4.19-stable review patch. If anyone has any objections, please let me know.
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From: Daniel Borkmann daniel@iogearbox.net
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)" security@ncsc.gov.uk Co-developed-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Daniel Borkmann daniel@iogearbox.net Cc: Linus Torvalds torvalds@linux-foundation.org Cc: stable@kernel.org Reviewed-by: Willem de Bruijn willemb@google.com Reviewed-by: Eric Dumazet edumazet@google.com Link: https://lore.kernel.org/r/20231201131021.19999-1-daniel@iogearbox.net Signed-off-by: Jakub Kicinski kuba@kernel.org 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 @@ -4214,7 +4214,7 @@ static void packet_mm_open(struct vm_are 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) @@ -4224,7 +4224,7 @@ static void packet_mm_close(struct vm_ar 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 = { @@ -4319,7 +4319,7 @@ static int packet_set_ring(struct sock *
err = -EBUSY; if (!closing) { - if (atomic_read(&po->mapped)) + if (atomic_long_read(&po->mapped)) goto out; if (packet_read_pending(rb)) goto out; @@ -4422,7 +4422,7 @@ static int packet_set_ring(struct sock *
err = -EBUSY; mutex_lock(&po->pg_vec_lock); - if (closing || atomic_read(&po->mapped) == 0) { + if (closing || atomic_long_read(&po->mapped) == 0) { err = 0; spin_lock_bh(&rb_queue->lock); swap(rb->pg_vec, pg_vec); @@ -4440,9 +4440,9 @@ 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 (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);
@@ -4520,7 +4520,7 @@ static int packet_mmap(struct file *file } }
- atomic_inc(&po->mapped); + atomic_long_inc(&po->mapped); vma->vm_ops = &packet_mmap_ops; err = 0;
--- 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;