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net: convert packet_fanout.sk_ref from atomic_t to refcount_t

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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 <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Reshetova, Elena
2017-06-30 13:08:10 +03:00
committed by David S. Miller
parent b4217b8289
commit fb5c2c17a5
2 changed files with 7 additions and 5 deletions
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8
net/packet/af_packet.c
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@@ -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;