[PATCH 6.1 21/71] netrom: Fix data-races around sysctl_netrom_network_ttl_initialiser

Sasha Levin
2024-03-13T16:40:24Z

From: Jason Xing <kernelxing@tencent.com>

[ Upstream commit 119cae5ea3f9e35cdada8e572cc067f072fa825a ]

We need to protect the reader reading the sysctl value because the
value can be changed concurrently.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Jason Xing <kernelxing@tencent.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/netrom/nr_dev.c | 2 +-
net/netrom/nr_out.c | 2 +-
net/netrom/nr_subr.c | 5 +++--
3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/net/netrom/nr_dev.c b/net/netrom/nr_dev.c
index 3aaac4a22b387..2c34389c3ce6f 100644
--- a/net/netrom/nr_dev.c
+++ b/net/netrom/nr_dev.c
@@ -81,7 +81,7 @@ static int nr_header(struct sk_buff *skb, struct net_device *dev,
buff[6] |= AX25_SSSID_SPARE;
buff += AX25_ADDR_LEN;

- *buff++ = sysctl_netrom_network_ttl_initialiser;
+ *buff++ = READ_ONCE(sysctl_netrom_network_ttl_initialiser);

*buff++ = NR_PROTO_IP;
*buff++ = NR_PROTO_IP;
diff --git a/net/netrom/nr_out.c b/net/netrom/nr_out.c
index 44929657f5b71..5e531394a724b 100644
--- a/net/netrom/nr_out.c
+++ b/net/netrom/nr_out.c
@@ -204,7 +204,7 @@ void nr_transmit_buffer(struct sock *sk, struct sk_buff *skb)
dptr[6] |= AX25_SSSID_SPARE;
dptr += AX25_ADDR_LEN;

- *dptr++ = sysctl_netrom_network_ttl_initialiser;
+ *dptr++ = READ_ONCE(sysctl_netrom_network_ttl_initialiser);

if (!nr_route_frame(skb, NULL)) {
kfree_skb(skb);
diff --git a/net/netrom/nr_subr.c b/net/netrom/nr_subr.c
index e2d2af924cff4..c3bbd5880850b 100644
--- a/net/netrom/nr_subr.c
+++ b/net/netrom/nr_subr.c
@@ -182,7 +182,8 @@ void nr_write_internal(struct sock *sk, int frametype)
*dptr++ = nr->my_id;
*dptr++ = frametype;
*dptr++ = nr->window;
- if (nr->bpqext) *dptr++ = sysctl_netrom_network_ttl_initialiser;
+ if (nr->bpqext)
+ *dptr++ = READ_ONCE(sysctl_netrom_network_ttl_initialiser);
break;

case NR_DISCREQ:
@@ -236,7 +237,7 @@ void __nr_transmit_reply(struct sk_buff *skb, int mine, unsigned char cmdflags)
dptr[6] |= AX25_SSSID_SPARE;
dptr += AX25_ADDR_LEN;

- *dptr++ = sysctl_netrom_network_ttl_initialiser;
+ *dptr++ = READ_ONCE(sysctl_netrom_network_ttl_initialiser);

if (mine) {
*dptr++ = 0;
--
2.43.0