Internal change.

PiperOrigin-RevId: 381375705

2 files changed, 18 insertions, 8 deletions

diff --git a/pkg/sentry/hostfd/hostfd_linux.go b/pkg/sentry/hostfd/hostfd_linux.go
index 1cabc848f..e103e7296 100644
--- a/pkg/sentry/hostfd/hostfd_linux.go
+++ b/pkg/sentry/hostfd/hostfd_linux.go
@@ -14,5 +14,10 @@
 
 package hostfd
 
-// maxIov is the maximum permitted size of a struct iovec array.
-const maxIov = 1024 // UIO_MAXIOV
+// MaxReadWriteIov is the maximum permitted size of a struct iovec array in a
+// readv, writev, preadv, or pwritev host syscall.
+const MaxReadWriteIov = 1024 // UIO_MAXIOV
+
+// MaxSendRecvMsgIov is the maximum permitted size of a struct iovec array in a
+// sendmsg or recvmsg host syscall.
+const MaxSendRecvMsgIov = 1024 // UIO_MAXIOV
diff --git a/pkg/sentry/hostfd/hostfd_unsafe.go b/pkg/sentry/hostfd/hostfd_unsafe.go
index 03c6d2a16..a43311eb4 100644
--- a/pkg/sentry/hostfd/hostfd_unsafe.go
+++ b/pkg/sentry/hostfd/hostfd_unsafe.go
@@ -23,6 +23,11 @@ import (
 	"gvisor.dev/gvisor/pkg/safemem"
 )
 
+const (
+	sizeofIovec  = unsafe.Sizeof(unix.Iovec{})
+	sizeofMsghdr = unsafe.Sizeof(unix.Msghdr{})
+)
+
 // Preadv2 reads up to dsts.NumBytes() bytes from host file descriptor fd into
 // dsts. offset and flags are interpreted as for preadv2(2).
 //
@@ -44,9 +49,9 @@ func Preadv2(fd int32, dsts safemem.BlockSeq, offset int64, flags uint32) (uint6
 		}
 	} else {
 		iovs := safemem.IovecsFromBlockSeq(dsts)
-		if len(iovs) > maxIov {
-			log.Debugf("hostfd.Preadv2: truncating from %d iovecs to %d", len(iovs), maxIov)
-			iovs = iovs[:maxIov]
+		if len(iovs) > MaxReadWriteIov {
+			log.Debugf("hostfd.Preadv2: truncating from %d iovecs to %d", len(iovs), MaxReadWriteIov)
+			iovs = iovs[:MaxReadWriteIov]
 		}
 		n, _, e = unix.Syscall6(unix.SYS_PREADV2, uintptr(fd), uintptr((unsafe.Pointer)(&iovs[0])), uintptr(len(iovs)), uintptr(offset), 0 /* pos_h */, uintptr(flags))
 	}
@@ -80,9 +85,9 @@ func Pwritev2(fd int32, srcs safemem.BlockSeq, offset int64, flags uint32) (uint
 		}
 	} else {
 		iovs := safemem.IovecsFromBlockSeq(srcs)
-		if len(iovs) > maxIov {
-			log.Debugf("hostfd.Preadv2: truncating from %d iovecs to %d", len(iovs), maxIov)
-			iovs = iovs[:maxIov]
+		if len(iovs) > MaxReadWriteIov {
+			log.Debugf("hostfd.Preadv2: truncating from %d iovecs to %d", len(iovs), MaxReadWriteIov)
+			iovs = iovs[:MaxReadWriteIov]
 		}
 		n, _, e = unix.Syscall6(unix.SYS_PWRITEV2, uintptr(fd), uintptr((unsafe.Pointer)(&iovs[0])), uintptr(len(iovs)), uintptr(offset), 0 /* pos_h */, uintptr(flags))
 	}