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sched/fair: Null terminate buffer when updating tunable_scaling

PATCH Applied Mel Gorman 3 participants 3 messages Sep 27, 2021 – Oct 1, 2021 Scheduler

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Mel Gorman

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#0 lore raw

PATCH 1/1 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 <[email protected]>
---
 kernel/sched/debug.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
kernel/sched/debug.c +7 -1
index 49716228efb4..17a653b67006 100644
@@ -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;
maintainer Acked-by on v1 1/1
#1 lore raw
Quoted 21 lines · Mel Gorman

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
Quoted 2 lines
Fixes 8a99b6833c88 ("sched: Move SCHED_DEBUG sysctl to debugfs")
Signed-off-by Mel Gorman <[email protected]>
Acked-by Vincent Guittot <[email protected]>
Quoted 32 lines
---
 kernel/sched/debug.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
kernel/sched/debug.c +7 -1
index 49716228efb4..17a653b67006 100644
@@ -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;
merge bot Applied
#2 lore raw
In reply to Mel Gorman
The following commit has been merged into the sched/urgent branch of tip:

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 <[email protected]>
AuthorDate:    Mon, 27 Sep 2021 12:46:35 +01:00
Committer:     Peter Zijlstra <[email protected]>
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 <[email protected]>
Signed-off-by Peter Zijlstra (Intel) <[email protected]>
Acked-by Vincent Guittot <[email protected]>
Link https://lore.kernel.org/r/[email protected] open here
---
 kernel/sched/debug.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
kernel/sched/debug.c +7 -1
index 4971622..17a653b 100644
@@ -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;