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-rw-r--r--pkg/sentry/fsimpl/gofer/gofer.go4
-rw-r--r--pkg/sentry/fsimpl/gofer/regular_file.go9
2 files changed, 10 insertions, 3 deletions
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index d00850e25..c4a8f0b38 100644
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -1045,13 +1045,13 @@ func (d *dentry) ensureSharedHandle(ctx context.Context, read, write, trunc bool
// using the old file descriptor, preventing us from safely
// closing it. We could handle this by invalidating existing
// memmap.Translations, but this is expensive. Instead, use
- // dup2() to make the old file descriptor refer to the new file
+ // dup3 to make the old file descriptor refer to the new file
// description, then close the new file descriptor (which is no
// longer needed). Racing callers may use the old or new file
// description, but this doesn't matter since they refer to the
// same file (unless d.fs.opts.overlayfsStaleRead is true,
// which we handle separately).
- if err := syscall.Dup2(int(h.fd), int(d.handle.fd)); err != nil {
+ if err := syscall.Dup3(int(h.fd), int(d.handle.fd), 0); err != nil {
d.handleMu.Unlock()
ctx.Warningf("gofer.dentry.ensureSharedHandle: failed to dup fd %d to fd %d: %v", h.fd, d.handle.fd, err)
h.close(ctx)
diff --git a/pkg/sentry/fsimpl/gofer/regular_file.go b/pkg/sentry/fsimpl/gofer/regular_file.go
index 54c1031a7..e95209661 100644
--- a/pkg/sentry/fsimpl/gofer/regular_file.go
+++ b/pkg/sentry/fsimpl/gofer/regular_file.go
@@ -361,8 +361,15 @@ func (rw *dentryReadWriter) WriteFromBlocks(srcs safemem.BlockSeq) (uint64, erro
rw.d.handleMu.RLock()
if (rw.d.handle.fd >= 0 && !rw.d.fs.opts.forcePageCache) || rw.d.fs.opts.interop == InteropModeShared || rw.direct {
n, err := rw.d.handle.writeFromBlocksAt(rw.ctx, srcs, rw.off)
- rw.d.handleMu.RUnlock()
rw.off += n
+ rw.d.dataMu.Lock()
+ if rw.off > rw.d.size {
+ atomic.StoreUint64(&rw.d.size, rw.off)
+ // The remote file's size will implicitly be extended to the correct
+ // value when we write back to it.
+ }
+ rw.d.dataMu.Unlock()
+ rw.d.handleMu.RUnlock()
return n, err
}