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authorKevin Krakauer <krakauer@google.com>2018-08-14 15:48:52 -0700
committerShentubot <shentubot@google.com>2018-08-14 15:49:58 -0700
commit12a4912aedc834fc8f404dc1ffeaa37088dd2d6b (patch)
treeec25ead4cbfe3476e53e793ff01021b6074361c8
parente97717e29a1bb3e373b130086c4182c598a8121c (diff)
Fix `ls -laR | wc -l` hanging.
stat()-ing /proc/PID/fd/FD incremented but didn't decrement the refcount for FD. This behavior wasn't usually noticeable, but in the above case: - ls would never decrement the refcount of the write end of the pipe to 0. - This caused the write end of the pipe never to close. - wc would then hang read()-ing from the pipe. PiperOrigin-RevId: 208728817 Change-Id: I4fca1ba5ca24e4108915a1d30b41dc63da40604d
-rw-r--r--pkg/sentry/fs/proc/fds.go15
1 files changed, 13 insertions, 2 deletions
diff --git a/pkg/sentry/fs/proc/fds.go b/pkg/sentry/fs/proc/fds.go
index cca8f874c..dada8f982 100644
--- a/pkg/sentry/fs/proc/fds.go
+++ b/pkg/sentry/fs/proc/fds.go
@@ -94,7 +94,7 @@ type fd struct {
*fs.File
}
-// newFD returns a new fd based on an existing file.
+// newFd returns a new fd based on an existing file.
//
// This inherits one reference to the file.
func newFd(t *kernel.Task, f *fs.File, msrc *fs.MountSource) *fs.Inode {
@@ -131,6 +131,11 @@ func (f *fd) Truncate(context.Context, *fs.Inode, int64) error {
return nil
}
+func (f *fd) Release(ctx context.Context) {
+ f.Symlink.Release(ctx)
+ f.File.DecRef()
+}
+
// Close releases the reference on the file.
func (f *fd) Close() error {
f.DecRef()
@@ -204,13 +209,14 @@ func (f *fdDir) DeprecatedReaddir(ctx context.Context, dirCtx *fs.DirCtx, offset
type fdInfo struct {
ramfs.File
+ file *fs.File
flags fs.FileFlags
fdFlags kernel.FDFlags
}
// newFdInfo returns a new fdInfo based on an existing file.
func newFdInfo(t *kernel.Task, file *fs.File, fdFlags kernel.FDFlags, msrc *fs.MountSource) *fs.Inode {
- fdi := &fdInfo{flags: file.Flags(), fdFlags: fdFlags}
+ fdi := &fdInfo{file: file, flags: file.Flags(), fdFlags: fdFlags}
fdi.InitFile(t, fs.RootOwner, fs.FilePermissions{User: fs.PermMask{Read: true}})
// TODO: Get pos, locks, and other data. For now we only
// have flags.
@@ -231,6 +237,11 @@ func (*fdInfo) Truncate(ctx context.Context, inode *fs.Inode, size int64) error
return ramfs.ErrInvalidOp
}
+func (f *fdInfo) Release(ctx context.Context) {
+ f.File.Release(ctx)
+ f.file.DecRef()
+}
+
// fdInfoDir implements /proc/TID/fdinfo. It embeds an fdDir, but overrides
// Lookup and Readdir.
//