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net: convert (struct ubuf_info)->refcnt 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.

v2: added the change in drivers/vhost/net.c as spotted
by Willem.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2017-08-31 16:48:22 -07:00
committed by David S. Miller
parent db5bce32fb
commit c1d1b43781
3 changed files with 7 additions and 6 deletions
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6
net/core/skbuff.c
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@@ -963,7 +963,7 @@ struct ubuf_info *sock_zerocopy_alloc(struct sock *sk, size_t size)
uarg->len = 1;
uarg->bytelen = size;
uarg->zerocopy = 1;
atomic_set(&uarg->refcnt, 1);
refcount_set(&uarg->refcnt, 1);
sock_hold(sk);
return uarg;
@@ -1086,7 +1086,7 @@ EXPORT_SYMBOL_GPL(sock_zerocopy_callback);
void sock_zerocopy_put(struct ubuf_info *uarg)
{
if (uarg && atomic_dec_and_test(&uarg->refcnt)) {
if (uarg && refcount_dec_and_test(&uarg->refcnt)) {
if (uarg->callback)
uarg->callback(uarg, uarg->zerocopy);
else
@@ -1483,7 +1483,7 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
if (skb_orphan_frags(skb, gfp_mask))
goto nofrags;
if (skb_zcopy(skb))
atomic_inc(&skb_uarg(skb)->refcnt);
refcount_inc(&skb_uarg(skb)->refcnt);
for (i = 0; i < skb_shinfo(skb)->nr_frags; i++)
skb_frag_ref(skb, i);