diff options
| author | Eric Dumazet <edumazet@google.com> | 2025-03-12 08:22:49 +0000 |
|---|---|---|
| committer | Paolo Abeni <pabeni@redhat.com> | 2025-03-18 13:18:36 +0100 |
| commit | eb0dfc0ef195a04e519b15d73cf25d8c25ee8df7 (patch) | |
| tree | 48152b079fdd9b88da44c66019531b708507b943 /net/ipv4 | |
| parent | a2fb987c0ecf0498cc17056339cb11d128c46ab7 (diff) | |
| download | ath-eb0dfc0ef195a04e519b15d73cf25d8c25ee8df7.tar.gz | |
inet: frags: change inet_frag_kill() to defer refcount updates
In the following patch, we no longer assume inet_frag_kill()
callers own a reference.
Consuming two refcounts from inet_frag_kill() would lead in UAF.
Propagate the pointer to the refs that will be consumed later
by the final inet_frag_putn() call.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20250312082250.1803501-4-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Diffstat (limited to 'net/ipv4')
| -rw-r--r-- | net/ipv4/inet_fragment.c | 12 | ||||
| -rw-r--r-- | net/ipv4/ip_fragment.c | 30 |
2 files changed, 19 insertions, 23 deletions
diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c index efc4cbee04c27..5eb1860500138 100644 --- a/net/ipv4/inet_fragment.c +++ b/net/ipv4/inet_fragment.c @@ -225,10 +225,10 @@ void fqdir_exit(struct fqdir *fqdir) } EXPORT_SYMBOL(fqdir_exit); -void inet_frag_kill(struct inet_frag_queue *fq) +void inet_frag_kill(struct inet_frag_queue *fq, int *refs) { if (del_timer(&fq->timer)) - refcount_dec(&fq->refcnt); + (*refs)++; if (!(fq->flags & INET_FRAG_COMPLETE)) { struct fqdir *fqdir = fq->fqdir; @@ -243,7 +243,7 @@ void inet_frag_kill(struct inet_frag_queue *fq) if (!READ_ONCE(fqdir->dead)) { rhashtable_remove_fast(&fqdir->rhashtable, &fq->node, fqdir->f->rhash_params); - refcount_dec(&fq->refcnt); + (*refs)++; } else { fq->flags |= INET_FRAG_HASH_DEAD; } @@ -349,9 +349,11 @@ static struct inet_frag_queue *inet_frag_create(struct fqdir *fqdir, *prev = rhashtable_lookup_get_insert_key(&fqdir->rhashtable, &q->key, &q->node, f->rhash_params); if (*prev) { + int refs = 2; + q->flags |= INET_FRAG_COMPLETE; - inet_frag_kill(q); - inet_frag_destroy(q); + inet_frag_kill(q, &refs); + inet_frag_putn(q, refs); return NULL; } return q; diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c index ee953be49b34d..c5f3c810706fb 100644 --- a/net/ipv4/ip_fragment.c +++ b/net/ipv4/ip_fragment.c @@ -76,7 +76,8 @@ static u8 ip4_frag_ecn(u8 tos) static struct inet_frags ip4_frags; static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb, - struct sk_buff *prev_tail, struct net_device *dev); + struct sk_buff *prev_tail, struct net_device *dev, + int *refs); static void ip4_frag_init(struct inet_frag_queue *q, const void *a) @@ -107,14 +108,6 @@ static void ip4_frag_free(struct inet_frag_queue *q) inet_putpeer(qp->peer); } -/* Kill ipq entry. It is not destroyed immediately, - * because caller (and someone more) holds reference count. - */ -static void ipq_kill(struct ipq *ipq) -{ - inet_frag_kill(&ipq->q); -} - static bool frag_expire_skip_icmp(u32 user) { return user == IP_DEFRAG_AF_PACKET || @@ -152,7 +145,7 @@ static void ip_expire(struct timer_list *t) goto out; qp->q.flags |= INET_FRAG_DROP; - ipq_kill(qp); + inet_frag_kill(&qp->q, &refs); __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); __IP_INC_STATS(net, IPSTATS_MIB_REASMTIMEOUT); @@ -271,7 +264,7 @@ static int ip_frag_reinit(struct ipq *qp) } /* Add new segment to existing queue. */ -static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) +static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb, int *refs) { struct net *net = qp->q.fqdir->net; int ihl, end, flags, offset; @@ -291,7 +284,7 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) if (!(IPCB(skb)->flags & IPSKB_FRAG_COMPLETE) && unlikely(ip_frag_too_far(qp)) && unlikely(err = ip_frag_reinit(qp))) { - ipq_kill(qp); + inet_frag_kill(&qp->q, refs); goto err; } @@ -375,10 +368,10 @@ static int ip_frag_queue(struct ipq *qp, struct sk_buff *skb) unsigned long orefdst = skb->_skb_refdst; skb->_skb_refdst = 0UL; - err = ip_frag_reasm(qp, skb, prev_tail, dev); + err = ip_frag_reasm(qp, skb, prev_tail, dev, refs); skb->_skb_refdst = orefdst; if (err) - inet_frag_kill(&qp->q); + inet_frag_kill(&qp->q, refs); return err; } @@ -395,7 +388,7 @@ insert_error: err = -EINVAL; __IP_INC_STATS(net, IPSTATS_MIB_REASM_OVERLAPS); discard_qp: - inet_frag_kill(&qp->q); + inet_frag_kill(&qp->q, refs); __IP_INC_STATS(net, IPSTATS_MIB_REASMFAILS); err: kfree_skb_reason(skb, reason); @@ -409,7 +402,8 @@ static bool ip_frag_coalesce_ok(const struct ipq *qp) /* Build a new IP datagram from all its fragments. */ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb, - struct sk_buff *prev_tail, struct net_device *dev) + struct sk_buff *prev_tail, struct net_device *dev, + int *refs) { struct net *net = qp->q.fqdir->net; struct iphdr *iph; @@ -417,7 +411,7 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *skb, int len, err; u8 ecn; - ipq_kill(qp); + inet_frag_kill(&qp->q, refs); ecn = ip_frag_ecn_table[qp->ecn]; if (unlikely(ecn == 0xff)) { @@ -495,7 +489,7 @@ int ip_defrag(struct net *net, struct sk_buff *skb, u32 user) spin_lock(&qp->q.lock); - ret = ip_frag_queue(qp, skb); + ret = ip_frag_queue(qp, skb, &refs); spin_unlock(&qp->q.lock); inet_frag_putn(&qp->q, refs); |