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Subject[PATCH 12/17] net: convert unix_address.refcnt from atomic_t to refcount_t
Date
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>
---
include/net/af_unix.h | 3 ++-
net/unix/af_unix.c | 8 ++++----
2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index fd60ecc..3a385e4 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -4,6 +4,7 @@
#include <linux/socket.h>
#include <linux/un.h>
#include <linux/mutex.h>
+#include <linux/refcount.h>
#include <net/sock.h>

void unix_inflight(struct user_struct *user, struct file *fp);
@@ -21,7 +22,7 @@ extern spinlock_t unix_table_lock;
extern struct hlist_head unix_socket_table[2 * UNIX_HASH_SIZE];

struct unix_address {
- atomic_t refcnt;
+ refcount_t refcnt;
int len;
unsigned int hash;
struct sockaddr_un name[0];
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index c885254..b9ee766 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -212,7 +212,7 @@ EXPORT_SYMBOL_GPL(unix_peer_get);

static inline void unix_release_addr(struct unix_address *addr)
{
- if (atomic_dec_and_test(&addr->refcnt))
+ if (refcount_dec_and_test(&addr->refcnt))
kfree(addr);
}

@@ -864,7 +864,7 @@ static int unix_autobind(struct socket *sock)
goto out;

addr->name->sun_family = AF_UNIX;
- atomic_set(&addr->refcnt, 1);
+ refcount_set(&addr->refcnt, 1);

retry:
addr->len = sprintf(addr->name->sun_path+1, "%05x", ordernum) + 1 + sizeof(short);
@@ -1040,7 +1040,7 @@ static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
memcpy(addr->name, sunaddr, addr_len);
addr->len = addr_len;
addr->hash = hash ^ sk->sk_type;
- atomic_set(&addr->refcnt, 1);
+ refcount_set(&addr->refcnt, 1);

if (sun_path[0]) {
addr->hash = UNIX_HASH_SIZE;
@@ -1335,7 +1335,7 @@ static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,

/* copy address information from listening to new sock*/
if (otheru->addr) {
- atomic_inc(&otheru->addr->refcnt);
+ refcount_inc(&otheru->addr->refcnt);
newu->addr = otheru->addr;
}
if (otheru->path.dentry) {
--
2.7.4
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