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net: ensure lookupStatic* returns copy of slice to disallow cache corruption.

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Fixes #14212

Change-Id: I74325dfaa1fb48f4b281c2d42157b563f1e42a94
Reviewed-on: https://go-review.googlesource.com/19201
Reviewed-by: Mikio Hara <mikioh.mikioh@gmail.com>
This commit is contained in:
Suharsh Sivakumar 2016-02-03 13:22:40 -08:00 committed by Mikio Hara
parent e43c74a0d8
commit 9ad41f6243
2 changed files with 54 additions and 16 deletions
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8
src/net/hosts.go
View File

@ -110,7 +110,9 @@ func lookupStaticHost(host string) []string {
lowerHost := []byte(host)
lowerASCIIBytes(lowerHost)
if ips, ok := hosts.byName[absDomainName(lowerHost)]; ok {
return ips
ipsCp := make([]string, len(ips))
copy(ipsCp, ips)
return ipsCp
}
}
return nil
@ -127,7 +129,9 @@ func lookupStaticAddr(addr string) []string {
}
if len(hosts.byAddr) != 0 {
if hosts, ok := hosts.byAddr[addr]; ok {
return hosts
hostsCp := make([]string, len(hosts))
copy(hostsCp, hosts)
return hostsCp
}
}
return nil

46
src/net/hosts_test.go
View File

@ -64,13 +64,17 @@ func TestLookupStaticHost(t *testing.T) {
for _, tt := range lookupStaticHostTests {
testHookHostsPath = tt.name
for _, ent := range tt.ents {
testStaticHost(t, tt.name, ent)
}
}
}
func testStaticHost(t *testing.T, hostsPath string, ent staticHostEntry) {
ins := []string{ent.in, absDomainName([]byte(ent.in)), strings.ToLower(ent.in), strings.ToUpper(ent.in)}
for _, in := range ins {
addrs := lookupStaticHost(in)
if !reflect.DeepEqual(addrs, ent.out) {
t.Errorf("%s, lookupStaticHost(%s) = %v; want %v", tt.name, in, addrs, ent.out)
}
}
t.Errorf("%s, lookupStaticHost(%s) = %v; want %v", hostsPath, in, addrs, ent.out)
}
}
}
@ -129,13 +133,43 @@ func TestLookupStaticAddr(t *testing.T) {
for _, tt := range lookupStaticAddrTests {
testHookHostsPath = tt.name
for _, ent := range tt.ents {
testStaticAddr(t, tt.name, ent)
}
}
}
func testStaticAddr(t *testing.T, hostsPath string, ent staticHostEntry) {
hosts := lookupStaticAddr(ent.in)
for i := range ent.out {
ent.out[i] = absDomainName([]byte(ent.out[i]))
}
if !reflect.DeepEqual(hosts, ent.out) {
t.Errorf("%s, lookupStaticAddr(%s) = %v; want %v", tt.name, ent.in, hosts, ent.out)
}
}
t.Errorf("%s, lookupStaticAddr(%s) = %v; want %v", hostsPath, ent.in, hosts, ent.out)
}
}
func TestHostCacheModification(t *testing.T) {
// Ensure that programs can't modify the internals of the host cache.
// See https://github.com/golang/go/issues/14212.
defer func(orig string) { testHookHostsPath = orig }(testHookHostsPath)
testHookHostsPath = "testdata/ipv4-hosts"
ent := staticHostEntry{"localhost", []string{"127.0.0.1", "127.0.0.2", "127.0.0.3"}}
testStaticHost(t, testHookHostsPath, ent)
// Modify the addresses return by lookupStaticHost.
addrs := lookupStaticHost(ent.in)
for i := range addrs {
addrs[i] += "junk"
}
testStaticHost(t, testHookHostsPath, ent)
testHookHostsPath = "testdata/ipv6-hosts"
ent = staticHostEntry{"::1", []string{"localhost"}}
testStaticAddr(t, testHookHostsPath, ent)
// Modify the hosts return by lookupStaticAddr.
hosts := lookupStaticAddr(ent.in)
for i := range hosts {
hosts[i] += "junk"
}
testStaticAddr(t, testHookHostsPath, ent)
}