From 02e0f94fff27cad2ba4e65bdc4b21146b3bd9a97 Mon Sep 17 00:00:00 2001
From: Oliver Kiddle <opk@zsh.org>
Date: Wed, 15 Dec 2021 01:56:40 +0100
Subject: [PATCH 1/2] security/41: Don't perform PROMPT_SUBST evaluation on
%F/%K arguments
Mitigates CVE-2021-45444
Upstream-commit: c187154f47697cdbf822c2f9d714d570ed4a0fd1
Signed-off-by: Kamil Dudka <kdudka@redhat.com>
---
Src/prompt.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/Src/prompt.c b/Src/prompt.c
index b65bfb8..91e21c8 100644
--- a/Src/prompt.c
+++ b/Src/prompt.c
@@ -244,6 +244,12 @@ parsecolorchar(zattr arg, int is_fg)
bv->fm += 2; /* skip over F{ */
if ((ep = strchr(bv->fm, '}'))) {
char oc = *ep, *col, *coll;
+ int ops = opts[PROMPTSUBST], opb = opts[PROMPTBANG];
+ int opp = opts[PROMPTPERCENT];
+
+ opts[PROMPTPERCENT] = 1;
+ opts[PROMPTSUBST] = opts[PROMPTBANG] = 0;
+
*ep = '\0';
/* expand the contents of the argument so you can use
* %v for example */
@@ -252,6 +258,10 @@ parsecolorchar(zattr arg, int is_fg)
arg = match_colour((const char **)&coll, is_fg, 0);
free(col);
bv->fm = ep;
+
+ opts[PROMPTSUBST] = ops;
+ opts[PROMPTBANG] = opb;
+ opts[PROMPTPERCENT] = opp;
} else {
arg = match_colour((const char **)&bv->fm, is_fg, 0);
if (*bv->fm != '}')
--
2.34.1
From 6102afb5dfd7c704f9cf99bedb9c3ec3c7dbe8e3 Mon Sep 17 00:00:00 2001
From: dana <dana@dana.is>
Date: Tue, 21 Dec 2021 13:13:33 -0600
Subject: [PATCH 2/2] CVE-2021-45444: Update NEWS/README
Upstream-commit: bdc4d70a7e033b754e68a8659a037ea0fc5f38de
Signed-off-by: Kamil Dudka <kdudka@redhat.com>
---
NEWS | 20 ++++++++++++++++++++
README | 6 ++++++
2 files changed, 26 insertions(+)
diff --git a/NEWS b/NEWS
index 964e163..327b449 100644
--- a/NEWS
+++ b/NEWS
@@ -4,6 +4,26 @@ CHANGES FROM PREVIOUS VERSIONS OF ZSH
Note also the list of incompatibilities in the README file.
+Changes since 5.8
+-----------------
+
+CVE-2021-45444: Some prompt expansion sequences, such as %F, support
+'arguments' which are themselves expanded in case they contain colour
+values, etc. This additional expansion would trigger PROMPT_SUBST
+evaluation, if enabled. This could be abused to execute code the user
+didn't expect. e.g., given a certain prompt configuration, an attacker
+could trick a user into executing arbitrary code by having them check
+out a Git branch with a specially crafted name.
+
+This is fixed in the shell itself by no longer performing PROMPT_SUBST
+evaluation on these prompt-expansion arguments.
+
+Users who are concerned about an exploit but unable to update their
+binaries may apply the partial work-around described in the file
+Etc/CVE-2021-45444-VCS_Info-workaround.patch included with the shell
+source. [ Reported by RyotaK <security@ryotak.me>. Additional thanks to
+Marc Cornellà <hello@mcornella.com>. ]
+
Changes since 5.7.1-test-3
--------------------------
diff --git a/README b/README
index 7f1dd5f..c9e994a 100644
--- a/README
+++ b/README
@@ -31,6 +31,12 @@ Zsh is a shell with lots of features. For a list of some of these, see the
file FEATURES, and for the latest changes see NEWS. For more
details, see the documentation.
+Incompatibilities since 5.8
+---------------------------
+
+PROMPT_SUBST expansion is no longer performed on arguments to prompt-
+expansion sequences such as %F.
+
Incompatibilities since 5.7.1
-----------------------------
--
2.34.1