[PATCH 09/36] net, atm: convert eg_cache_entry.use from atomic_t to refcount_t

From: Elena Reshetova
Date: Tue Jul 04 2017 - 08:55:28 EST


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@xxxxxxxxx>
Signed-off-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: David Windsor <dwindsor@xxxxxxxxx>
---
net/atm/mpoa_caches.c | 14 +++++++-------
net/atm/mpoa_caches.h | 2 +-
2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/net/atm/mpoa_caches.c b/net/atm/mpoa_caches.c
index 05e89e9..4ccaa16 100644
--- a/net/atm/mpoa_caches.c
+++ b/net/atm/mpoa_caches.c
@@ -339,7 +339,7 @@ static eg_cache_entry *eg_cache_get_by_cache_id(__be32 cache_id,
entry = mpc->eg_cache;
while (entry != NULL) {
if (entry->ctrl_info.cache_id == cache_id) {
- atomic_inc(&entry->use);
+ refcount_inc(&entry->use);
read_unlock_irq(&mpc->egress_lock);
return entry;
}
@@ -360,7 +360,7 @@ static eg_cache_entry *eg_cache_get_by_tag(__be32 tag, struct mpoa_client *mpc)
entry = mpc->eg_cache;
while (entry != NULL) {
if (entry->ctrl_info.tag == tag) {
- atomic_inc(&entry->use);
+ refcount_inc(&entry->use);
read_unlock_irqrestore(&mpc->egress_lock, flags);
return entry;
}
@@ -382,7 +382,7 @@ static eg_cache_entry *eg_cache_get_by_vcc(struct atm_vcc *vcc,
entry = mpc->eg_cache;
while (entry != NULL) {
if (entry->shortcut == vcc) {
- atomic_inc(&entry->use);
+ refcount_inc(&entry->use);
read_unlock_irqrestore(&mpc->egress_lock, flags);
return entry;
}
@@ -402,7 +402,7 @@ static eg_cache_entry *eg_cache_get_by_src_ip(__be32 ipaddr,
entry = mpc->eg_cache;
while (entry != NULL) {
if (entry->latest_ip_addr == ipaddr) {
- atomic_inc(&entry->use);
+ refcount_inc(&entry->use);
read_unlock_irq(&mpc->egress_lock);
return entry;
}
@@ -415,7 +415,7 @@ static eg_cache_entry *eg_cache_get_by_src_ip(__be32 ipaddr,

static void eg_cache_put(eg_cache_entry *entry)
{
- if (atomic_dec_and_test(&entry->use)) {
+ if (refcount_dec_and_test(&entry->use)) {
memset(entry, 0, sizeof(eg_cache_entry));
kfree(entry);
}
@@ -468,7 +468,7 @@ static eg_cache_entry *eg_cache_add_entry(struct k_message *msg,
dprintk("adding an egress entry, ip = %pI4, this should be our IP\n",
&msg->content.eg_info.eg_dst_ip);

- atomic_set(&entry->use, 1);
+ refcount_set(&entry->use, 1);
dprintk("new_eg_cache_entry: about to lock\n");
write_lock_irq(&client->egress_lock);
entry->next = client->eg_cache;
@@ -484,7 +484,7 @@ static eg_cache_entry *eg_cache_add_entry(struct k_message *msg,
dprintk("new_eg_cache_entry cache_id %u\n",
ntohl(entry->ctrl_info.cache_id));
dprintk("mps_ip = %pI4\n", &entry->ctrl_info.mps_ip);
- atomic_inc(&entry->use);
+ refcount_inc(&entry->use);

write_unlock_irq(&client->egress_lock);
dprintk("new_eg_cache_entry: unlocked\n");
diff --git a/net/atm/mpoa_caches.h b/net/atm/mpoa_caches.h
index 38a4e7e..30fe348 100644
--- a/net/atm/mpoa_caches.h
+++ b/net/atm/mpoa_caches.h
@@ -59,7 +59,7 @@ typedef struct eg_cache_entry{
uint16_t entry_state;
__be32 latest_ip_addr; /* The src IP address of the last packet */
struct eg_ctrl_info ctrl_info;
- atomic_t use;
+ refcount_t use;
} eg_cache_entry;

struct eg_cache_ops{
--
2.7.4