[PATCH 05/36] net, decnet: convert dn_fib_info.fib_clntref from atomic_t to refcount_t

From: Elena Reshetova
Date: Tue Jul 04 2017 - 09:07:15 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>
---
include/net/dn_fib.h | 5 +++--
net/decnet/dn_fib.c | 6 +++---
2 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/include/net/dn_fib.h b/include/net/dn_fib.h
index f2ca135..81210a8 100644
--- a/include/net/dn_fib.h
+++ b/include/net/dn_fib.h
@@ -2,6 +2,7 @@
#define _NET_DN_FIB_H

#include <linux/netlink.h>
+#include <linux/refcount.h>

extern const struct nla_policy rtm_dn_policy[];

@@ -28,7 +29,7 @@ struct dn_fib_info {
struct dn_fib_info *fib_next;
struct dn_fib_info *fib_prev;
int fib_treeref;
- atomic_t fib_clntref;
+ refcount_t fib_clntref;
int fib_dead;
unsigned int fib_flags;
int fib_protocol;
@@ -130,7 +131,7 @@ void dn_fib_free_info(struct dn_fib_info *fi);

static inline void dn_fib_info_put(struct dn_fib_info *fi)
{
- if (atomic_dec_and_test(&fi->fib_clntref))
+ if (refcount_dec_and_test(&fi->fib_clntref))
dn_fib_free_info(fi);
}

diff --git a/net/decnet/dn_fib.c b/net/decnet/dn_fib.c
index f9058eb..f9f6fb3 100644
--- a/net/decnet/dn_fib.c
+++ b/net/decnet/dn_fib.c
@@ -389,7 +389,7 @@ struct dn_fib_info *dn_fib_create_info(const struct rtmsg *r, struct nlattr *att
}

fi->fib_treeref++;
- atomic_inc(&fi->fib_clntref);
+ refcount_set(&fi->fib_clntref, 1);
spin_lock(&dn_fib_info_lock);
fi->fib_next = dn_fib_info_list;
fi->fib_prev = NULL;
@@ -425,7 +425,7 @@ int dn_fib_semantic_match(int type, struct dn_fib_info *fi, const struct flowidn
switch (type) {
case RTN_NAT:
DN_FIB_RES_RESET(*res);
- atomic_inc(&fi->fib_clntref);
+ refcount_inc(&fi->fib_clntref);
return 0;
case RTN_UNICAST:
case RTN_LOCAL:
@@ -438,7 +438,7 @@ int dn_fib_semantic_match(int type, struct dn_fib_info *fi, const struct flowidn
}
if (nhsel < fi->fib_nhs) {
res->nh_sel = nhsel;
- atomic_inc(&fi->fib_clntref);
+ refcount_inc(&fi->fib_clntref);
return 0;
}
endfor_nexthops(fi);
--
2.7.4