Right now there is a hole in the module ref counting system because
there is no proper ref counting for sysctl tables used by modules.
This means that if an application is holding /proc/sys/foo open and
module that created it is unloaded, then the application touches the
file the kernel will oops.
This patch fixes that by maintaining source compatibility via macro.
I am sure someone already thought of this, it just doesn't appear to
have made it in yet.
Signed-off-by: Stephen Hemminger <[email protected]>
--- net-2.6.16.orig/include/linux/sysctl.h
+++ net-2.6.16/include/linux/sysctl.h
@@ -21,6 +21,7 @@
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/compiler.h>
+#include <linux/module.h>
struct file;
struct completion;
@@ -973,9 +974,13 @@ struct ctl_table_header
struct completion *unregistering;
};
-struct ctl_table_header * register_sysctl_table(ctl_table * table,
- int insert_at_head);
-void unregister_sysctl_table(struct ctl_table_header * table);
+extern struct ctl_table_header *__register_sysctl_table(ctl_table * table,
+ struct module *owner,
+ int insert_at_head);
+#define register_sysctl_table(table, insert_at_head) \
+ __register_sysctl_table(table, THIS_MODULE, insert_at_head)
+
+extern void unregister_sysctl_table(struct ctl_table_header * table);
#else /* __KERNEL__ */
--- net-2.6.16.orig/kernel/sysctl.c
+++ net-2.6.16/kernel/sysctl.c
@@ -169,7 +169,8 @@ struct file_operations proc_sys_file_ope
extern struct proc_dir_entry *proc_sys_root;
-static void register_proc_table(ctl_table *, struct proc_dir_entry *, void *);
+static void register_proc_table(ctl_table *, struct proc_dir_entry *, void *,
+ struct module *);
static void unregister_proc_table(ctl_table *, struct proc_dir_entry *);
#endif
@@ -1036,7 +1037,7 @@ static void start_unregistering(struct c
void __init sysctl_init(void)
{
#ifdef CONFIG_PROC_FS
- register_proc_table(root_table, proc_sys_root, &root_table_header);
+ register_proc_table(root_table, proc_sys_root, &root_table_header, NULL);
init_irq_proc();
#endif
}
@@ -1279,8 +1280,9 @@ int do_sysctl_strategy (ctl_table *table
* This routine returns %NULL on a failure to register, and a pointer
* to the table header on success.
*/
-struct ctl_table_header *register_sysctl_table(ctl_table * table,
- int insert_at_head)
+struct ctl_table_header *__register_sysctl_table(ctl_table * table,
+ struct module *owner,
+ int insert_at_head)
{
struct ctl_table_header *tmp;
tmp = kmalloc(sizeof(struct ctl_table_header), GFP_KERNEL);
@@ -1297,7 +1299,7 @@ struct ctl_table_header *register_sysctl
list_add_tail(&tmp->ctl_entry, &root_table_header.ctl_entry);
spin_unlock(&sysctl_lock);
#ifdef CONFIG_PROC_FS
- register_proc_table(table, proc_sys_root, tmp);
+ register_proc_table(table, proc_sys_root, tmp, owner);
#endif
return tmp;
}
@@ -1328,7 +1330,8 @@ void unregister_sysctl_table(struct ctl_
#ifdef CONFIG_PROC_FS
/* Scan the sysctl entries in table and add them all into /proc */
-static void register_proc_table(ctl_table * table, struct proc_dir_entry *root, void *set)
+static void register_proc_table(ctl_table * table, struct proc_dir_entry *root,
+ void *set, struct module *owner)
{
struct proc_dir_entry *de;
int len;
@@ -1366,12 +1369,13 @@ static void register_proc_table(ctl_tabl
continue;
de->set = set;
de->data = (void *) table;
+ de->owner = owner;
if (table->proc_handler)
de->proc_fops = &proc_sys_file_operations;
}
table->de = de;
if (de->mode & S_IFDIR)
- register_proc_table(table->child, de, set);
+ register_proc_table(table->child, de, set, owner);
}
}
@@ -2414,8 +2418,9 @@ int proc_doulongvec_ms_jiffies_minmax(ct
return -ENOSYS;
}
-struct ctl_table_header * register_sysctl_table(ctl_table * table,
- int insert_at_head)
+struct ctl_table_header * __register_sysctl_table(ctl_table * table,
+ struct module *owner,
+ int insert_at_head)
{
return NULL;
}
@@ -2438,7 +2443,7 @@ EXPORT_SYMBOL(proc_dointvec_ms_jiffies);
EXPORT_SYMBOL(proc_dostring);
EXPORT_SYMBOL(proc_doulongvec_minmax);
EXPORT_SYMBOL(proc_doulongvec_ms_jiffies_minmax);
-EXPORT_SYMBOL(register_sysctl_table);
+EXPORT_SYMBOL(__register_sysctl_table);
EXPORT_SYMBOL(sysctl_intvec);
EXPORT_SYMBOL(sysctl_jiffies);
EXPORT_SYMBOL(sysctl_ms_jiffies);
-
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