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[PATCH net-next v6 8/8] ax.25: x.25: Remove the now superfluous sentinel

To: "David S. Miller" <davem@xxxxxxxxxxxxx>, Eric Dumazet <edumazet@xxxxxxxxxx>, Jakub Kicinski <kuba@xxxxxxxxxx>, Paolo Abeni <pabeni@xxxxxxxxxx>, Alexander Aring <alex.aring@xxxxxxxxx>, Stefan Schmidt <stefan@xxxxxxxxxxxxxxxxxx>, Miquel Raynal <miquel.raynal@xxxxxxxxxxx>, David Ahern <dsahern@xxxxxxxxxx>, Steffen Klassert <steffen.klassert@xxxxxxxxxxx>, Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>, Matthieu Baerts <matttbe@xxxxxxxxxx>, Mat Martineau <martineau@xxxxxxxxxx>, Geliang Tang <geliang@xxxxxxxxxx>, Ralf Baechle <ralf@xxxxxxxxxxxxxx>, Remi Denis-Courmont <courmisch@xxxxxxxxx>, Allison Henderson <allison.henderson@xxxxxxxxxx>, David Howells <dhowells@xxxxxxxxxx>, Marc Dionne <marc.dionne@xxxxxxxxxxxx>, Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>, Xin Long <lucien.xin@xxxxxxxxx>, Wenjia Zhang <wenjia@xxxxxxxxxxxxx>, Jan Karcher <jaka@xxxxxxxxxxxxx>, "D. Wythe" <alibuda@xxxxxxxxxxxxxxxxx>, Tony Lu <tonylu@xxxxxxxxxxxxxxxxx>, Wen Gu <guwen@xxxxxxxxxxxxxxxxx>, Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>, Anna Schumaker <anna@xxxxxxxxxx>, Chuck Lever <chuck.lever@xxxxxxxxxx>, Jeff Layton <jlayton@xxxxxxxxxx>, Neil Brown <neilb@xxxxxxx>, Olga Kornievskaia <kolga@xxxxxxxxxx>, Dai Ngo <Dai.Ngo@xxxxxxxxxx>, Tom Talpey <tom@xxxxxxxxxx>, Jon Maloy <jmaloy@xxxxxxxxxx>, Ying Xue <ying.xue@xxxxxxxxxxxxx>, Martin Schiller <ms@xxxxxxxxxx>, Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>, Jozsef Kadlecsik <kadlec@xxxxxxxxxxxxx>, Florian Westphal <fw@xxxxxxxxx>, Roopa Prabhu <roopa@xxxxxxxxxx>, Nikolay Aleksandrov <razor@xxxxxxxxxxxxx>, Simon Horman <horms@xxxxxxxxxxxx>, Julian Anastasov <ja@xxxxxx>, Joerg Reuter <jreuter@xxxxxxxx>, Luis Chamberlain <mcgrof@xxxxxxxxxx>, Kees Cook <keescook@xxxxxxxxxxxx>
Subject: [PATCH net-next v6 8/8] ax.25: x.25: Remove the now superfluous sentinel elements from ctl_table array
Cc: netdev@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, dccp@xxxxxxxxxxxxxxx, linux-wpan@xxxxxxxxxxxxxxx, mptcp@xxxxxxxxxxxxxxx, linux-hams@xxxxxxxxxxxxxxx, linux-rdma@xxxxxxxxxxxxxxx, rds-devel@xxxxxxxxxxxxxx, linux-afs@xxxxxxxxxxxxxxxxxxx, linux-sctp@xxxxxxxxxxxxxxx, linux-s390@xxxxxxxxxxxxxxx, linux-nfs@xxxxxxxxxxxxxxx, tipc-discussion@xxxxxxxxxxxxxxxxxxxxx, linux-x25@xxxxxxxxxxxxxxx, netfilter-devel@xxxxxxxxxxxxxxx, coreteam@xxxxxxxxxxxxx, bridge@xxxxxxxxxxxxxxx, lvs-devel@xxxxxxxxxxxxxxx, Joel Granados <j.granados@xxxxxxxxxxx>
From: Joel Granados via B4 Relay <devnull+j.granados.samsung.com@xxxxxxxxxx>
Date: Wed, 01 May 2024 11:29:32 +0200
From: Joel Granados <j.granados@xxxxxxxxxxx>

This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which will
reduce the overall build time size of the kernel and run time memory
bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@xxxxxxxxxxxxxxxxxxxxxx/)

Avoid a buffer overflow when traversing the ctl_table by ensuring that
AX25_MAX_VALUES is the same as the size of ax25_param_table. This is
done with a BUILD_BUG_ON where ax25_param_table is defined and a
CONFIG_AX25_DAMA_SLAVE guard in the unnamed enum definition as well as
in the ax25_dev_device_up and ax25_ds_set_timer functions.

The overflow happened when the sentinel was removed from
ax25_param_table. The sentinel's data element was changed when
CONFIG_AX25_DAMA_SLAVE was undefined. This had no adverse effects as it
still stopped on the sentinel's null procname but needed to be addressed
once the sentinel was removed.

Signed-off-by: Joel Granados <j.granados@xxxxxxxxxxx>
---
 include/net/ax25.h         | 2 ++
 net/ax25/ax25_dev.c        | 3 +++
 net/ax25/ax25_ds_timer.c   | 1 +
 net/ax25/sysctl_net_ax25.c | 3 +--
 net/x25/sysctl_net_x25.c   | 1 -
 5 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/include/net/ax25.h b/include/net/ax25.h
index 0d939e5aee4e..eb9cee8252c8 100644
--- a/include/net/ax25.h
+++ b/include/net/ax25.h
@@ -139,7 +139,9 @@ enum {
        AX25_VALUES_N2,         /* Default N2 value */
        AX25_VALUES_PACLEN,     /* AX.25 MTU */
        AX25_VALUES_PROTOCOL,   /* Std AX.25, DAMA Slave, DAMA Master */
+#ifdef CONFIG_AX25_DAMA_SLAVE
        AX25_VALUES_DS_TIMEOUT, /* DAMA Slave timeout */
+#endif
        AX25_MAX_VALUES         /* THIS MUST REMAIN THE LAST ENTRY OF THIS LIST 
*/
 };
 
diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c
index 282ec581c072..0bc682ffae9c 100644
--- a/net/ax25/ax25_dev.c
+++ b/net/ax25/ax25_dev.c
@@ -78,7 +78,10 @@ void ax25_dev_device_up(struct net_device *dev)
        ax25_dev->values[AX25_VALUES_N2]        = AX25_DEF_N2;
        ax25_dev->values[AX25_VALUES_PACLEN]    = AX25_DEF_PACLEN;
        ax25_dev->values[AX25_VALUES_PROTOCOL]  = AX25_DEF_PROTOCOL;
+
+#ifdef CONFIG_AX25_DAMA_SLAVE
        ax25_dev->values[AX25_VALUES_DS_TIMEOUT]= AX25_DEF_DS_TIMEOUT;
+#endif
 
 #if defined(CONFIG_AX25_DAMA_SLAVE) || defined(CONFIG_AX25_DAMA_MASTER)
        ax25_ds_setup_timer(ax25_dev);
diff --git a/net/ax25/ax25_ds_timer.c b/net/ax25/ax25_ds_timer.c
index c4f8adbf8144..c50a58d9e368 100644
--- a/net/ax25/ax25_ds_timer.c
+++ b/net/ax25/ax25_ds_timer.c
@@ -55,6 +55,7 @@ void ax25_ds_set_timer(ax25_dev *ax25_dev)
        ax25_dev->dama.slave_timeout =
                msecs_to_jiffies(ax25_dev->values[AX25_VALUES_DS_TIMEOUT]) / 10;
        mod_timer(&ax25_dev->dama.slave_timer, jiffies + HZ);
+       return;
 }
 
 /*
diff --git a/net/ax25/sysctl_net_ax25.c b/net/ax25/sysctl_net_ax25.c
index e0128dc9def3..68753aa30334 100644
--- a/net/ax25/sysctl_net_ax25.c
+++ b/net/ax25/sysctl_net_ax25.c
@@ -141,8 +141,6 @@ static const struct ctl_table ax25_param_table[] = {
                .extra2         = &max_ds_timeout
        },
 #endif
-
-       { }     /* that's all, folks! */
 };
 
 int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
@@ -155,6 +153,7 @@ int ax25_register_dev_sysctl(ax25_dev *ax25_dev)
        if (!table)
                return -ENOMEM;
 
+       BUILD_BUG_ON(ARRAY_SIZE(ax25_param_table) != AX25_MAX_VALUES);
        for (k = 0; k < AX25_MAX_VALUES; k++)
                table[k].data = &ax25_dev->values[k];
 
diff --git a/net/x25/sysctl_net_x25.c b/net/x25/sysctl_net_x25.c
index e9802afa43d0..643f50874dfe 100644
--- a/net/x25/sysctl_net_x25.c
+++ b/net/x25/sysctl_net_x25.c
@@ -71,7 +71,6 @@ static struct ctl_table x25_table[] = {
                .mode =         0644,
                .proc_handler = proc_dointvec,
        },
-       { },
 };
 
 int __init x25_register_sysctl(void)

-- 
2.43.0




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