DTrace MFC broke kldstat(2) on RELENG_7

[Jaakko Heinonen]

Hi,

I recently noticed that kldstat(8) started to dump core for me on
RELENG_7. I traced the problem down to kldstat(2). r182231 (DTrace
MFC) introduced a new version of kld_file_stat struct and added some
code to support the old version of the structure in kldstat(). In the
new code the old structure is known as kld_file_stat_1. Unfortunately
there's a bug in this code: kldstat() copies always sizeof(struct
kld_file_stat) of data to user space while it should copy sizeof(struct
kld_file_stat_1) when the old struct is used.

This guy is probably suffering from this problem too:
http://lists.freebsd.org/pipermail/freebsd-questions/2008-September/182896.html

I used this patch to fix the problem:

%%%
Index: sys/kern/kern_linker.c
===================================================================
--- sys/kern/kern_linker.c	(revision 183486)
+++ sys/kern/kern_linker.c	(working copy)
@@ -1199,7 +1199,12 @@ kldstat(struct thread *td, struct kldsta
 
 	td->td_retval[0] = 0;
 
-	return (copyout(&stat, uap->stat, sizeof(struct kld_file_stat)));
+	if (version_num == 1)
+		return (copyout(&stat, uap->stat,
+		    sizeof(struct kld_file_stat_1)));
+	else
+		return (copyout(&stat, uap->stat,
+		    sizeof(struct kld_file_stat)));
 }
 
 int
%%%

-- 
Jaakko