[PATCH] xfrm_user: return error pointer instead of NULL #2

From: Mathias Krause
Date: Fri Sep 14 2012 - 16:00:59 EST

When dump_one_policy() returns an error, e.g. because of a too small
buffer to dump the whole xfrm policy, xfrm_policy_netlink() returns
NULL instead of an error pointer. But its caller expects an error
pointer and therefore continues to operate on a NULL skbuff.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Mathias Krause <minipli@xxxxxxxxxxxxxx>

Note, this is a different, but similar issue as my previous patch
with the almost same subject.

I'm not aware of a way how to exploit this bug as the policy *should*
always fit into the netlink buffer but better safe then sorry, so cc

net/xfrm/xfrm_user.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index dac08e2..d12b625 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1548,6 +1548,7 @@ static struct sk_buff *xfrm_policy_netlink(struct sk_buff *in_skb,
struct xfrm_dump_info info;
struct sk_buff *skb;
+ int err;

if (!skb)
@@ -1558,9 +1559,10 @@ static struct sk_buff *xfrm_policy_netlink(struct sk_buff *in_skb,
info.nlmsg_seq = seq;
info.nlmsg_flags = 0;

- if (dump_one_policy(xp, dir, 0, &info) < 0) {
+ err = dump_one_policy(xp, dir, 0, &info);
+ if (err) {
- return NULL;
+ return ERR_PTR(err);

return skb;

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