[PATCH 23/36] net, rds: convert rds_message.m_refcount from atomic_t to refcount_t

From: Elena Reshetova
Date: Tue Jul 04 2017 - 08:57:29 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/rds/message.c | 12 ++++++------
net/rds/rds.h | 2 +-
2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/net/rds/message.c b/net/rds/message.c
index 49bfb51..4318cc9 100644
--- a/net/rds/message.c
+++ b/net/rds/message.c
@@ -48,8 +48,8 @@ static unsigned int rds_exthdr_size[__RDS_EXTHDR_MAX] = {

void rds_message_addref(struct rds_message *rm)
{
- rdsdebug("addref rm %p ref %d\n", rm, atomic_read(&rm->m_refcount));
- atomic_inc(&rm->m_refcount);
+ rdsdebug("addref rm %p ref %d\n", rm, refcount_read(&rm->m_refcount));
+ refcount_inc(&rm->m_refcount);
}
EXPORT_SYMBOL_GPL(rds_message_addref);

@@ -83,9 +83,9 @@ static void rds_message_purge(struct rds_message *rm)

void rds_message_put(struct rds_message *rm)
{
- rdsdebug("put rm %p ref %d\n", rm, atomic_read(&rm->m_refcount));
- WARN(!atomic_read(&rm->m_refcount), "danger refcount zero on %p\n", rm);
- if (atomic_dec_and_test(&rm->m_refcount)) {
+ rdsdebug("put rm %p ref %d\n", rm, refcount_read(&rm->m_refcount));
+ WARN(!refcount_read(&rm->m_refcount), "danger refcount zero on %p\n", rm);
+ if (refcount_dec_and_test(&rm->m_refcount)) {
BUG_ON(!list_empty(&rm->m_sock_item));
BUG_ON(!list_empty(&rm->m_conn_item));
rds_message_purge(rm);
@@ -206,7 +206,7 @@ struct rds_message *rds_message_alloc(unsigned int extra_len, gfp_t gfp)
rm->m_used_sgs = 0;
rm->m_total_sgs = extra_len / sizeof(struct scatterlist);

- atomic_set(&rm->m_refcount, 1);
+ refcount_set(&rm->m_refcount, 1);
INIT_LIST_HEAD(&rm->m_sock_item);
INIT_LIST_HEAD(&rm->m_conn_item);
spin_lock_init(&rm->m_rs_lock);
diff --git a/net/rds/rds.h b/net/rds/rds.h
index ea72d6e..516bcc8 100644
--- a/net/rds/rds.h
+++ b/net/rds/rds.h
@@ -356,7 +356,7 @@ static inline u32 rds_rdma_cookie_offset(rds_rdma_cookie_t cookie)
#define RDS_MSG_FLUSH 8

struct rds_message {
- atomic_t m_refcount;
+ refcount_t m_refcount;
struct list_head m_sock_item;
struct list_head m_conn_item;
struct rds_incoming m_inc;
--
2.7.4