sysctl: add some missing input constraint checks

Add boundaries of allowed input ranges for: dirty_expire_centisecs,
drop_caches, overcommit_memory, page-cluster and panic_on_oom.

Signed-off-by: Petr Holasek <pholasek@redhat.com>
Acked-by: Dave Young <hidave.darkstar@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 18 insertions, 5 deletions

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index 2195c213ab2f..816f88e6b9ce 100644
--- a/fs/drop_caches.c
+++ b/fs/drop_caches.c
@@ -45,7 +45,11 @@ static void drop_slab(void)
 int drop_caches_sysctl_handler(ctl_table *table, int write,
         void __user *buffer, size_t *length, loff_t *ppos)
 {
-        proc_dointvec_minmax(table, write, buffer, length, ppos);
+        int ret;
+
+        ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
+        if (ret)
+                return ret;
         if (write) {
                 if (sysctl_drop_caches & 1)
                         iterate_supers(drop_pagecache_sb, NULL);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 40245d697602..97ab1690f5ed 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -117,6 +117,7 @@ static int neg_one = -1;
 static int zero;
 static int __maybe_unused one = 1;
 static int __maybe_unused two = 2;
+static int __maybe_unused three = 3;
 static unsigned long one_ul = 1;
 static int one_hundred = 100;
 #ifdef CONFIG_PRINTK
@@ -971,14 +972,18 @@ static struct ctl_table vm_table[] = {
                 .data           = &sysctl_overcommit_memory,
                 .maxlen         = sizeof(sysctl_overcommit_memory),
                 .mode           = 0644,
-                .proc_handler   = proc_dointvec,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &zero,
+                .extra2         = &two,
         },
         {
                 .procname       = "panic_on_oom",
                 .data           = &sysctl_panic_on_oom,
                 .maxlen         = sizeof(sysctl_panic_on_oom),
                 .mode           = 0644,
-                .proc_handler   = proc_dointvec,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &zero,
+                .extra2         = &two,
         },
         {
                 .procname       = "oom_kill_allocating_task",
@@ -1006,7 +1011,8 @@ static struct ctl_table vm_table[] = {
                 .data           = &page_cluster,
                 .maxlen         = sizeof(int),
                 .mode           = 0644,
-                .proc_handler   = proc_dointvec,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &zero,
         },
         {
                 .procname       = "dirty_background_ratio",
@@ -1054,7 +1060,8 @@ static struct ctl_table vm_table[] = {
                 .data           = &dirty_expire_interval,
                 .maxlen         = sizeof(dirty_expire_interval),
                 .mode           = 0644,
-                .proc_handler   = proc_dointvec,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &zero,
         },
         {
                 .procname       = "nr_pdflush_threads",
@@ -1130,6 +1137,8 @@ static struct ctl_table vm_table[] = {
                 .maxlen         = sizeof(int),
                 .mode           = 0644,
                 .proc_handler   = drop_caches_sysctl_handler,
+                .extra1         = &one,
+                .extra2         = &three,
         },
 #ifdef CONFIG_COMPACTION
         {