[PATCH 17/17] net: convert packet_fanout.sk_ref from atomic_t to refcount_t
From: Elena Reshetova <elena.reshetova@intel.com>
Date: 2017-06-30 10:09:26
Also in:
bridge, lkml
Subsystem:
networking [general], packet sockets, the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Willem de Bruijn, Linus Torvalds
refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Hans Liljestrand <redacted> Signed-off-by: Kees Cook <redacted> Signed-off-by: David Windsor <redacted> --- net/packet/af_packet.c | 8 ++++---- net/packet/internal.h | 4 +++- 2 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 643302b..e3beb28 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c@@ -1739,7 +1739,7 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags) match->flags = flags; INIT_LIST_HEAD(&match->list); spin_lock_init(&match->lock); - atomic_set(&match->sk_ref, 0); + refcount_set(&match->sk_ref, 0); fanout_init_data(match); match->prot_hook.type = po->prot_hook.type; match->prot_hook.dev = po->prot_hook.dev;
@@ -1753,10 +1753,10 @@ static int fanout_add(struct sock *sk, u16 id, u16 type_flags) match->prot_hook.type == po->prot_hook.type && match->prot_hook.dev == po->prot_hook.dev) { err = -ENOSPC; - if (atomic_read(&match->sk_ref) < PACKET_FANOUT_MAX) { + if (refcount_read(&match->sk_ref) < PACKET_FANOUT_MAX) { __dev_remove_pack(&po->prot_hook); po->fanout = match; - atomic_inc(&match->sk_ref); + refcount_set(&match->sk_ref, refcount_read(&match->sk_ref) + 1); __fanout_link(sk, po); err = 0; }
@@ -1785,7 +1785,7 @@ static struct packet_fanout *fanout_release(struct sock *sk) if (f) { po->fanout = NULL; - if (atomic_dec_and_test(&f->sk_ref)) + if (refcount_dec_and_test(&f->sk_ref)) list_del(&f->list); else f = NULL;
diff --git a/net/packet/internal.h b/net/packet/internal.h
index 9ee4631..94d1d40 100644
--- a/net/packet/internal.h
+++ b/net/packet/internal.h@@ -1,6 +1,8 @@ #ifndef __PACKET_INTERNAL_H__ #define __PACKET_INTERNAL_H__ +#include <linux/refcount.h> + struct packet_mclist { struct packet_mclist *next; int ifindex;
@@ -86,7 +88,7 @@ struct packet_fanout { struct list_head list; struct sock *arr[PACKET_FANOUT_MAX]; spinlock_t lock; - atomic_t sk_ref; + refcount_t sk_ref; struct packet_type prot_hook ____cacheline_aligned_in_smp; };
--
2.7.4