X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=blobdiff_plain;f=kernel%2Fptrace.c;h=705887f63288d4694c5bccd5c77900cbddc1f843;hb=060157e1dbc133075a2e20786d6ff6d4b41909f9;hp=5710d07e67cf7f0f94342b0194939d479871b821;hpb=b21e31b253048b7f9768ca7cc270e67765fd6ba2;p=linux.git

diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 5710d07e67cf..705887f63288 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -79,9 +79,7 @@ void __ptrace_link(struct task_struct *child, struct task_struct *new_parent,
  */
 static void ptrace_link(struct task_struct *child, struct task_struct *new_parent)
 {
-	rcu_read_lock();
-	__ptrace_link(child, new_parent, __task_cred(new_parent));
-	rcu_read_unlock();
+	__ptrace_link(child, new_parent, current_cred());
 }
 
 /**
@@ -324,6 +322,16 @@ static int __ptrace_may_access(struct task_struct *task, unsigned int mode)
 	return -EPERM;
 ok:
 	rcu_read_unlock();
+	/*
+	 * If a task drops privileges and becomes nondumpable (through a syscall
+	 * like setresuid()) while we are trying to access it, we must ensure
+	 * that the dumpability is read after the credentials; otherwise,
+	 * we may be able to attach to a task that we shouldn't be able to
+	 * attach to (as if the task had dropped privileges without becoming
+	 * nondumpable).
+	 * Pairs with a write barrier in commit_creds().
+	 */
+	smp_rmb();
 	mm = task->mm;
 	if (mm &&
 	    ((get_dumpable(mm) != SUID_DUMP_USER) &&
@@ -705,6 +713,10 @@ static int ptrace_peek_siginfo(struct task_struct *child,
 	if (arg.nr < 0)
 		return -EINVAL;
 
+	/* Ensure arg.off fits in an unsigned long */
+	if (arg.off > ULONG_MAX)
+		return 0;
+
 	if (arg.flags & PTRACE_PEEKSIGINFO_SHARED)
 		pending = &child->signal->shared_pending;
 	else
@@ -712,18 +724,20 @@ static int ptrace_peek_siginfo(struct task_struct *child,
 
 	for (i = 0; i < arg.nr; ) {
 		kernel_siginfo_t info;
-		s32 off = arg.off + i;
+		unsigned long off = arg.off + i;
+		bool found = false;
 
 		spin_lock_irq(&child->sighand->siglock);
 		list_for_each_entry(q, &pending->list, list) {
 			if (!off--) {
+				found = true;
 				copy_siginfo(&info, &q->info);
 				break;
 			}
 		}
 		spin_unlock_irq(&child->sighand->siglock);
 
-		if (off >= 0) /* beyond the end of the list */
+		if (!found) /* beyond the end of the list */
 			break;
 
 #ifdef CONFIG_COMPAT