@@ -33,7 +33,7 @@ github.com/imdario/mergo                            1afb36080aec31e0d1528973ebe6

 golang.org/x/sync                                   cd5d95a43a6e21273425c7ae415d3df9ea832eeb

 # buildkit

-github.com/moby/buildkit                            81c2cbd8a418918d62b71e347a00034189eea455 # v0.8.3

+github.com/moby/buildkit                            244e8cde639f71a05a1a2e0670bd88e0206ce55c # v0.8.3-3-g244e8cde

 github.com/tonistiigi/fsutil                        0834f99b7b85462efb69b4f571a4fa3ca7da5ac9

 github.com/tonistiigi/units                         6950e57a87eaf136bbe44ef2ec8e75b9e3569de2

 github.com/grpc-ecosystem/grpc-opentracing          8e809c8a86450a29b90dcc9efbf062d0fe6d9746

@@ -3,6 +3,7 @@ package gateway

 import (

 	"context"

 	"fmt"

+	"path/filepath"

 	"runtime"

 	"sort"

 	"strings"

@@ -75,7 +76,7 @@ func NewContainer(ctx context.Context, w worker.Worker, sm *session.Manager, g s

 	name := fmt.Sprintf("container %s", req.ContainerID)

 	mm := mounts.NewMountManager(name, w.CacheManager(), sm, w.MetadataStore())

-	p, err := PrepareMounts(ctx, mm, w.CacheManager(), g, mnts, refs, func(m *opspb.Mount, ref cache.ImmutableRef) (cache.MutableRef, error) {

+	p, err := PrepareMounts(ctx, mm, w.CacheManager(), g, "", mnts, refs, func(m *opspb.Mount, ref cache.ImmutableRef) (cache.MutableRef, error) {

 		cm := w.CacheManager()

 		if m.Input != opspb.Empty {

 			cm = refs[m.Input].Worker.CacheManager()

@@ -132,7 +133,7 @@ type MountMutableRef struct {

 type MakeMutable func(m *opspb.Mount, ref cache.ImmutableRef) (cache.MutableRef, error)

-func PrepareMounts(ctx context.Context, mm *mounts.MountManager, cm cache.Manager, g session.Group, mnts []*opspb.Mount, refs []*worker.WorkerRef, makeMutable MakeMutable) (p PreparedMounts, err error) {

+func PrepareMounts(ctx context.Context, mm *mounts.MountManager, cm cache.Manager, g session.Group, cwd string, mnts []*opspb.Mount, refs []*worker.WorkerRef, makeMutable MakeMutable) (p PreparedMounts, err error) {

 	// loop over all mounts, fill in mounts, root and outputs

 	for i, m := range mnts {

 		var (

@@ -254,7 +255,11 @@ func PrepareMounts(ctx context.Context, mm *mounts.MountManager, cm cache.Manage

 			p.Root = mountWithSession(root, g)

 		} else {

 			mws := mountWithSession(mountable, g)

-			mws.Dest = m.Dest

+			dest := m.Dest

+			if !filepath.IsAbs(filepath.Clean(dest)) {

+				dest = filepath.Join("/", cwd, dest)

+			}

+			mws.Dest = dest

 			mws.Readonly = m.Readonly

 			mws.Selector = m.Selector

 			p.Mounts = append(p.Mounts, mws)

@@ -240,7 +240,7 @@ func (e *execOp) Exec(ctx context.Context, g session.Group, inputs []solver.Resu

 		}

 	}

-	p, err := gateway.PrepareMounts(ctx, e.mm, e.cm, g, e.op.Mounts, refs, func(m *pb.Mount, ref cache.ImmutableRef) (cache.MutableRef, error) {

+	p, err := gateway.PrepareMounts(ctx, e.mm, e.cm, g, e.op.Meta.Cwd, e.op.Mounts, refs, func(m *pb.Mount, ref cache.ImmutableRef) (cache.MutableRef, error) {

 		desc := fmt.Sprintf("mount %s from exec %s", m.Dest, strings.Join(e.op.Meta.Args, " "))

 		return e.cm.New(ctx, ref, g, cache.WithDescription(desc))

 	})