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Maintain the fuse buffer pool keyed by inode instead of threadId.

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In order to save memory, FuseAppLoop maintains a buffer pool to use
when dispatching the read/write requests. Currently, it uses
the threadId of the ProxyFileDescriptorCallback as the key for this
buffer pool and this can result in an issue when a caller creates
multiple ProxyFileDescriptors with ProxyFileDescriptorCallbacks
running on the same thread. When this happens, it is possible that
a buffer is reused before a read/write request which was using it
earlier has been handled and would result in data from read/write
requests on different fds getting mixed up.

Bug: 158568683
Test: atest --test-mapping apex/blobstore
Change-Id: Iaffd54f4430ecb3778f01c80f5a1684ac448f8dc
This commit is contained in:
Sudheer Shanka
2020-06-16 13:07:42 -07:00
parent 38da493ae4
commit c608143486
1 changed files with 9 additions and 9 deletions
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18
core/java/com/android/internal/os/FuseAppLoop.java
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@@ -210,7 +210,7 @@ public class FuseAppLoop implements Handler.Callback {
if (mInstance != 0) {
native_replySimple(mInstance, unique, FUSE_OK);
}
mBytesMap.stopUsing(entry.getThreadId());
mBytesMap.stopUsing(inode);
recycleLocked(args);
}
break;
@@ -270,7 +270,7 @@ public class FuseAppLoop implements Handler.Callback {
if (mInstance != 0) {
native_replyOpen(mInstance, unique, /* fh */ inode);
entry.opened = true;
return mBytesMap.startUsing(entry.getThreadId());
return mBytesMap.startUsing(inode);
}
} catch (ErrnoException error) {
replySimpleLocked(unique, getError(error));
@@ -354,27 +354,27 @@ public class FuseAppLoop implements Handler.Callback {
}
/**
* Map between Thread ID and byte buffer.
* Map between inode and byte buffer.
*/
private static class BytesMap {
final Map<Long, BytesMapEntry> mEntries = new HashMap<>();
byte[] startUsing(long threadId) {
BytesMapEntry entry = mEntries.get(threadId);
byte[] startUsing(long inode) {
BytesMapEntry entry = mEntries.get(inode);
if (entry == null) {
entry = new BytesMapEntry();
mEntries.put(threadId, entry);
mEntries.put(inode, entry);
}
entry.counter++;
return entry.bytes;
}
void stopUsing(long threadId) {
final BytesMapEntry entry = mEntries.get(threadId);
void stopUsing(long inode) {
final BytesMapEntry entry = mEntries.get(inode);
Objects.requireNonNull(entry);
entry.counter--;
if (entry.counter <= 0) {
mEntries.remove(threadId);
mEntries.remove(inode);
}
}