svn commit: r352245 - head/sys/kern

[Kyle Evans]

Author: kevans
Date: Thu Sep 12 14:34:46 2019
New Revision: 352245
URL: https://svnweb.freebsd.org/changeset/base/352245

Log:
  Follow up r352244: kenv: tighten up assertions
  
  As I like to forget: static kenv var formatting is actually such that an
  empty environment would be double null bytes. We should make sure that a
  non-zero buffer has at least enough for this, though most of the current
  usage is with a 4k buffer.

Modified:
  head/sys/kern/kern_environment.c

Modified: head/sys/kern/kern_environment.c
==============================================================================
--- head/sys/kern/kern_environment.c	Thu Sep 12 13:51:43 2019	(r352244)
+++ head/sys/kern/kern_environment.c	Thu Sep 12 14:34:46 2019	(r352245)
@@ -250,7 +250,15 @@ init_static_kenv(char *buf, size_t len)
 	char *eval;
 
 	KASSERT(!dynamic_kenv, ("kenv: dynamic_kenv already initialized"));
-	KASSERT(len == 0 || *buf == '\0',
+	/*
+	 * Suitably sized means it must be able to hold at least one empty
+	 * variable, otherwise things go belly up if a kern_getenv call is
+	 * made without a prior call to kern_setenv as we have a malformed
+	 * environment.
+	 */
+	KASSERT(len == 0 || len >= 2,
+	    ("kenv: static env must be initialized or suitably sized"));
+	KASSERT(len == 0 || (*buf == '\0' && *(buf + 1) == '\0'),
 	    ("kenv: sized buffer must be initially empty"));
 
 	/*