* [PATCH libnftnl 1/2] object: don't set NFTNL_OBJ_TYPE unless obj->ops is non-null
2017-02-27 14:56 [PATCH libnftnl 0/2] object: fix crashes with out-of-tree nft Florian Westphal
@ 2017-02-27 14:56 ` Florian Westphal
2017-02-27 15:59 ` Pablo Neira Ayuso
2017-02-27 14:56 ` [PATCH libnftnl 2/2] object: fix crash when object ops is null Florian Westphal
1 sibling, 1 reply; 5+ messages in thread
From: Florian Westphal @ 2017-02-27 14:56 UTC (permalink / raw)
To: netfilter-devel; +Cc: Florian Westphal
If nft sets an invalid type, nftnl_obj_ops_lookup will return NULL.
In this case we must not set NFTNL_OBJ_TYPE flag, else we later get
crash in nftnl_obj_nlmsg_build_payload as it dereferences obj->ops.
Signed-off-by: Florian Westphal <fw@strlen.de>
---
src/object.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/src/object.c b/src/object.c
index 9594d2f99071..62fa48afa2a1 100644
--- a/src/object.c
+++ b/src/object.c
@@ -83,6 +83,8 @@ void nftnl_obj_set_data(struct nftnl_obj *obj, uint16_t attr,
break;
case NFTNL_OBJ_TYPE:
obj->ops = nftnl_obj_ops_lookup(*((uint32_t *)data));
+ if (!obj->ops)
+ return;
break;
case NFTNL_OBJ_FAMILY:
obj->family = *((uint32_t *)data);
@@ -250,7 +252,8 @@ int nftnl_obj_nlmsg_parse(const struct nlmsghdr *nlh, struct nftnl_obj *obj)
uint32_t type = ntohl(mnl_attr_get_u32(tb[NFTA_OBJ_TYPE]));
obj->ops = nftnl_obj_ops_lookup(type);
- obj->flags |= (1 << NFTNL_OBJ_TYPE);
+ if (obj->ops)
+ obj->flags |= (1 << NFTNL_OBJ_TYPE);
}
if (tb[NFTA_OBJ_DATA]) {
if (obj->ops) {
--
2.10.2
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH libnftnl 2/2] object: fix crash when object ops is null
2017-02-27 14:56 [PATCH libnftnl 0/2] object: fix crashes with out-of-tree nft Florian Westphal
2017-02-27 14:56 ` [PATCH libnftnl 1/2] object: don't set NFTNL_OBJ_TYPE unless obj->ops is non-null Florian Westphal
@ 2017-02-27 14:56 ` Florian Westphal
2017-02-27 15:44 ` Pablo Neira Ayuso
1 sibling, 1 reply; 5+ messages in thread
From: Florian Westphal @ 2017-02-27 14:56 UTC (permalink / raw)
To: netfilter-devel; +Cc: Florian Westphal
when debugging nft with invalid object type (during development),
this will crash here with null deref. Print (unknown) instead
if obj->ops is null.
Signed-off-by: Florian Westphal <fw@strlen.de>
---
src/object.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/src/object.c b/src/object.c
index 62fa48afa2a1..773eff6a5a18 100644
--- a/src/object.c
+++ b/src/object.c
@@ -396,10 +396,11 @@ static int nftnl_obj_snprintf_dflt(char *buf, size_t size,
const struct nftnl_obj *obj,
uint32_t type, uint32_t flags)
{
+ const char *name = obj->ops ? obj->ops->name : "(unknown)";
int ret, len = size, offset = 0;
ret = snprintf(buf, size, "table %s name %s use %u [ %s ",
- obj->table, obj->name, obj->use, obj->ops->name);
+ obj->table, obj->name, obj->use, name);
SNPRINTF_BUFFER_SIZE(ret, size, len, offset);
if (obj->ops) {
--
2.10.2
^ permalink raw reply related [flat|nested] 5+ messages in thread