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cmd/5g, cmd/6g, cmd/8g: more nil ptr to large struct checks

Browse source 
R=r, ken, khr, daniel.morsing
CC=dsymonds, golang-dev, rickyz
https://golang.org/cl/8925043
This commit is contained in:
Ian Lance Taylor 2013-04-24 08:13:01 -07:00
parent 73417e4098
commit 578dc3a96c
4 changed files with 120 additions and 69 deletions
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17
src/cmd/5g/cgen.c
View file

@ -679,6 +679,19 @@ agen(Node *n, Node *res)
case ODOT:
agen(nl, res);
// explicit check for nil if struct is large enough
// that we might derive too big a pointer.
if(nl->type->width >= unmappedzero) {
regalloc(&n1, types[tptr], N);
gmove(res, &n1);
regalloc(&n2, types[TUINT8], &n1);
n1.op = OINDREG;
n1.type = types[TUINT8];
n1.xoffset = 0;
gmove(&n1, &n2);
regfree(&n1);
regfree(&n2);
}
if(n->xoffset != 0) {
nodconst(&n1, types[TINT32], n->xoffset);
regalloc(&n2, n1.type, N);
@ -694,7 +707,6 @@ agen(Node *n, Node *res)
case ODOTPTR:
cgen(nl, res);
if(n->xoffset != 0) {
// explicit check for nil if struct is large enough
// that we might derive too big a pointer.
if(nl->type->type->width >= unmappedzero) {
@ -708,6 +720,7 @@ agen(Node *n, Node *res)
regfree(&n1);
regfree(&n2);
}
if(n->xoffset != 0) {
nodconst(&n1, types[TINT32], n->xoffset);
regalloc(&n2, n1.type, N);
regalloc(&n3, types[tptr], N);
@ -777,7 +790,6 @@ igen(Node *n, Node *a, Node *res)
regalloc(a, types[tptr], res);
cgen(n->left, a);
}
if(n->xoffset != 0) {
// explicit check for nil if struct is large enough
// that we might derive too big a pointer.
if(n->left->type->type->width >= unmappedzero) {
@ -791,7 +803,6 @@ igen(Node *n, Node *a, Node *res)
regfree(&n1);
regfree(&n2);
}
}
a->op = OINDREG;
a->xoffset = n->xoffset;
a->type = n->type;

15
src/cmd/6g/cgen.c
View file

@ -882,13 +882,23 @@ agen(Node *n, Node *res)
case ODOT:
agen(nl, res);
// explicit check for nil if struct is large enough
// that we might derive too big a pointer.
if(nl->type->width >= unmappedzero) {
regalloc(&n1, types[tptr], res);
gmove(res, &n1);
n1.op = OINDREG;
n1.type = types[TUINT8];
n1.xoffset = 0;
gins(ATESTB, nodintconst(0), &n1);
regfree(&n1);
}
if(n->xoffset != 0)
ginscon(optoas(OADD, types[tptr]), n->xoffset, res);
break;
case ODOTPTR:
cgen(nl, res);
if(n->xoffset != 0) {
// explicit check for nil if struct is large enough
// that we might derive too big a pointer.
if(nl->type->type->width >= unmappedzero) {
@ -900,6 +910,7 @@ agen(Node *n, Node *res)
gins(ATESTB, nodintconst(0), &n1);
regfree(&n1);
}
if(n->xoffset != 0) {
ginscon(optoas(OADD, types[tptr]), n->xoffset, res);
}
break;
@ -950,7 +961,6 @@ igen(Node *n, Node *a, Node *res)
case ODOTPTR:
cgenr(n->left, a, res);
if(n->xoffset != 0) {
// explicit check for nil if struct is large enough
// that we might derive too big a pointer.
if(n->left->type->type->width >= unmappedzero) {
@ -960,7 +970,6 @@ igen(Node *n, Node *a, Node *res)
n1.xoffset = 0;
gins(ATESTB, nodintconst(0), &n1);
}
}
a->op = OINDREG;
a->xoffset += n->xoffset;
a->type = n->type;

15
src/cmd/8g/cgen.c
View file

@ -739,6 +739,17 @@ agen(Node *n, Node *res)
case ODOT:
agen(nl, res);
// explicit check for nil if struct is large enough
// that we might derive too big a pointer.
if(nl->type->width >= unmappedzero) {
regalloc(&n1, types[tptr], res);
gmove(res, &n1);
n1.op = OINDREG;
n1.type = types[TUINT8];
n1.xoffset = 0;
gins(ATESTB, nodintconst(0), &n1);
regfree(&n1);
}
if(n->xoffset != 0) {
nodconst(&n1, types[tptr], n->xoffset);
gins(optoas(OADD, types[tptr]), &n1, res);
@ -750,7 +761,6 @@ agen(Node *n, Node *res)
if(!isptr[t->etype])
fatal("agen: not ptr %N", n);
cgen(nl, res);
if(n->xoffset != 0) {
// explicit check for nil if struct is large enough
// that we might derive too big a pointer.
if(nl->type->type->width >= unmappedzero) {
@ -762,6 +772,7 @@ agen(Node *n, Node *res)
gins(ATESTB, nodintconst(0), &n1);
regfree(&n1);
}
if(n->xoffset != 0) {
nodconst(&n1, types[tptr], n->xoffset);
gins(optoas(OADD, types[tptr]), &n1, res);
}
@ -825,7 +836,6 @@ igen(Node *n, Node *a, Node *res)
regalloc(a, types[tptr], res);
cgen(n->left, a);
}
if(n->xoffset != 0) {
// explicit check for nil if struct is large enough
// that we might derive too big a pointer.
if(n->left->type->type->width >= unmappedzero) {
@ -835,7 +845,6 @@ igen(Node *n, Node *a, Node *res)
n1.xoffset = 0;
gins(ATESTB, nodintconst(0), &n1);
}
}
a->op = OINDREG;
a->xoffset += n->xoffset;
a->type = n->type;

22
test/nilptr.go
View file

@ -38,6 +38,8 @@ func main() {
shouldPanic(p8)
shouldPanic(p9)
shouldPanic(p10)
shouldPanic(p11)
shouldPanic(p12)
}
func shouldPanic(f func()) {
@ -130,3 +132,23 @@ func p10() {
var t *T
println(t.i) // should crash
}
type T1 struct {
T
}
type T2 struct {
*T1
}
func p11() {
t := &T2{}
p := &t.i
println(*p)
}
// ADDR(DOT(IND(p))) needs a check also
func p12() {
var p *T = nil
println(*(&((*p).i)))
}