Now sctp uses the transport without holding it in sctp_hash_cmp,
it can cause a use-after-free panic. As after it get transport from
hashtable, another CPU may free it, then the members it accesses
may be unavailable memory.
This patch is to use sctp_transport_hold, in which it checks the
refcnt first, holds it if it's not 0.
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
---
net/sctp/input.c | 27 +++++++++++++++++----------
1 file changed, 17 insertions(+), 10 deletions(-)
diff --git a/net/sctp/input.c b/net/sctp/input.c
index 69444d3..1555fb8 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -796,27 +796,34 @@ struct sctp_hash_cmp_arg {
static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg,
const void *ptr)
{
+ struct sctp_transport *t = (struct sctp_transport *)ptr;
const struct sctp_hash_cmp_arg *x = arg->key;
- const struct sctp_transport *t = ptr;
- struct sctp_association *asoc = t->asoc;
- const struct net *net = x->net;
+ struct sctp_association *asoc;
+ int err = 1;
if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr))
- return 1;
- if (!net_eq(sock_net(asoc->base.sk), net))
- return 1;
+ return err;
+ if (!sctp_transport_hold(t))
+ return err;
+
+ asoc = t->asoc;
+ if (!net_eq(sock_net(asoc->base.sk), x->net))
+ goto out;
if (x->ep) {
if (x->ep != asoc->ep)
- return 1;
+ goto out;
} else {
if (x->laddr->v4.sin_port != htons(asoc->base.bind_addr.port))
- return 1;
+ goto out;
if (!sctp_bind_addr_match(&asoc->base.bind_addr,
x->laddr, sctp_sk(asoc->base.sk)))
- return 1;
+ goto out;
}
- return 0;
+ err = 0;
+out:
+ sctp_transport_put(t);
+ return err;
}
static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed)
--
2.1.0
--
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