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From ac0d2377f612a16f1b452c7945e77dee93c0289e Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Thu, 30 Nov 2023 14:10:27 +0000
Subject: [PATCH] net/packet: move reference count in packet_sock to 64 bits
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 64bit atomic reference count to
prevent the possibility of this type of overflow.
Because we can not handle saturation, using refcount_t is not possible
in this place. Maybe someday in the future if it changes could it be
used.
Original version from Daniel after I did it wrong, I've provided a
changelog.
Reported-by: "The UK's National Cyber Security Centre (NCSC)" <security@ncsc.gov.uk>
Cc: stable <stable@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/packet/af_packet.c | 16 ++++++++--------
net/packet/internal.h | 2 +-
2 files changed, 9 insertions(+), 9 deletions(-)
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -4300,7 +4300,7 @@ static void packet_mm_open(struct vm_are
struct sock *sk = sock->sk;
if (sk)
- atomic_inc(&pkt_sk(sk)->mapped);
+ atomic64_inc(&pkt_sk(sk)->mapped);
}
static void packet_mm_close(struct vm_area_struct *vma)
@@ -4310,7 +4310,7 @@ static void packet_mm_close(struct vm_ar
struct sock *sk = sock->sk;
if (sk)
- atomic_dec(&pkt_sk(sk)->mapped);
+ atomic64_dec(&pkt_sk(sk)->mapped);
}
static const struct vm_operations_struct packet_mmap_ops = {
@@ -4405,7 +4405,7 @@ static int packet_set_ring(struct sock *
err = -EBUSY;
if (!closing) {
- if (atomic_read(&po->mapped))
+ if (atomic64_read(&po->mapped))
goto out;
if (packet_read_pending(rb))
goto out;
@@ -4508,7 +4508,7 @@ static int packet_set_ring(struct sock *
err = -EBUSY;
mutex_lock(&po->pg_vec_lock);
- if (closing || atomic_read(&po->mapped) == 0) {
+ if (closing || atomic64_read(&po->mapped) == 0) {
err = 0;
spin_lock_bh(&rb_queue->lock);
swap(rb->pg_vec, pg_vec);
@@ -4526,9 +4526,9 @@ static int packet_set_ring(struct sock *
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 (atomic64_read(&po->mapped))
+ pr_err("packet_mmap: vma is busy: %lld\n",
+ atomic64_read(&po->mapped));
}
mutex_unlock(&po->pg_vec_lock);
@@ -4606,7 +4606,7 @@ static int packet_mmap(struct file *file
}
}
- atomic_inc(&po->mapped);
+ atomic64_inc(&po->mapped);
vma->vm_ops = &packet_mmap_ops;
err = 0;
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -122,7 +122,7 @@ struct packet_sock {
__be16 num;
struct packet_rollover *rollover;
struct packet_mclist *mclist;
- atomic_t mapped;
+ atomic64_t mapped;
enum tpacket_versions tp_version;
unsigned int tp_hdrlen;
unsigned int tp_reserve;
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