gzip: security fixes

Fixes #536998

pkgs/tools/compression/gzip/CVE-2026-41991.patch

@@ -0,0 +1,52 @@
+From 4e6f8b24ab823146ab8776f0b7fe486ab34d4269 Mon Sep 17 00:00:00 2001
+From: Paul Eggert <eggert@cs.ucla.edu>
+Date: Thu, 16 Apr 2026 12:11:44 -0700
+Subject: gzexe: use -C if lacking mktemp
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+(Problem reported by Michał Majchrowicz.)
+* gzexe.in: If mktemp is needed but not installed,
+use ‘set -C’ to avoid a race when creating a temporary file.
+* zdiff.in: Use the same pattern here, even though the old
+code was probably OK anyway.
+---
+ gzexe.in | 1 +
+ zdiff.in | 7 +++----
+ 2 files changed, 4 insertions(+), 4 deletions(-)
+
+diff --git a/gzexe.in b/gzexe.in
+index ea4ef94..f3d46cc 100644
+--- a/gzexe.in
++++ b/gzexe.in
+@@ -127,6 +127,7 @@ for i do
+     tmp=`mktemp "${dir}gzexeXXXXXXXXX"`
+   else
+     tmp=${dir}gzexe$$
++    (umask 77; set -C; > "$tmp")
+   fi && { cp -p "$file" "$tmp" 2>/dev/null || cp "$file" "$tmp"; } || {
+     res=$?
+     printf >&2 '%s\n' "$0: cannot copy $file"
+diff --git a/zdiff.in b/zdiff.in
+index 289e466..53266df 100644
+--- a/zdiff.in
++++ b/zdiff.in
+@@ -156,12 +156,11 @@ case $file2 in
+                           *) TMPDIR=/tmp/;;
+                         esac
+                         if command -v mktemp >/dev/null 2>&1; then
+-                          tmp=`mktemp "${TMPDIR}zdiffXXXXXXXXX"` ||
+-                            exit 2
++                          tmp=`mktemp "${TMPDIR}zdiffXXXXXXXXX"`
+                         else
+-                          set -C
+                           tmp=${TMPDIR}zdiff$$
+-                        fi
++                          (umask 77; set -C; > "$tmp")
++                        fi &&
+                         'gzip' -cdfq -- "$file2" > "$tmp" || exit 2
+                         gzip_status=$(
+                           exec 4>&1
+-- 
+cgit v1.2.3

pkgs/tools/compression/gzip/CVE-2026-41992.patch

@@ -0,0 +1,35 @@
+From 63dbf6b3b9e6e781df1a6a64e609b10e23969681 Mon Sep 17 00:00:00 2001
+From: Paul Eggert <eggert@cs.ucla.edu>
+Date: Wed, 15 Apr 2026 12:00:17 -0700
+Subject: gzip: don’t mishandle .lzh after .Z
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Problem reported by Michał Majchrowicz.
+* unlzh.c (read_c_len): Clear left and right when n == 0.
+---
+ unlzh.c | 6 ++++++
+ 1 file changed, 6 insertions(+)
+
+(limited to 'unlzh.c')
+
+diff --git a/unlzh.c b/unlzh.c
+index 3320196..a6cf109 100644
+--- a/unlzh.c
++++ b/unlzh.c
+@@ -232,6 +232,12 @@ read_c_len ()
+         c = getbits(CBIT);
+         for (i = 0; i < NC; i++) c_len[i] = 0;
+         for (i = 0; i < 4096; i++) c_table[i] = c;
++
++        /* Needed in case LEFT and RIGHT are reused from a previous
++           LZW decompression.  It may be overkill to clear all of both
++           arrays, but nobody has had time to analyze this carefully.  */
++        memzero(left, (2 * NC - 1) * sizeof *left);
++        memzero(right, (2 * NC - 1) * sizeof *left);
+     } else {
+         i = 0;
+         while (i < n) {
+-- 
+cgit v1.3

pkgs/tools/compression/gzip/default.nix

@@ -25,6 +25,11 @@ stdenv.mkDerivation (finalAttrs: {
     hash = "sha256-Aae4gb0iC/32Ffl7hxj4C9/T9q3ThbmT3Pbv0U6MCsY=";
   };
 
+  patches = [
+    ./CVE-2026-41991.patch
+    ./CVE-2026-41992.patch
+  ];
+
   outputs = [
     "out"
     "man"