linux-kernel - [RFC PATCH v6 27/34] dyndbg: fixup protect header when deleting site

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210529200029.205306-28-jim.cromie@gmail.com>
Date:   Sat, 29 May 2021 14:00:22 -0600
From:   Jim Cromie <jim.cromie@...il.com>
To:     jbaron@...mai.com, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org
Cc:     Jim Cromie <jim.cromie@...il.com>
Subject: [RFC PATCH v6 27/34] dyndbg: fixup protect header when deleting site

fix a null-ptr-deref when .site info is deleted.

  $> echo +D > /proc/dynamic_debug/control

This protects the header.site pointer from zeroing; we need it for all
the SITE_CHK sanity checking.  Probably should protect against
toggling the static_key too (in the same function), but this smaller
change fixes the crash.

Signed-off-by: Jim Cromie <jim.cromie@...il.com>
---
 lib/dynamic_debug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 659e864837ad..f2f6f2b20d01 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -247,7 +247,7 @@ static void ddebug_alter_site(struct _ddebug *dp,
 #ifdef SITE_CHK
 	/* delete site info for this callsite */
 	if (modifiers->flags & _DPRINTK_FLAGS_DELETE_SITE) {
-		if (dp->site) {
+		if (dp->site && !is_dyndbg_header_pair(dp, dp->site)) {
 			vpr_info("dropping site info %s.%s.%d\n", dp->site->filename,
 				dp->site->function, dp->lineno);
 			dp->site = NULL;
-- 
2.31.1