[PATCH 05/11] sysctl: Add a size arg to __register_sysctl_table

[Joel Granados]

In order to remove the end element from the ctl_table struct arrays, we
explicitly define the size when registering the targets.
__register_sysctl_table is the first function to grow a size argument.
For this commit to focus only on that function, we temporarily implement
a size calculation in register_net_sysctl, which is an indirection call
for all the network register calls.

Signed-off-by: Joel Granados <j.granados@xxxxxxxxxxx>
---
 fs/proc/proc_sysctl.c  | 22 +++++++++++-----------
 include/linux/sysctl.h |  2 +-
 ipc/ipc_sysctl.c       |  4 +++-
 ipc/mq_sysctl.c        |  4 +++-
 kernel/ucount.c        |  3 ++-
 net/sysctl_net.c       |  8 +++++++-
 6 files changed, 27 insertions(+), 16 deletions(-)

diff --git a/fs/proc/proc_sysctl.c b/fs/proc/proc_sysctl.c
index 09c09c373624..8c415048d540 100644
--- a/fs/proc/proc_sysctl.c
+++ b/fs/proc/proc_sysctl.c
@@ -1354,27 +1354,20 @@ static struct ctl_dir *sysctl_mkdir_p(struct ctl_dir *dir, const char *path)
  */
 struct ctl_table_header *__register_sysctl_table(
 	struct ctl_table_set *set,
-	const char *path, struct ctl_table *table)
+	const char *path, struct ctl_table *table, size_t table_size)
 {
 	struct ctl_table_root *root = set->dir.header.root;
 	struct ctl_table_header *header;
-	struct ctl_table_header h_tmp;
 	struct ctl_dir *dir;
-	struct ctl_table *entry;
 	struct ctl_node *node;
-	int nr_entries = 0;
-
-	h_tmp.ctl_table = table;
-	list_for_each_table_entry(entry, (&h_tmp))
-		nr_entries++;
 
 	header = kzalloc(sizeof(struct ctl_table_header) +
-			 sizeof(struct ctl_node)*nr_entries, GFP_KERNEL_ACCOUNT);
+			 sizeof(struct ctl_node)*table_size, GFP_KERNEL_ACCOUNT);
 	if (!header)
 		return NULL;
 
 	node = (struct ctl_node *)(header + 1);
-	init_header(header, root, set, node, table, nr_entries);
+	init_header(header, root, set, node, table, table_size);
 	if (sysctl_check_table(path, header))
 		goto fail;
 
@@ -1423,8 +1416,15 @@ struct ctl_table_header *__register_sysctl_table(
  */
 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table)
 {
+	int count = 0;
+	struct ctl_table *entry;
+	struct ctl_table_header t_hdr;
+
+	t_hdr.ctl_table = table;
+	list_for_each_table_entry(entry, (&t_hdr))
+		count++;
 	return __register_sysctl_table(&sysctl_table_root.default_set,
-					path, table);
+					path, table, count);
 }
 EXPORT_SYMBOL(register_sysctl);
 
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 33252ad58ebe..0495c858989f 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -226,7 +226,7 @@ extern void retire_sysctl_set(struct ctl_table_set *set);
 
 struct ctl_table_header *__register_sysctl_table(
 	struct ctl_table_set *set,
-	const char *path, struct ctl_table *table);
+	const char *path, struct ctl_table *table, size_t table_size);
 struct ctl_table_header *register_sysctl(const char *path, struct ctl_table *table);
 void unregister_sysctl_table(struct ctl_table_header * table);
 
diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index ef313ecfb53a..8c62e443f78b 100644
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c
@@ -259,7 +259,9 @@ bool setup_ipc_sysctls(struct ipc_namespace *ns)
 				tbl[i].data = NULL;
 		}
 
-		ns->ipc_sysctls = __register_sysctl_table(&ns->ipc_set, "kernel", tbl);
+		ns->ipc_sysctls = __register_sysctl_table(&ns->ipc_set,
+							  "kernel", tbl,
+							  ARRAY_SIZE(ipc_sysctls));
 	}
 	if (!ns->ipc_sysctls) {
 		kfree(tbl);
diff --git a/ipc/mq_sysctl.c b/ipc/mq_sysctl.c
index fbf6a8b93a26..ebb5ed81c151 100644
--- a/ipc/mq_sysctl.c
+++ b/ipc/mq_sysctl.c
@@ -109,7 +109,9 @@ bool setup_mq_sysctls(struct ipc_namespace *ns)
 				tbl[i].data = NULL;
 		}
 
-		ns->mq_sysctls = __register_sysctl_table(&ns->mq_set, "fs/mqueue", tbl);
+		ns->mq_sysctls = __register_sysctl_table(&ns->mq_set,
+							 "fs/mqueue", tbl,
+							 ARRAY_SIZE(mq_sysctls));
 	}
 	if (!ns->mq_sysctls) {
 		kfree(tbl);
diff --git a/kernel/ucount.c b/kernel/ucount.c
index ee8e57fd6f90..2b80264bb79f 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -104,7 +104,8 @@ bool setup_userns_sysctls(struct user_namespace *ns)
 		for (i = 0; i < UCOUNT_COUNTS; i++) {
 			tbl[i].data = &ns->ucount_max[i];
 		}
-		ns->sysctls = __register_sysctl_table(&ns->set, "user", tbl);
+		ns->sysctls = __register_sysctl_table(&ns->set, "user", tbl,
+						      ARRAY_SIZE(user_table));
 	}
 	if (!ns->sysctls) {
 		kfree(tbl);
diff --git a/net/sysctl_net.c b/net/sysctl_net.c
index 4b45ed631eb8..8ee4b74bc009 100644
--- a/net/sysctl_net.c
+++ b/net/sysctl_net.c
@@ -163,10 +163,16 @@ static void ensure_safe_net_sysctl(struct net *net, const char *path,
 struct ctl_table_header *register_net_sysctl(struct net *net,
 	const char *path, struct ctl_table *table)
 {
+	int count = 0;
+	struct ctl_table *entry;
+
 	if (!net_eq(net, &init_net))
 		ensure_safe_net_sysctl(net, path, table);
 
-	return __register_sysctl_table(&net->sysctls, path, table);
+	for (entry = table; entry->procname; entry++)
+		count++;
+
+	return __register_sysctl_table(&net->sysctls, path, table, count);
 }
 EXPORT_SYMBOL_GPL(register_net_sysctl);
 
-- 
2.30.2