Control: tags 1009167 + patch
Control: tags 1009167 + pending
Dear maintainer,
I've prepared an NMU for xz-utils (versioned as 5.2.5-2.1) and
uploaded it to DELAYED/2. Please feel free to tell me if I
should delay it longer.
Regards,
Salvatore
diff -Nru xz-utils-5.2.5/debian/changelog xz-utils-5.2.5/debian/changelog
--- xz-utils-5.2.5/debian/changelog 2021-03-08 23:01:54.0 +0100
+++ xz-utils-5.2.5/debian/changelog 2022-04-10 13:31:29.0 +0200
@@ -1,3 +1,11 @@
+xz-utils (5.2.5-2.1) unstable; urgency=medium
+
+ * Non-maintainer upload.
+ * xzgrep: Fix escaping of malicious filenames (ZDI-CAN-16587)
+(CVE-2022-1271) (Closes: #1009167)
+
+ -- Salvatore Bonaccorso Sun, 10 Apr 2022 13:31:29 +0200
+
xz-utils (5.2.5-2) unstable; urgency=medium
* Non-maintainer upload (Closes: #983067).
diff -Nru xz-utils-5.2.5/debian/patches/0010-xzgrep-Fix-escaping-of-malicious-filenames-ZDI-CAN-1.patch xz-utils-5.2.5/debian/patches/0010-xzgrep-Fix-escaping-of-malicious-filenames-ZDI-CAN-1.patch
--- xz-utils-5.2.5/debian/patches/0010-xzgrep-Fix-escaping-of-malicious-filenames-ZDI-CAN-1.patch 1970-01-01 01:00:00.0 +0100
+++ xz-utils-5.2.5/debian/patches/0010-xzgrep-Fix-escaping-of-malicious-filenames-ZDI-CAN-1.patch 2022-04-10 13:30:30.0 +0200
@@ -0,0 +1,96 @@
+From: Lasse Collin
+Date: Tue, 29 Mar 2022 19:19:12 +0300
+Subject: xzgrep: Fix escaping of malicious filenames (ZDI-CAN-16587).
+Origin: https://git.tukaani.org/?p=xz.git;a=commit;h=69d1b3fc29677af8ade8dc15dba83f0589cb63d6
+Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2022-1271
+Bug-Debian: https://bugs.debian.org/1009167
+
+Malicious filenames can make xzgrep to write to arbitrary files
+or (with a GNU sed extension) lead to arbitrary code execution.
+
+xzgrep from XZ Utils versions up to and including 5.2.5 are
+affected. 5.3.1alpha and 5.3.2alpha are affected as well.
+This patch works for all of them.
+
+This bug was inherited from gzip's zgrep. gzip 1.12 includes
+a fix for zgrep.
+
+The issue with the old sed script is that with multiple newlines,
+the N-command will read the second line of input, then the
+s-commands will be skipped because it's not the end of the
+file yet, then a new sed cycle starts and the pattern space
+is printed and emptied. So only the last line or two get escaped.
+
+One way to fix this would be to read all lines into the pattern
+space first. However, the included fix is even simpler: All lines
+except the last line get a backslash appended at the end. To ensure
+that shell command substitution doesn't eat a possible trailing
+newline, a colon is appended to the filename before escaping.
+The colon is later used to separate the filename from the grep
+output so it is fine to add it here instead of a few lines later.
+
+The old code also wasn't POSIX compliant as it used \n in the
+replacement section of the s-command. Using \ is the
+POSIX compatible method.
+
+LC_ALL=C was added to the two critical sed commands. POSIX sed
+manual recommends it when using sed to manipulate pathnames
+because in other locales invalid multibyte sequences might
+cause issues with some sed implementations. In case of GNU sed,
+these particular sed scripts wouldn't have such problems but some
+other scripts could have, see:
+
+info '(sed)Locale Considerations'
+
+This vulnerability was discovered by:
+cleemy desu wayo working with Trend Micro Zero Day Initiative
+
+Thanks to Jim Meyering and Paul Eggert discussing the different
+ways to fix this and for coordinating the patch release schedule
+with gzip.
+---
+ src/scripts/xzgrep.in | 20
+ 1 file changed, 12 insertions(+), 8 deletions(-)
+
+diff --git a/src/scripts/xzgrep.in b/src/scripts/xzgrep.in
+index b180936c808c..e5186baf84e9 100644
+--- a/src/scripts/xzgrep.in
b/src/scripts/xzgrep.in
+@@ -180,22 +180,26 @@ for i; do
+ { test $# -eq 1 || test $no_filename -eq 1; }; then
+ eval "$grep"
+ else
++ # Append a colon so that the last character will never be a newline
++ # which would otherwise get lost in shell command substitution.
++ i="$i:"
++
++ # Escape & \ | and newlines only if such characters are present
++ # (speed optimization).
+ case $i in
+ (*'
+ '* | *'&'* | *'\'* | *'|'*)
+-i=$(printf '%s\n' "$i" |
+-sed '
+- $!N
+- $s/[&\|]/\\&/g
+- $s/\n/\\n/g
+-');;
++i=$(printf '%s\n' "$i" | LC_ALL=C sed 's/[&\|]/\\&/g; $!s/$/\\/');;
+ esac
+- sed_script="s|^|$i:|"
++
++ # $i already ends with a colon so don't add it here.
++ sed_script="s|^|$i|"
+
+ # Fail if grep or sed fails.
+ r=$(
+ exec 4>&1
+-(eval "$grep" 4>&-; echo $? >&4) 3>&- | sed "$sed_script" >&3 4>&-
++(eval "$grep" 4>&-; echo $? >&4) 3>&- |
++LC_ALL=C sed "$sed_script" >&3 4>&-
+ ) || r=2
+ exit $r
+ fi >&3 5>&-
+--
