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: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 8 deletions

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 71a34253dcbb..55c4c805a756 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1021,21 +1021,24 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
                                 size_t count, loff_t *ppos)
 {
         struct task_struct *task;
-        char buffer[PROC_NUMBUF], *end;
-        int oom_adjust;
+        char buffer[PROC_NUMBUF];
+        long oom_adjust;
         unsigned long flags;
+        int err;
 
         memset(buffer, 0, sizeof(buffer));
         if (count > sizeof(buffer) - 1)
                 count = sizeof(buffer) - 1;
         if (copy_from_user(buffer, buf, count))
                 return -EFAULT;
-        oom_adjust = simple_strtol(buffer, &end, 0);
+
+        err = strict_strtol(strstrip(buffer), 0, &oom_adjust);
+        if (err)
+                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;
@@ -1054,9 +1057,8 @@ static ssize_t oom_adjust_write(struct file *file, const char __user *buf,
 
         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 = {