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qeth: convert qeth_reply.refcnt from atomic_t to refcount_t
atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable qeth_reply.refcnt is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> [jwi: removed the WARN_ONs. Use CONFIG_REFCOUNT_FULL if you care.] Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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2 changed files with 5 additions and 6 deletions
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@ -21,6 +21,7 @@
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#include <linux/ethtool.h>
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#include <linux/hashtable.h>
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#include <linux/ip.h>
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#include <linux/refcount.h>
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#include <net/ipv6.h>
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#include <net/if_inet6.h>
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@ -632,7 +633,7 @@ struct qeth_reply {
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int rc;
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void *param;
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struct qeth_card *card;
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atomic_t refcnt;
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refcount_t refcnt;
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};
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struct qeth_card_blkt {
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@ -564,7 +564,7 @@ static struct qeth_reply *qeth_alloc_reply(struct qeth_card *card)
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reply = kzalloc(sizeof(struct qeth_reply), GFP_ATOMIC);
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if (reply) {
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atomic_set(&reply->refcnt, 1);
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refcount_set(&reply->refcnt, 1);
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atomic_set(&reply->received, 0);
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reply->card = card;
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}
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@ -573,14 +573,12 @@ static struct qeth_reply *qeth_alloc_reply(struct qeth_card *card)
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static void qeth_get_reply(struct qeth_reply *reply)
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{
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WARN_ON(atomic_read(&reply->refcnt) <= 0);
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atomic_inc(&reply->refcnt);
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refcount_inc(&reply->refcnt);
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}
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static void qeth_put_reply(struct qeth_reply *reply)
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{
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WARN_ON(atomic_read(&reply->refcnt) <= 0);
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if (atomic_dec_and_test(&reply->refcnt))
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if (refcount_dec_and_test(&reply->refcnt))
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kfree(reply);
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}
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