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authorDavid Howells <dhowells@redhat.com>2008-11-14 10:39:19 +1100
committerJames Morris <jmorris@namei.org>2008-11-14 10:39:19 +1100
commitc69e8d9c01db2adc503464993c358901c9af9de4 (patch)
treebed94aaa9aeb7a7834d1c880f72b62a11a752c78 /arch/ia64/kernel/perfmon.c
parent86a264abe542cfececb4df129bc45a0338d8cdb9 (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 'arch/ia64/kernel/perfmon.c')
-rw-r--r--arch/ia64/kernel/perfmon.c32
1 files changed, 20 insertions, 12 deletions
diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c
index dd38db46a77..0e499757309 100644
--- a/arch/ia64/kernel/perfmon.c
+++ b/arch/ia64/kernel/perfmon.c
@@ -2399,25 +2399,33 @@ error_kmem:
static int
pfm_bad_permissions(struct task_struct *task)
{
+ const struct cred *tcred;
uid_t uid = current_uid();
gid_t gid = current_gid();
+ int ret;
+
+ rcu_read_lock();
+ tcred = __task_cred(task);
/* inspired by ptrace_attach() */
DPRINT(("cur: uid=%d gid=%d task: euid=%d suid=%d uid=%d egid=%d sgid=%d\n",
uid,
gid,
- task->euid,
- task->suid,
- task->uid,
- task->egid,
- task->sgid));
-
- return (uid != task->euid)
- || (uid != task->suid)
- || (uid != task->uid)
- || (gid != task->egid)
- || (gid != task->sgid)
- || (gid != task->gid)) && !capable(CAP_SYS_PTRACE);
+ tcred->euid,
+ tcred->suid,
+ tcred->uid,
+ tcred->egid,
+ tcred->sgid));
+
+ ret = ((uid != tcred->euid)
+ || (uid != tcred->suid)
+ || (uid != tcred->uid)
+ || (gid != tcred->egid)
+ || (gid != tcred->sgid)
+ || (gid != tcred->gid)) && !capable(CAP_SYS_PTRACE);
+
+ rcu_read_unlock();
+ return ret;
}
static int