diff options
| author | David Howells <dhowells@redhat.com> | 2008-09-05 23:15:58 +1000 |
|---|---|---|
| committer | James Morris <jmorris@namei.org> | 2008-09-05 23:15:58 +1000 |
| commit | e3c5b08cf35d6e1913789255e0755dfb46cc0807 (patch) | |
| tree | 584a23489a71fa0f1ca7452b78bbacfbe9543bbc /mm/mempolicy.c | |
| parent | 4865969c64ed7e911fae4e6a275e65789806f823 (diff) | |
CRED: Use RCU to access another task's creds and to release a task's own creds
Use RCU to access another task's creds and to release a task's own creds.
This means that it will be possible for the credentials of a task to be
replaced without another task (a) requiring a full lock to read them, and (b)
seeing deallocated memory.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: James Morris <jmorris@namei.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'mm/mempolicy.c')
| -rw-r--r-- | mm/mempolicy.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 09d9fc3dee6a..9bc3bc7cc00b 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1105,7 +1105,7 @@ asmlinkage long sys_migrate_pages(pid_t pid, unsigned long maxnode, const unsigned long __user *old_nodes, const unsigned long __user *new_nodes) { - struct cred *cred, *tcred; + const struct cred *cred = current_cred(), *tcred; struct mm_struct *mm; struct task_struct *task; nodemask_t old; @@ -1140,14 +1140,16 @@ asmlinkage long sys_migrate_pages(pid_t pid, unsigned long maxnode, * capabilities, superuser privileges or the same * userid as the target process. */ - cred = current->cred; - tcred = task->cred; + rcu_read_lock(); + tcred = __task_cred(task); if (cred->euid != tcred->suid && cred->euid != tcred->uid && cred->uid != tcred->suid && cred->uid != tcred->uid && !capable(CAP_SYS_NICE)) { + rcu_read_unlock(); err = -EPERM; goto out; } + rcu_read_unlock(); task_nodes = cpuset_mems_allowed(task); /* Is the user allowed to access the target nodes? */ |