This is a note to let you know that I've just added the patch titled
packet: Move reference count in packet_sock to atomic_long_t
to the 4.19-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
packet-move-reference-count-in-packet_sock-to-atomic_long_t.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From db3fadacaf0c817b222090290d06ca2a338422d0 Mon Sep 17 00:00:00 2001
From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Date: Fri, 1 Dec 2023 14:10:21 +0100
Subject: packet: Move reference count in packet_sock to atomic_long_t
From: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
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@xxxxxxxxxxx>
Co-developed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: stable@xxxxxxxxxx
Reviewed-by: Willem de Bruijn <willemb@xxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20231201131021.19999-1-daniel@xxxxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
Patches currently in stable-queue which might be from daniel@xxxxxxxxxxxxx are
queue-4.19/packet-move-reference-count-in-packet_sock-to-atomic_long_t.patch
