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Commit 9620fef2 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

ipv4: convert dst_metrics.refcnt from atomic_t to refcount_t 



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: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 633cefe3

include/net/dst.h

+2 −1
Original line number Original line Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/rcupdate.h>

#include <linux/rcupdate.h>

#include <linux/bug.h>

#include <linux/bug.h>

#include <linux/jiffies.h>

#include <linux/jiffies.h>

#include <linux/refcount.h>

#include <net/neighbour.h>

#include <net/neighbour.h>

#include <asm/processor.h>

#include <asm/processor.h>
@@ -107,7 +108,7 @@ struct dst_entry { 




struct dst_metrics {

struct dst_metrics {

	u32		metrics[RTAX_MAX];

	u32		metrics[RTAX_MAX];

	atomic_t	refcnt;

	refcount_t	refcnt;

};

};

extern const struct dst_metrics dst_default_metrics;

extern const struct dst_metrics dst_default_metrics;

net/core/dst.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -55,7 +55,7 @@ const struct dst_metrics dst_default_metrics = { 
	 * We really want to avoid false sharing on this variable, and catch

	 * We really want to avoid false sharing on this variable, and catch

	 * any writes on it.

	 * any writes on it.

	 */

	 */

	.refcnt = ATOMIC_INIT(1),

	.refcnt = REFCOUNT_INIT(1),

};

};





void dst_init(struct dst_entry *dst, struct dst_ops *ops,

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);

		struct dst_metrics *old_p = (struct dst_metrics *)__DST_METRICS_PTR(old);

		unsigned long prev, new;

		unsigned long prev, new;





		atomic_set(&p->refcnt, 1);

		refcount_set(&p->refcnt, 1);

		memcpy(p->metrics, old_p->metrics, sizeof(p->metrics));

		memcpy(p->metrics, old_p->metrics, sizeof(p->metrics));





		new = (unsigned long) p;

		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)

			if (prev & DST_METRICS_READ_ONLY)

				p = NULL;

				p = NULL;

		} else if (prev & DST_METRICS_REFCOUNTED) {

		} 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);

				kfree(old_p);

		}

		}

	}

	}

net/ipv4/fib_semantics.c

+2 −2
Original line number Original line Diff line number Diff line
@@ -220,7 +220,7 @@ static void free_fib_info_rcu(struct rcu_head *head) 
	} endfor_nexthops(fi);

	} endfor_nexthops(fi);





	m = fi->fib_metrics;

	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(m);

	kfree(fi);

	kfree(fi);

}

}
@@ -1090,7 +1090,7 @@ struct fib_info *fib_create_info(struct fib_config *cfg, 
			kfree(fi);

			kfree(fi);

			return ERR_PTR(err);

			return ERR_PTR(err);

		}

		}

		atomic_set(&fi->fib_metrics->refcnt, 1);

		refcount_set(&fi->fib_metrics->refcnt, 1);

	} else {

	} else {

		fi->fib_metrics = (struct dst_metrics *)&dst_default_metrics;

		fi->fib_metrics = (struct dst_metrics *)&dst_default_metrics;

	}

	}

net/ipv4/route.c

+2 −2
Original line number Original line Diff line number Diff line
@@ -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 dst_metrics *p = (struct dst_metrics *)DST_METRICS_PTR(dst);

	struct rtable *rt = (struct rtable *) 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);

		kfree(p);





	if (!list_empty(&rt->rt_uncached)) {

	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);

		dst_init_metrics(&rt->dst, fi->fib_metrics->metrics, true);

		if (fi->fib_metrics != &dst_default_metrics) {

		if (fi->fib_metrics != &dst_default_metrics) {

			rt->dst._metrics |= DST_METRICS_REFCOUNTED;

			rt->dst._metrics |= DST_METRICS_REFCOUNTED;

			atomic_inc(&fi->fib_metrics->refcnt);

			refcount_inc(&fi->fib_metrics->refcnt);

		}

		}

#ifdef CONFIG_IP_ROUTE_CLASSID

#ifdef CONFIG_IP_ROUTE_CLASSID

		rt->dst.tclassid = nh->nh_tclassid;

		rt->dst.tclassid = nh->nh_tclassid;