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SubjectRe: [PATCH 4/4] oom: fix oom_adjust_write() input sanity check.
On Tue,  4 Aug 2009 19:28:03 +0900 (JST) KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

> Subject: [PATCH] oom: fix oom_adjust_write() input sanity check.
>
> Andrew Morton pointed out oom_adjust_write() has very strange EIO
> and new line handling. this patch fixes it.
>
>
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Cc: Paul Menage <menage@google.com>
> Cc: David Rientjes <rientjes@google.com>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Rik van Riel <riel@redhat.com>,
> Cc: Andrew Morton <akpm@linux-foundation.org>,
> ---
> fs/proc/base.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> Index: b/fs/proc/base.c
> ===================================================================
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -1033,12 +1033,15 @@ static ssize_t oom_adjust_write(struct f
> count = sizeof(buffer) - 1;
> if (copy_from_user(buffer, buf, count))
> return -EFAULT;
> +
> + strstrip(buffer);

+1 for using strstrip()

-1 for using it wrongly. If it strips leading whitespace it will
return a new address for the caller to use.

We could mark it __must_check() to prevent reoccurences of this error.

How does this look?

--- a/fs/proc/base.c~oom-fix-oom_adjust_write-input-sanity-check-fix
+++ a/fs/proc/base.c
@@ -1033,8 +1033,7 @@ static ssize_t oom_adjust_write(struct f
if (copy_from_user(buffer, buf, count))
return -EFAULT;

- strstrip(buffer);
- oom_adjust = simple_strtol(buffer, &end, 0);
+ oom_adjust = simple_strtol(strstrip(buffer), &end, 0);
if (*end)
return -EINVAL;
if ((oom_adjust < OOM_ADJUST_MIN || oom_adjust > OOM_ADJUST_MAX) &&

> oom_adjust = simple_strtol(buffer, &end, 0);

That should've used strict_strtoul() but it's too late to fix it now.

> + if (*end)
> + return -EINVAL;
> if ((oom_adjust < OOM_ADJUST_MIN || oom_adjust > OOM_ADJUST_MAX) &&
> oom_adjust != OOM_DISABLE)
> return -EINVAL;
> - if (*end == '\n')
> - end++;
> +
> task = get_proc_task(file->f_path.dentry->d_inode);
> if (!task)
> return -ESRCH;
> @@ -1057,9 +1060,8 @@ static ssize_t oom_adjust_write(struct f
> task->signal->oom_adj = oom_adjust;
> unlock_task_sighand(task, &flags);
> put_task_struct(task);
> - if (end - buffer == 0)
> - return -EIO;
> - return end - buffer;
> +
> + return count;
> }
>
> static const struct file_operations proc_oom_adjust_operations = {
>


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