syscall: on exec failure, close pidfd

Fixes #69284

Change-Id: I6350209302778ba5e44fa03d0b9e680d2b4ec192
Reviewed-on: https://go-review.googlesource.com/c/go/+/611495
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: roger peppe <rogpeppe@gmail.com>
Reviewed-by: Tim King <taking@google.com>
Auto-Submit: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

6 files changed, 32 insertions, 0 deletions

diff --git a/src/syscall/exec_bsd.go b/src/syscall/exec_bsd.go
index 149cc2f11c..bbdab46de4 100644
--- a/src/syscall/exec_bsd.go
+++ b/src/syscall/exec_bsd.go
@@ -293,3 +293,8 @@ childerror:
 		RawSyscall(SYS_EXIT, 253, 0, 0)
 	}
 }
+
+// forkAndExecFailureCleanup cleans up after an exec failure.
+func forkAndExecFailureCleanup(attr *ProcAttr, sys *SysProcAttr) {
+	// Nothing to do.
+}
diff --git a/src/syscall/exec_freebsd.go b/src/syscall/exec_freebsd.go
index 3226cb88cd..686fd23bef 100644
--- a/src/syscall/exec_freebsd.go
+++ b/src/syscall/exec_freebsd.go
@@ -317,3 +317,8 @@ childerror:
 		RawSyscall(SYS_EXIT, 253, 0, 0)
 	}
 }
+
+// forkAndExecFailureCleanup cleans up after an exec failure.
+func forkAndExecFailureCleanup(attr *ProcAttr, sys *SysProcAttr) {
+	// Nothing to do.
+}
diff --git a/src/syscall/exec_libc.go b/src/syscall/exec_libc.go
index 768e8c131c..0e88650873 100644
--- a/src/syscall/exec_libc.go
+++ b/src/syscall/exec_libc.go
@@ -314,6 +314,11 @@ childerror:
 	}
 }
 
+// forkAndExecFailureCleanup cleans up after an exec failure.
+func forkAndExecFailureCleanup(attr *ProcAttr, sys *SysProcAttr) {
+	// Nothing to do.
+}
+
 func ioctlPtr(fd, req uintptr, arg unsafe.Pointer) (err Errno) {
 	return ioctl(fd, req, uintptr(arg))
 }
diff --git a/src/syscall/exec_libc2.go b/src/syscall/exec_libc2.go
index 7a67500844..a0579627a3 100644
--- a/src/syscall/exec_libc2.go
+++ b/src/syscall/exec_libc2.go
@@ -289,3 +289,8 @@ childerror:
 		rawSyscall(abi.FuncPCABI0(libc_exit_trampoline), 253, 0, 0)
 	}
 }
+
+// forkAndExecFailureCleanup cleans up after an exec failure.
+func forkAndExecFailureCleanup(attr *ProcAttr, sys *SysProcAttr) {
+	// Nothing to do.
+}
diff --git a/src/syscall/exec_linux.go b/src/syscall/exec_linux.go
index 415706c032..1859a58294 100644
--- a/src/syscall/exec_linux.go
+++ b/src/syscall/exec_linux.go
@@ -750,3 +750,11 @@ func writeUidGidMappings(pid int, sys *SysProcAttr) error {
 
 	return nil
 }
+
+// forkAndExecFailureCleanup cleans up after an exec failure.
+func forkAndExecFailureCleanup(attr *ProcAttr, sys *SysProcAttr) {
+	if sys.PidFD != nil && *sys.PidFD != -1 {
+		Close(*sys.PidFD)
+		*sys.PidFD = -1
+	}
+}
diff --git a/src/syscall/exec_unix.go b/src/syscall/exec_unix.go
index 1b90aa7e72..4747fa0758 100644
--- a/src/syscall/exec_unix.go
+++ b/src/syscall/exec_unix.go
@@ -237,6 +237,10 @@ func forkExec(argv0 string, argv []string, attr *ProcAttr) (pid int, err error)
 		for err1 == EINTR {
 			_, err1 = Wait4(pid, &wstatus, 0, nil)
 		}
+
+		// OS-specific cleanup on failure.
+		forkAndExecFailureCleanup(attr, sys)
+
 		return 0, err
 	}