From 148d8f0707fa9093156c6dad1ae10e7e2a9c9c1a Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Fri, 1 Dec 2023 14:10:21 +0100 Subject: packet: Move reference count in packet_sock to atomic_long_t commit db3fadacaf0c817b222090290d06ca2a338422d0 upstream. In some potential instances the reference count on struct packet_sock could be saturated and cause overflows which gets the kernel a bit confused. To prevent this, move to a 64-bit atomic reference count on 64-bit architectures to prevent the possibility of this type to overflow. Because we can not handle saturation, using refcount_t is not possible in this place. Maybe someday in the future if it changes it could be used. Also, instead of using plain atomic64_t, use atomic_long_t instead. 32-bit machines tend to be memory-limited (i.e. anything that increases a reference uses so much memory that you can't actually get to 2**32 references). 32-bit architectures also tend to have serious problems with 64-bit atomics. Hence, atomic_long_t is the more natural solution. Reported-by: "The UK's National Cyber Security Centre (NCSC)" Co-developed-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman Signed-off-by: Daniel Borkmann Cc: Linus Torvalds Cc: stable@kernel.org Reviewed-by: Willem de Bruijn Reviewed-by: Eric Dumazet Link: https://lore.kernel.org/r/20231201131021.19999-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/packet/af_packet.c | 16 ++++++++-------- net/packet/internal.h | 2 +- 2 files changed, 9 insertions(+), 9 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 0582abf5ab71..600a84a5c582 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -4240,7 +4240,7 @@ static void packet_mm_open(struct vm_area_struct *vma) struct sock *sk = sock->sk; if (sk) - atomic_inc(&pkt_sk(sk)->mapped); + atomic_long_inc(&pkt_sk(sk)->mapped); } static void packet_mm_close(struct vm_area_struct *vma) @@ -4250,7 +4250,7 @@ static void packet_mm_close(struct vm_area_struct *vma) struct sock *sk = sock->sk; if (sk) - atomic_dec(&pkt_sk(sk)->mapped); + atomic_long_dec(&pkt_sk(sk)->mapped); } static const struct vm_operations_struct packet_mmap_ops = { @@ -4345,7 +4345,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, err = -EBUSY; if (!closing) { - if (atomic_read(&po->mapped)) + if (atomic_long_read(&po->mapped)) goto out; if (packet_read_pending(rb)) goto out; @@ -4448,7 +4448,7 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, err = -EBUSY; mutex_lock(&po->pg_vec_lock); - if (closing || atomic_read(&po->mapped) == 0) { + if (closing || atomic_long_read(&po->mapped) == 0) { err = 0; spin_lock_bh(&rb_queue->lock); swap(rb->pg_vec, pg_vec); @@ -4466,9 +4466,9 @@ static int packet_set_ring(struct sock *sk, union tpacket_req_u *req_u, po->prot_hook.func = (po->rx_ring.pg_vec) ? tpacket_rcv : packet_rcv; skb_queue_purge(rb_queue); - if (atomic_read(&po->mapped)) - pr_err("packet_mmap: vma is busy: %d\n", - atomic_read(&po->mapped)); + if (atomic_long_read(&po->mapped)) + pr_err("packet_mmap: vma is busy: %ld\n", + atomic_long_read(&po->mapped)); } mutex_unlock(&po->pg_vec_lock); @@ -4546,7 +4546,7 @@ static int packet_mmap(struct file *file, struct socket *sock, } } - atomic_inc(&po->mapped); + atomic_long_inc(&po->mapped); vma->vm_ops = &packet_mmap_ops; err = 0; diff --git a/net/packet/internal.h b/net/packet/internal.h index 2b2b85dadf8e..878fcdca8c25 100644 --- a/net/packet/internal.h +++ b/net/packet/internal.h @@ -125,7 +125,7 @@ struct packet_sock { __be16 num; struct packet_rollover *rollover; struct packet_mclist *mclist; - atomic_t mapped; + atomic_long_t mapped; enum tpacket_versions tp_version; unsigned int tp_hdrlen; unsigned int tp_reserve; -- cgit v1.2.3