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ipv4: convert dst_metrics.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: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2017-08-18 12:08:07 -07:00 committed by David S. Miller
parent 633cefe390
commit 9620fef27e
4 changed files with 9 additions and 8 deletions
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3
include/net/dst.h
View File

@ -14,6 +14,7 @@
#include <linux/rcupdate.h>
#include <linux/bug.h>
#include <linux/jiffies.h>
#include <linux/refcount.h>
#include <net/neighbour.h>
#include <asm/processor.h>
@ -107,7 +108,7 @@ struct dst_entry {
struct dst_metrics {
u32 metrics[RTAX_MAX];
atomic_t refcnt;
refcount_t refcnt;
};
extern const struct dst_metrics dst_default_metrics;

6
net/core/dst.c
View File

@ -55,7 +55,7 @@ const struct dst_metrics dst_default_metrics = {
* We really want to avoid false sharing on this variable, and catch
* any writes on it.
*/
.refcnt = ATOMIC_INIT(1),
.refcnt = REFCOUNT_INIT(1),
};
void dst_init(struct dst_entry *dst, struct dst_ops *ops,
@ -213,7 +213,7 @@ u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old)
struct dst_metrics *old_p = (struct dst_metrics *)__DST_METRICS_PTR(old);
unsigned long prev, new;
atomic_set(&p->refcnt, 1);
refcount_set(&p->refcnt, 1);
memcpy(p->metrics, old_p->metrics, sizeof(p->metrics));
new = (unsigned long) p;
@ -225,7 +225,7 @@ u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old)
if (prev & DST_METRICS_READ_ONLY)
p = NULL;
} else if (prev & DST_METRICS_REFCOUNTED) {
if (atomic_dec_and_test(&old_p->refcnt))
if (refcount_dec_and_test(&old_p->refcnt))
kfree(old_p);
}
}

4
net/ipv4/fib_semantics.c
View File

@ -220,7 +220,7 @@ static void free_fib_info_rcu(struct rcu_head *head)
} endfor_nexthops(fi);
m = fi->fib_metrics;
if (m != &dst_default_metrics && atomic_dec_and_test(&m->refcnt))
if (m != &dst_default_metrics && refcount_dec_and_test(&m->refcnt))
kfree(m);
kfree(fi);
}
@ -1090,7 +1090,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
kfree(fi);
return ERR_PTR(err);
}
atomic_set(&fi->fib_metrics->refcnt, 1);
refcount_set(&fi->fib_metrics->refcnt, 1);
} else {
fi->fib_metrics = (struct dst_metrics *)&dst_default_metrics;
}

4
net/ipv4/route.c
View File

@ -1398,7 +1398,7 @@ static void ipv4_dst_destroy(struct dst_entry *dst)
struct dst_metrics *p = (struct dst_metrics *)DST_METRICS_PTR(dst);
struct rtable *rt = (struct rtable *) dst;
if (p != &dst_default_metrics && atomic_dec_and_test(&p->refcnt))
if (p != &dst_default_metrics && refcount_dec_and_test(&p->refcnt))
kfree(p);
if (!list_empty(&rt->rt_uncached)) {
@ -1456,7 +1456,7 @@ static void rt_set_nexthop(struct rtable *rt, __be32 daddr,
dst_init_metrics(&rt->dst, fi->fib_metrics->metrics, true);
if (fi->fib_metrics != &dst_default_metrics) {
rt->dst._metrics |= DST_METRICS_REFCOUNTED;
atomic_inc(&fi->fib_metrics->refcnt);
refcount_inc(&fi->fib_metrics->refcnt);
}
#ifdef CONFIG_IP_ROUTE_CLASSID
rt->dst.tclassid = nh->nh_tclassid;