            mContext.getSystemService(DropBoxManager.class).addText(TAG_NETSTATS_ERROR,

                    builder.toString());

        }



        @Override

        public void foundNonMonotonic(

                NetworkStats stats, int statsIndex, String cookie) {

            Log.w(TAG, "Found non-monotonic values; saving to dropbox");



            final StringBuilder builder = new StringBuilder();

            builder.append("Found non-monotonic " + cookie + " values at [" + statsIndex + "]\n");

            builder.append("stats=").append(stats).append('\n');



            mContext.getSystemService(DropBoxManager.class).addText(TAG_NETSTATS_ERROR,

                    builder.toString());

        }

    }