66 lines
2.4 KiB
Diff
66 lines
2.4 KiB
Diff
|
From c5d2964d498da0ac06799e5f040de74a0f5d2deb Mon Sep 17 00:00:00 2001
|
||
|
|
From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
|
||
|
|
Date: Wed, 23 Jun 2021 11:46:41 +0200
|
||
|
|
Subject: [PATCH] basic/unit-name: do not use strdupa() on a path
|
||
|
|
|
||
|
|
The path may have unbounded length, for example through a fuse mount.
|
||
|
|
|
||
|
|
CVE-2021-33910: attacked controlled alloca() leads to crash in systemd and
|
||
|
|
ultimately a kernel panic. Systemd parses the content of /proc/self/mountinfo
|
||
|
|
and each mountpoint is passed to mount_setup_unit(), which calls
|
||
|
|
unit_name_path_escape() underneath. A local attacker who is able to mount a
|
||
|
|
filesystem with a very long path can crash systemd and the whole system.
|
||
|
|
|
||
|
|
https://bugzilla.redhat.com/show_bug.cgi?id=1970887
|
||
|
|
|
||
|
|
The resulting string length is bounded by UNIT_NAME_MAX, which is 256. But we
|
||
|
|
can't easily check the length after simplification before doing the
|
||
|
|
simplification, which in turns uses a copy of the string we can write to.
|
||
|
|
So we can't reject paths that are too long before doing the duplication.
|
||
|
|
Hence the most obvious solution is to switch back to strdup(), as before
|
||
|
|
7410616cd9dbbec97cf98d75324da5cda2b2f7a2.
|
||
|
|
|
||
|
|
Resolves: #1974700
|
||
|
|
|
||
|
|
(cherry picked from commit 441e0115646d54f080e5c3bb0ba477c892861ab9)
|
||
|
|
---
|
||
|
|
src/basic/unit-name.c | 13 +++++--------
|
||
|
|
1 file changed, 5 insertions(+), 8 deletions(-)
|
||
|
|
|
||
|
|
diff --git a/src/basic/unit-name.c b/src/basic/unit-name.c
|
||
|
|
index 1b81fe268f..614eb8649b 100644
|
||
|
|
--- a/src/basic/unit-name.c
|
||
|
|
+++ b/src/basic/unit-name.c
|
||
|
|
@@ -369,12 +369,13 @@ int unit_name_unescape(const char *f, char **ret) {
|
||
|
|
}
|
||
|
|
|
||
|
|
int unit_name_path_escape(const char *f, char **ret) {
|
||
|
|
- char *p, *s;
|
||
|
|
+ _cleanup_free_ char *p = NULL;
|
||
|
|
+ char *s;
|
||
|
|
|
||
|
|
assert(f);
|
||
|
|
assert(ret);
|
||
|
|
|
||
|
|
- p = strdupa(f);
|
||
|
|
+ p = strdup(f);
|
||
|
|
if (!p)
|
||
|
|
return -ENOMEM;
|
||
|
|
|
||
|
|
@@ -386,13 +387,9 @@ int unit_name_path_escape(const char *f, char **ret) {
|
||
|
|
if (!path_is_normalized(p))
|
||
|
|
return -EINVAL;
|
||
|
|
|
||
|
|
- /* Truncate trailing slashes */
|
||
|
|
+ /* Truncate trailing slashes and skip leading slashes */
|
||
|
|
delete_trailing_chars(p, "/");
|
||
|
|
-
|
||
|
|
- /* Truncate leading slashes */
|
||
|
|
- p = skip_leading_chars(p, "/");
|
||
|
|
-
|
||
|
|
- s = unit_name_escape(p);
|
||
|
|
+ s = unit_name_escape(skip_leading_chars(p, "/"));
|
||
|
|
}
|
||
|
|
if (!s)
|
||
|
|
return -ENOMEM;
|