Fix misuses of kernel.Task as context.Context.

kernel.Task can only be used as context.Context by that Task's task goroutine.
This is violated in at least two places:

- In any case where one thread accesses the /proc/[tid] of any other thread,
  passing the kernel.Task for [tid] as the context.Context is incorrect.

- Task.rebuildTraceContext() may be called by Kernel.RebuildTraceContexts()
  outside the scope of any task goroutine.

Fix these (as well as a data race on Task.traceContext discovered during the
course of finding the latter).

PiperOrigin-RevId: 342174404

1 files changed, 2 insertions, 1 deletions

diff --git a/pkg/sentry/kernel/task_log.go b/pkg/sentry/kernel/task_log.go
index 7591eaace..c70e5e6ce 100644
--- a/pkg/sentry/kernel/task_log.go
+++ b/pkg/sentry/kernel/task_log.go
@@ -19,6 +19,7 @@ import (
 	"runtime/trace"
 	"sort"
 
+	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/usermem"
 )
@@ -215,7 +216,7 @@ func (t *Task) rebuildTraceContext(tid ThreadID) {
 	// arbitrarily large (in general it won't be, especially for cases
 	// where we're collecting a brief profile), so using the TID is a
 	// reasonable compromise in this case.
-	t.traceContext, t.traceTask = trace.NewTask(t, fmt.Sprintf("tid:%d", tid))
+	t.traceContext, t.traceTask = trace.NewTask(context.Background(), fmt.Sprintf("tid:%d", tid))
 }
 
 // traceCloneEvent is called when a new task is spawned.