From: Oleg Nesterov Date: Mon, 23 Dec 2013 22:45:01 +0000 (-0500) Subject: selinux: selinux_setprocattr()->ptrace_parent() needs rcu_read_lock() X-Git-Tag: v3.12.7~122 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=3a3f7cfe5c16170aeb0dd2654f464cfbd2332b1d;p=thirdparty%2Fkernel%2Fstable.git selinux: selinux_setprocattr()->ptrace_parent() needs rcu_read_lock() commit c0c1439541f5305b57a83d599af32b74182933fe upstream. selinux_setprocattr() does ptrace_parent(p) under task_lock(p), but task_struct->alloc_lock doesn't pin ->parent or ->ptrace, this looks confusing and triggers the "suspicious RCU usage" warning because ptrace_parent() does rcu_dereference_check(). And in theory this is wrong, spin_lock()->preempt_disable() doesn't necessarily imply rcu_read_lock() we need to access the ->parent. Reported-by: Evan McNabb Signed-off-by: Oleg Nesterov Signed-off-by: Paul Moore Signed-off-by: Greg Kroah-Hartman --- diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 788586e3b7043..d529962a60e8a 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -5523,11 +5523,11 @@ static int selinux_setprocattr(struct task_struct *p, /* Check for ptracing, and update the task SID if ok. Otherwise, leave SID unchanged and fail. */ ptsid = 0; - task_lock(p); + rcu_read_lock(); tracer = ptrace_parent(p); if (tracer) ptsid = task_sid(tracer); - task_unlock(p); + rcu_read_unlock(); if (tracer) { error = avc_has_perm(ptsid, sid, SECCLASS_PROCESS,