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* [PATCH] sched/fair: Null terminate buffer when updating tunable_scaling
@ 2021-09-27 11:46 Mel Gorman
  2021-09-27 16:50 ` Vincent Guittot
  2021-10-01 12:10 ` [tip: sched/urgent] " tip-bot2 for Mel Gorman
  0 siblings, 2 replies; 3+ messages in thread
From: Mel Gorman @ 2021-09-27 11:46 UTC (permalink / raw)
  To: Peter Zijlstra
  Cc: Mike Galbraith, Ingo Molnar, Valentin Schneider, Vincent Guittot, LKML

This patch null-terminates the temporary buffer in sched_scaling_write()
so kstrtouint() does not return failure and checks the value is valid.

Before
$ cat /sys/kernel/debug/sched/tunable_scaling
1
$ echo 0 > /sys/kernel/debug/sched/tunable_scaling
-bash: echo: write error: Invalid argument
$ cat /sys/kernel/debug/sched/tunable_scaling
1

After
$ cat /sys/kernel/debug/sched/tunable_scaling
1
$ echo 0 > /sys/kernel/debug/sched/tunable_scaling
$ cat /sys/kernel/debug/sched/tunable_scaling
0
$ echo 3 > /sys/kernel/debug/sched/tunable_scaling
-bash: echo: write error: Invalid argument

Fixes: 8a99b6833c88 ("sched: Move SCHED_DEBUG sysctl to debugfs")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
---
 kernel/sched/debug.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 49716228efb4..17a653b67006 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -173,16 +173,22 @@ static ssize_t sched_scaling_write(struct file *filp, const char __user *ubuf,
 				   size_t cnt, loff_t *ppos)
 {
 	char buf[16];
+	unsigned int scaling;
 
 	if (cnt > 15)
 		cnt = 15;
 
 	if (copy_from_user(&buf, ubuf, cnt))
 		return -EFAULT;
+	buf[cnt] = '\0';
 
-	if (kstrtouint(buf, 10, &sysctl_sched_tunable_scaling))
+	if (kstrtouint(buf, 10, &scaling))
 		return -EINVAL;
 
+	if (scaling >= SCHED_TUNABLESCALING_END)
+		return -EINVAL;
+
+	sysctl_sched_tunable_scaling = scaling;
 	if (sched_update_scaling())
 		return -EINVAL;
 

^ permalink raw reply related	[flat|nested] 3+ messages in thread
* Re: [PATCH] sched/fair: Null terminate buffer when updating tunable_scaling
  2021-09-27 11:46 [PATCH] sched/fair: Null terminate buffer when updating tunable_scaling Mel Gorman
@ 2021-09-27 16:50 ` Vincent Guittot
  2021-10-01 12:10 ` [tip: sched/urgent] " tip-bot2 for Mel Gorman
  1 sibling, 0 replies; 3+ messages in thread
From: Vincent Guittot @ 2021-09-27 16:50 UTC (permalink / raw)
  To: Mel Gorman
  Cc: Peter Zijlstra, Mike Galbraith, Ingo Molnar, Valentin Schneider, LKML

On Mon, 27 Sept 2021 at 13:46, Mel Gorman <mgorman@techsingularity.net> wrote:
>
> This patch null-terminates the temporary buffer in sched_scaling_write()
> so kstrtouint() does not return failure and checks the value is valid.
>
> Before
> $ cat /sys/kernel/debug/sched/tunable_scaling
> 1
> $ echo 0 > /sys/kernel/debug/sched/tunable_scaling
> -bash: echo: write error: Invalid argument
> $ cat /sys/kernel/debug/sched/tunable_scaling
> 1
>
> After
> $ cat /sys/kernel/debug/sched/tunable_scaling
> 1
> $ echo 0 > /sys/kernel/debug/sched/tunable_scaling
> $ cat /sys/kernel/debug/sched/tunable_scaling
> 0
> $ echo 3 > /sys/kernel/debug/sched/tunable_scaling
> -bash: echo: write error: Invalid argument
>
> Fixes: 8a99b6833c88 ("sched: Move SCHED_DEBUG sysctl to debugfs")
> Signed-off-by: Mel Gorman <mgorman@techsingularity.net>

Acked-by: Vincent Guittot <vincent.guittot@linaro.org>

> ---
>  kernel/sched/debug.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
> index 49716228efb4..17a653b67006 100644
> --- a/kernel/sched/debug.c
> +++ b/kernel/sched/debug.c
> @@ -173,16 +173,22 @@ static ssize_t sched_scaling_write(struct file *filp, const char __user *ubuf,
>                                    size_t cnt, loff_t *ppos)
>  {
>         char buf[16];
> +       unsigned int scaling;
>
>         if (cnt > 15)
>                 cnt = 15;
>
>         if (copy_from_user(&buf, ubuf, cnt))
>                 return -EFAULT;
> +       buf[cnt] = '\0';
>
> -       if (kstrtouint(buf, 10, &sysctl_sched_tunable_scaling))
> +       if (kstrtouint(buf, 10, &scaling))
>                 return -EINVAL;
>
> +       if (scaling >= SCHED_TUNABLESCALING_END)
> +               return -EINVAL;
> +
> +       sysctl_sched_tunable_scaling = scaling;
>         if (sched_update_scaling())
>                 return -EINVAL;
>

^ permalink raw reply	[flat|nested] 3+ messages in thread
* [tip: sched/urgent] sched/fair: Null terminate buffer when updating tunable_scaling
  2021-09-27 11:46 [PATCH] sched/fair: Null terminate buffer when updating tunable_scaling Mel Gorman
  2021-09-27 16:50 ` Vincent Guittot
@ 2021-10-01 12:10 ` tip-bot2 for Mel Gorman
  1 sibling, 0 replies; 3+ messages in thread
From: tip-bot2 for Mel Gorman @ 2021-10-01 12:10 UTC (permalink / raw)
  To: linux-tip-commits
  Cc: Mel Gorman, Peter Zijlstra (Intel), Vincent Guittot, x86, linux-kernel

The following commit has been merged into the sched/urgent branch of tip:

Commit-ID:     703066188f63d66cc6b9d678e5b5ef1213c5938e
Gitweb:        https://git.kernel.org/tip/703066188f63d66cc6b9d678e5b5ef1213c5938e
Author:        Mel Gorman <mgorman@techsingularity.net>
AuthorDate:    Mon, 27 Sep 2021 12:46:35 +01:00
Committer:     Peter Zijlstra <peterz@infradead.org>
CommitterDate: Fri, 01 Oct 2021 13:57:57 +02:00

sched/fair: Null terminate buffer when updating tunable_scaling

This patch null-terminates the temporary buffer in sched_scaling_write()
so kstrtouint() does not return failure and checks the value is valid.

Before:
  $ cat /sys/kernel/debug/sched/tunable_scaling
  1
  $ echo 0 > /sys/kernel/debug/sched/tunable_scaling
  -bash: echo: write error: Invalid argument
  $ cat /sys/kernel/debug/sched/tunable_scaling
  1

After:
  $ cat /sys/kernel/debug/sched/tunable_scaling
  1
  $ echo 0 > /sys/kernel/debug/sched/tunable_scaling
  $ cat /sys/kernel/debug/sched/tunable_scaling
  0
  $ echo 3 > /sys/kernel/debug/sched/tunable_scaling
  -bash: echo: write error: Invalid argument

Fixes: 8a99b6833c88 ("sched: Move SCHED_DEBUG sysctl to debugfs")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20210927114635.GH3959@techsingularity.net
---
 kernel/sched/debug.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c
index 4971622..17a653b 100644
--- a/kernel/sched/debug.c
+++ b/kernel/sched/debug.c
@@ -173,16 +173,22 @@ static ssize_t sched_scaling_write(struct file *filp, const char __user *ubuf,
 				   size_t cnt, loff_t *ppos)
 {
 	char buf[16];
+	unsigned int scaling;
 
 	if (cnt > 15)
 		cnt = 15;
 
 	if (copy_from_user(&buf, ubuf, cnt))
 		return -EFAULT;
+	buf[cnt] = '\0';
 
-	if (kstrtouint(buf, 10, &sysctl_sched_tunable_scaling))
+	if (kstrtouint(buf, 10, &scaling))
 		return -EINVAL;
 
+	if (scaling >= SCHED_TUNABLESCALING_END)
+		return -EINVAL;
+
+	sysctl_sched_tunable_scaling = scaling;
 	if (sched_update_scaling())
 		return -EINVAL;
 

^ permalink raw reply related	[flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-10-01 12:10 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-09-27 11:46 [PATCH] sched/fair: Null terminate buffer when updating tunable_scaling Mel Gorman
2021-09-27 16:50 ` Vincent Guittot
2021-10-01 12:10 ` [tip: sched/urgent] " tip-bot2 for Mel Gorman

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