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net: convert fib_rule.refcnt from atomic_t to refcount_t

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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>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Reshetova, Elena 2017-06-30 13:08:06 +03:00 committed by David S. Miller
parent 8c9814b970
commit 717d1e993a
2 changed files with 6 additions and 5 deletions
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7
include/net/fib_rules.h
View File

@ -5,6 +5,7 @@
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/netdevice.h> #include <linux/netdevice.h>
#include <linux/fib_rules.h> #include <linux/fib_rules.h>
#include <linux/refcount.h>
#include <net/flow.h> #include <net/flow.h>
#include <net/rtnetlink.h> #include <net/rtnetlink.h>
@ -29,7 +30,7 @@ struct fib_rule {
struct fib_rule __rcu *ctarget; struct fib_rule __rcu *ctarget;
struct net *fr_net; struct net *fr_net;
atomic_t refcnt; refcount_t refcnt;
u32 pref; u32 pref;
int suppress_ifgroup; int suppress_ifgroup;
int suppress_prefixlen; int suppress_prefixlen;
@ -103,12 +104,12 @@ struct fib_rules_ops {
static inline void fib_rule_get(struct fib_rule *rule) static inline void fib_rule_get(struct fib_rule *rule)
{ {
atomic_inc(&rule->refcnt); refcount_inc(&rule->refcnt);
} }
static inline void fib_rule_put(struct fib_rule *rule) static inline void fib_rule_put(struct fib_rule *rule)
{ {
if (atomic_dec_and_test(&rule->refcnt)) if (refcount_dec_and_test(&rule->refcnt))
kfree_rcu(rule, rcu); kfree_rcu(rule, rcu);
} }

4
net/core/fib_rules.c
View File

@ -46,7 +46,7 @@ int fib_default_rule_add(struct fib_rules_ops *ops,
if (r == NULL) if (r == NULL)
return -ENOMEM; return -ENOMEM;
atomic_set(&r->refcnt, 1); refcount_set(&r->refcnt, 1);
r->action = FR_ACT_TO_TBL; r->action = FR_ACT_TO_TBL;
r->pref = pref; r->pref = pref;
r->table = table; r->table = table;
@ -283,7 +283,7 @@ jumped:
if (err != -EAGAIN) { if (err != -EAGAIN) {
if ((arg->flags & FIB_LOOKUP_NOREF) || if ((arg->flags & FIB_LOOKUP_NOREF) ||
likely(atomic_inc_not_zero(&rule->refcnt))) { likely(refcount_inc_not_zero(&rule->refcnt))) {
arg->rule = rule; arg->rule = rule;
goto out; goto out;
} }