From 17962e58c1130cd150b4a1475f4e8cad3ae67423 Mon Sep 17 00:00:00 2001
From: Konstantin Bogomolov <bogomolov@google.com>
Date: Fri, 10 Jan 2025 15:07:01 -0800
Subject: [PATCH] Replace unsafeSlice with unsafe.Slice.

reflect.SliceHeader has been deprecated.

PiperOrigin-RevId: 714222929
---
 nogo.yaml                                        |  1 +
 pkg/sentry/platform/ptrace/stub_unsafe.go        | 14 ++------------
 pkg/sentry/platform/systrap/stub_unsafe.go       | 16 +++-------------
 pkg/sentry/platform/systrap/subprocess_unsafe.go |  4 ++--
 4 files changed, 8 insertions(+), 27 deletions(-)

diff --git a/nogo.yaml b/nogo.yaml
index b6262ac06..8d4d4eeb5 100644
--- a/nogo.yaml
+++ b/nogo.yaml
@@ -198,6 +198,7 @@ analyzers:
         - pkg/sentry/platform/kvm/machine_unsafe.go                # Special case.
         - pkg/sentry/platform/kvm/bluepill_amd64_unsafe.go         # Special case.
         - pkg/sentry/platform/pgalloc/pgalloc_unsafe.go            # Special case.
+        - pkg/sentry/platform/ptrace/stub_unsafe.go                # Special case.
         - pkg/sentry/platform/systrap/stub_unsafe.go               # Special case.
         - pkg/sentry/platform/systrap/syscall_thread_unsafe.go     # Special case.
         - pkg/sentry/platform/systrap/sysmsg_thread_unsafe.go      # Special case.
diff --git a/pkg/sentry/platform/ptrace/stub_unsafe.go b/pkg/sentry/platform/ptrace/stub_unsafe.go
index 1fbdea898..39ad0e165 100644
--- a/pkg/sentry/platform/ptrace/stub_unsafe.go
+++ b/pkg/sentry/platform/ptrace/stub_unsafe.go
@@ -15,7 +15,6 @@
 package ptrace
 
 import (
-	"reflect"
 	"unsafe"
 
 	"golang.org/x/sys/unix"
@@ -36,21 +35,12 @@ func addrOfStub() uintptr
 // stubCall calls the stub at the given address with the given pid.
 func stubCall(addr, pid uintptr)
 
-// unsafeSlice returns a slice for the given address and length.
-func unsafeSlice(addr uintptr, length int) (slice []byte) {
-	sh := (*reflect.SliceHeader)(unsafe.Pointer(&slice))
-	sh.Data = addr
-	sh.Len = length
-	sh.Cap = length
-	return
-}
-
 // stubInit initializes the stub.
 func stubInit() {
 	// Grab the existing stub.
 	stubBegin := addrOfStub()
 	stubLen := int(safecopy.FindEndAddress(stubBegin) - stubBegin)
-	stubSlice := unsafeSlice(stubBegin, stubLen)
+	stubSlice := unsafe.Slice((*byte)(unsafe.Pointer(stubBegin)), stubLen)
 	mapLen := uintptr(stubLen)
 	if offset := mapLen % hostarch.PageSize; offset != 0 {
 		mapLen += hostarch.PageSize - offset
@@ -82,7 +72,7 @@ func stubInit() {
 		}
 
 		// Copy the stub to the address.
-		targetSlice := unsafeSlice(addr, stubLen)
+		targetSlice := unsafe.Slice((*byte)(unsafe.Pointer(addr)), stubLen)
 		copy(targetSlice, stubSlice)
 
 		// Make the stub executable.
diff --git a/pkg/sentry/platform/systrap/stub_unsafe.go b/pkg/sentry/platform/systrap/stub_unsafe.go
index 995bbe8aa..5c9f83b8b 100644
--- a/pkg/sentry/platform/systrap/stub_unsafe.go
+++ b/pkg/sentry/platform/systrap/stub_unsafe.go
@@ -46,15 +46,6 @@ func addrOfInitStubProcess() uintptr
 // stubCall calls the stub at the given address with the given pid.
 func stubCall(addr, pid uintptr)
 
-// unsafeSlice returns a slice for the given address and length.
-func unsafeSlice(addr uintptr, length int) (slice []byte) {
-	sh := (*reflect.SliceHeader)(unsafe.Pointer(&slice))
-	sh.Data = addr
-	sh.Len = length
-	sh.Cap = length
-	return
-}
-
 // prepareSeccompRules compiles stub process seccomp filters and fill
 // the sock_fprog structure. So the stub process will only need to call
 // seccomp system call to apply these filters.
@@ -199,7 +190,7 @@ func stubInit() {
 	// Grab the existing stub.
 	procStubBegin := addrOfInitStubProcess()
 	procStubLen := int(safecopy.FindEndAddress(procStubBegin) - procStubBegin)
-	procStubSlice := unsafeSlice(procStubBegin, procStubLen)
+	procStubSlice := unsafe.Slice((*byte)(unsafe.Pointer(procStubBegin)), procStubLen)
 	mapLen, _ := hostarch.PageRoundUp(uintptr(procStubLen))
 
 	stubSysmsgStart = mapLen
@@ -281,7 +272,7 @@ func stubInit() {
 	stubContextRegion += uintptr(gap)
 
 	// Copy the stub to the address.
-	targetSlice := unsafeSlice(stubStart, procStubLen)
+	targetSlice := unsafe.Slice((*byte)(unsafe.Pointer(stubStart)), procStubLen)
 	copy(targetSlice, procStubSlice)
 	stubInitProcess = stubStart
 
@@ -299,8 +290,7 @@ func stubInit() {
 	}
 	stubSysmsgRules += stubStart
 	stubSyscallRules += stubStart
-
-	targetSlice = unsafeSlice(stubSysmsgStart, stubSysmsgLen)
+	targetSlice = unsafe.Slice((*byte)(unsafe.Pointer(stubSysmsgStart)), stubSysmsgLen)
 	copy(targetSlice, sysmsg.SighandlerBlob)
 
 	// Initialize stub globals
diff --git a/pkg/sentry/platform/systrap/subprocess_unsafe.go b/pkg/sentry/platform/systrap/subprocess_unsafe.go
index c711865e7..38112c494 100644
--- a/pkg/sentry/platform/systrap/subprocess_unsafe.go
+++ b/pkg/sentry/platform/systrap/subprocess_unsafe.go
@@ -81,7 +81,7 @@ func mmapContextQueueForSentry(memoryFile *pgalloc.MemoryFile, opts pgalloc.Allo
 
 func saveFPState(ctx *sharedContext, ac *arch.Context64) {
 	fpState := ac.FloatingPointData().BytePointer()
-	dst := unsafeSlice(uintptr(unsafe.Pointer(fpState)), archState.FpLen())
+	dst := unsafe.Slice(fpState, archState.FpLen())
 	src := ctx.shared.FPState[:]
 	copy(dst, src)
 }
@@ -96,7 +96,7 @@ func restoreFPState(ctx *sharedContext, c *platformContext, ac *arch.Context64)
 	ctx.setFPStateChanged()
 
 	fpState := ac.FloatingPointData().BytePointer()
-	src := unsafeSlice(uintptr(unsafe.Pointer(fpState)), archState.FpLen())
+	src := unsafe.Slice(fpState, archState.FpLen())
 	dst := ctx.shared.FPState[:]
 	copy(dst, src)
 }