Messages in this thread Patch in this message | | | From | Xiyu Yang <> | Subject | [PATCH] cxgb3: Convert from atomic_t to refcount_t on l2t_entry->refcnt | Date | Sat, 17 Jul 2021 18:16:15 +0800 |
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refcount_t type and corresponding API can protect refcounters from accidental underflow and overflow and further use-after-free situations.
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn> Signed-off-by: Xin Tan <tanxin.ctf@gmail.com> --- drivers/net/ethernet/chelsio/cxgb3/l2t.c | 15 ++++++++------- drivers/net/ethernet/chelsio/cxgb3/l2t.h | 10 +++++++--- 2 files changed, 15 insertions(+), 10 deletions(-)
diff --git a/drivers/net/ethernet/chelsio/cxgb3/l2t.c b/drivers/net/ethernet/chelsio/cxgb3/l2t.c index 9749d1239f58..0f2a47bc20d8 100644 --- a/drivers/net/ethernet/chelsio/cxgb3/l2t.c +++ b/drivers/net/ethernet/chelsio/cxgb3/l2t.c @@ -225,10 +225,11 @@ static struct l2t_entry *alloc_l2e(struct l2t_data *d) /* there's definitely a free entry */ for (e = d->rover, end = &d->l2tab[d->nentries]; e != end; ++e) - if (atomic_read(&e->refcnt) == 0) + if (refcount_read(&e->refcnt) == 0) goto found; - for (e = &d->l2tab[1]; atomic_read(&e->refcnt); ++e) ; + for (e = &d->l2tab[1]; refcount_read(&e->refcnt); ++e) + ; found: d->rover = e + 1; atomic_dec(&d->nfree); @@ -264,7 +265,7 @@ static struct l2t_entry *alloc_l2e(struct l2t_data *d) void t3_l2e_free(struct l2t_data *d, struct l2t_entry *e) { spin_lock_bh(&e->lock); - if (atomic_read(&e->refcnt) == 0) { /* hasn't been recycled */ + if (refcount_read(&e->refcnt) == 0) { /* hasn't been recycled */ if (e->neigh) { neigh_release(e->neigh); e->neigh = NULL; @@ -335,7 +336,7 @@ struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct dst_entry *dst, if (e->addr == addr && e->ifindex == ifidx && e->smt_idx == smt_idx) { l2t_hold(d, e); - if (atomic_read(&e->refcnt) == 1) + if (refcount_read(&e->refcnt) == 1) reuse_entry(e, neigh); goto done_unlock; } @@ -350,7 +351,7 @@ struct l2t_entry *t3_l2t_get(struct t3cdev *cdev, struct dst_entry *dst, e->addr = addr; e->ifindex = ifidx; e->smt_idx = smt_idx; - atomic_set(&e->refcnt, 1); + refcount_set(&e->refcnt, 1); neigh_replace(e, neigh); if (is_vlan_dev(neigh->dev)) e->vlan = vlan_dev_vlan_id(neigh->dev); @@ -418,7 +419,7 @@ void t3_l2t_update(struct t3cdev *dev, struct neighbour *neigh) __skb_queue_head_init(&arpq); read_unlock(&d->lock); - if (atomic_read(&e->refcnt)) { + if (refcount_read(&e->refcnt)) { if (neigh != e->neigh) neigh_replace(e, neigh); @@ -459,7 +460,7 @@ struct l2t_data *t3_init_l2t(unsigned int l2t_capacity) d->l2tab[i].state = L2T_STATE_UNUSED; __skb_queue_head_init(&d->l2tab[i].arpq); spin_lock_init(&d->l2tab[i].lock); - atomic_set(&d->l2tab[i].refcnt, 0); + refcount_set(&d->l2tab[i].refcnt, 0); } return d; } diff --git a/drivers/net/ethernet/chelsio/cxgb3/l2t.h b/drivers/net/ethernet/chelsio/cxgb3/l2t.h index ea75f275023f..bbdaa4a6aba2 100644 --- a/drivers/net/ethernet/chelsio/cxgb3/l2t.h +++ b/drivers/net/ethernet/chelsio/cxgb3/l2t.h @@ -35,6 +35,7 @@ #include <linux/spinlock.h> #include "t3cdev.h" #include <linux/atomic.h> +#include <linux/refcount.h> enum { L2T_STATE_VALID, /* entry is up to date */ @@ -66,7 +67,7 @@ struct l2t_entry { struct l2t_entry *next; /* next l2t_entry on chain */ struct sk_buff_head arpq; /* queue of packets awaiting resolution */ spinlock_t lock; - atomic_t refcnt; /* entry reference count */ + refcount_t refcnt; /* entry reference count */ u8 dmac[6]; /* neighbour's MAC address */ }; @@ -133,7 +134,7 @@ static inline void l2t_release(struct t3cdev *t, struct l2t_entry *e) rcu_read_lock(); d = L2DATA(t); - if (atomic_dec_and_test(&e->refcnt) && d) + if (refcount_dec_and_test(&e->refcnt) && d) t3_l2e_free(d, e); rcu_read_unlock(); @@ -141,7 +142,10 @@ static inline void l2t_release(struct t3cdev *t, struct l2t_entry *e) static inline void l2t_hold(struct l2t_data *d, struct l2t_entry *e) { - if (d && atomic_add_return(1, &e->refcnt) == 1) /* 0 -> 1 transition */ + if (!d) + return; + refcount_inc(&e->refcnt); + if (refcount_read(&e->refcnt) == 1) /* 0 -> 1 transition */ atomic_dec(&d->nfree); } -- 2.7.4
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