Re: [PATCH] sysctl: some input constraints checks were added for/proc/sys/vm directory

From: Petr Holasek
Date: Fri Mar 04 2011 - 06:14:56 EST


----- Original Message -----
> From: "Petr Holasek" <pholasek@xxxxxxxxxx>
> To: linux-kernel@xxxxxxxxxxxxxxx
> Cc: anton@xxxxxxxxxx, "Petr Holasek" <pholasek@xxxxxxxxxx>, "Alexander Viro" <viro@xxxxxxxxxxxxxxxxxx>, "Andrew
> Morton" <akpm@xxxxxxxxxxxxxxxxxxxx>, "Ingo Molnar" <mingo@xxxxxxx>, "Dave Young" <hidave.darkstar@xxxxxxxxx>, "David
> Miller" <davem@xxxxxxxxxxxxx>, "Don Zickus" <dzickus@xxxxxxxxxx>, linux-fsdevel@xxxxxxxxxxxxxxx
> Sent: Wednesday, March 2, 2011 5:16:14 PM
> Subject: [PATCH] sysctl: some input constraints checks were added for /proc/sys/vm directory
> There were added 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@xxxxxxxxxx>
> ---
> fs/drop_caches.c | 6 +++++-
> kernel/sysctl.c | 17 +++++++++++++----
> 2 files changed, 18 insertions(+), 5 deletions(-)
>
> diff --git a/fs/drop_caches.c b/fs/drop_caches.c
> index 2195c21..8e61858 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 0f1bd83..e0a4d50 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
> @@ -978,14 +979,18 @@ 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",
> @@ -1013,7 +1018,8 @@ 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",
> @@ -1061,7 +1067,8 @@ 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",
> @@ -1137,6 +1144,8 @@ static struct ctl_table vm_table[] = {
> .maxlen = sizeof(int),
> .mode = 0644,
> .proc_handler = drop_caches_sysctl_handler,
> + .extra1 = &one,
> + .extra2 = &three,
> },
> #ifdef CONFIG_COMPACTION
> {
> --
> 1.7.1
>
> --
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Apologize for the space/tabs mess, thanks to Dave Young for the warning,
corrected version here:

---
fs/drop_caches.c | 6 +++++-
kernel/sysctl.c | 17 +++++++++++++----
2 files changed, 18 insertions(+), 5 deletions(-)

diff --git a/fs/drop_caches.c b/fs/drop_caches.c
index 2195c21..8e61858 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 0f1bd83..e0a4d50 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
@@ -978,14 +979,18 @@ 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",
@@ -1013,7 +1018,8 @@ 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",
@@ -1061,7 +1067,8 @@ 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",
@@ -1137,6 +1144,8 @@ static struct ctl_table vm_table[] = {
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = drop_caches_sysctl_handler,
+ .extra1 = &one,
+ .extra2 = &three,
},
#ifdef CONFIG_COMPACTION
{
--
1.7.1
--
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