fix: escape % characters in git prompts

This patch adds missing % character escaping for custom git prompts
used in a few themes. It also includes escaping for git-prompt.sh.

In combination with CVE-2021-45444, this could allow code execution
when displaying branch information in cloned malicious git repositories.
However, zsh 5.8.1 and newer are largely the default zsh versions, and
on those supported distributions with older zsh versions, the CVE has been
found to be also patched.

For this reason, this doesn't qualify as a security patch, but a
bug fix for proper printing of git branches.

plugins/gitfast/git-prompt.sh

@@ -235,7 +235,7 @@ __git_ps1_show_upstream ()
 			if [ $pcmode = yes ] && [ $ps1_expanded = yes ]; then
 				upstream="$upstream \${__git_ps1_upstream_name}"
 			else
-				upstream="$upstream ${__git_ps1_upstream_name}"
+				upstream="$upstream ${__git_ps1_upstream_name//\%/%%}"
 				# not needed anymore; keep user's
 				# environment clean
 				unset __git_ps1_upstream_name
@@ -570,6 +570,9 @@ __git_ps1 ()
 	if [ $pcmode = yes ] && [ $ps1_expanded = yes ]; then
 		__git_ps1_branch_name=$b
 		b="\${__git_ps1_branch_name}"
+	else
+		# escape % in branch name to avoid prompt expansion issues
+		b="${b//\%/%%}"
 	fi
 
 	if [ -n "${GIT_PS1_SHOWCOLORHINTS-}" ]; then

themes/eastwood.zsh-theme

@@ -16,7 +16,8 @@ ZSH_THEME_GIT_PROMPT_CLEAN=""
 git_custom_status() {
   local cb=$(git_current_branch)
   if [ -n "$cb" ]; then
-    echo "$(parse_git_dirty)$ZSH_THEME_GIT_PROMPT_PREFIX$(git_current_branch)$ZSH_THEME_GIT_PROMPT_SUFFIX"
+    cb="${cb//\%/%%}"
+    echo "$(parse_git_dirty)$ZSH_THEME_GIT_PROMPT_PREFIX${cb}$ZSH_THEME_GIT_PROMPT_SUFFIX"
   fi
 }
 

themes/gallois.zsh-theme

@@ -10,6 +10,7 @@ ZSH_THEME_GIT_PROMPT_CLEAN=""
 git_custom_status() {
   local branch=$(git_current_branch)
   [[ -n "$branch" ]] || return 0
+  branch="${branch//\%/%%}"
   print "%{${fg_bold[yellow]}%}$(work_in_progress)%{$reset_color%}\
 ${ZSH_THEME_GIT_PROMPT_PREFIX}$(parse_git_dirty)${branch}\
 ${ZSH_THEME_GIT_PROMPT_SUFFIX}"

themes/josh.zsh-theme

@@ -31,7 +31,7 @@ function josh_prompt {
     prompt=" $prompt"
   done
 
-  prompt="%{%F{green}%}$PWD$prompt%{%F{red}%}$(ruby_prompt_info)%{$reset_color%} $(git_current_branch)"
+  prompt="%{%F{green}%}$PWD$prompt%{%F{red}%}$(ruby_prompt_info)%{$reset_color%} ${branch//\%/%%}"
 
   echo $prompt
 }

themes/juanghurtado.zsh-theme

@@ -41,4 +41,4 @@ USER_COLOR=$GREEN_BOLD
 PROMPT='
 %{$USER_COLOR%}%n@%m%{$WHITE%}:%{$YELLOW%}%~%u$(parse_git_dirty)$(git_prompt_ahead)%{$RESET_COLOR%}
 %{$BLUE%}>%{$RESET_COLOR%} '
-RPROMPT='%{$GREEN_BOLD%}$(git_current_branch)$(git_prompt_short_sha)$(git_prompt_status)%{$RESET_COLOR%}'
+RPROMPT='%{$GREEN_BOLD%}${$(git_current_branch)//\%/%%}$(git_prompt_short_sha)$(git_prompt_status)%{$RESET_COLOR%}'

themes/lukerandall.zsh-theme

@@ -7,7 +7,7 @@ function my_git_prompt_info() {
   ref=$(git symbolic-ref HEAD 2> /dev/null) || return
   GIT_STATUS=$(git_prompt_status)
   [[ -n $GIT_STATUS ]] && GIT_STATUS=" $GIT_STATUS"
-  echo "$ZSH_THEME_GIT_PROMPT_PREFIX${ref#refs/heads/}$GIT_STATUS$ZSH_THEME_GIT_PROMPT_SUFFIX"
+  echo "$ZSH_THEME_GIT_PROMPT_PREFIX${${ref#refs/heads/}//\%/%%}$GIT_STATUS$ZSH_THEME_GIT_PROMPT_SUFFIX"
 }
 
 PROMPT='%{$fg_bold[green]%}%n@%m%{$reset_color%} %{$fg_bold[blue]%}%2~%{$reset_color%} $(my_git_prompt_info)%{$reset_color%}%B»%b '

themes/mortalscumbag.zsh-theme

@@ -42,7 +42,9 @@ function my_git_prompt() {
 }
 
 function my_current_branch() {
-  echo $(git_current_branch || echo "(no branch)")
+  local branch
+  branch=$(git_current_branch || echo "(no branch)")
+  echo "${branch//\%/%%}"
 }
 
 function ssh_connection() {

themes/oldgallois.zsh-theme

@@ -10,6 +10,7 @@ ZSH_THEME_GIT_PROMPT_CLEAN=""
 git_custom_status() {
   local branch=$(git_current_branch)
   [[ -n "$branch" ]] || return 0
+  branch="${branch//\%/%%}"
   echo "$(parse_git_dirty)\
 %{${fg_bold[yellow]}%}$(work_in_progress)%{$reset_color%}\
 ${ZSH_THEME_GIT_PROMPT_PREFIX}${branch}${ZSH_THEME_GIT_PROMPT_SUFFIX}"

themes/peepcode.zsh-theme

@@ -31,7 +31,7 @@ git_prompt() {
   local cb=$(git_current_branch)
   if [[ -n "$cb" ]]; then
     local repo_path=$(git_repo_path)
-    echo " %{$fg_bold[grey]%}$cb %{$fg[white]%}$(git_commit_id)%{$reset_color%}$(git_mode)$(git_dirty)"
+    echo " %{$fg_bold[grey]%}${cb//\%/%%} %{$fg[white]%}$(git_commit_id)%{$reset_color%}$(git_mode)$(git_dirty)"
   fi
 }
 

themes/rkj-repos.zsh-theme

@@ -23,7 +23,8 @@ function mygit() {
   if [[ "$(git config --get oh-my-zsh.hide-status)" != "1" ]]; then
     ref=$(command git symbolic-ref HEAD 2> /dev/null) || \
     ref=$(command git rev-parse --short HEAD 2> /dev/null) || return
-    echo "$ZSH_THEME_GIT_PROMPT_PREFIX${ref#refs/heads/}$(git_prompt_short_sha)$(git_prompt_status)%{$fg_bold[blue]%}$ZSH_THEME_GIT_PROMPT_SUFFIX "
+    ref=${${ref#refs/heads/}//\%/%%}
+    echo "${ZSH_THEME_GIT_PROMPT_PREFIX}${ref}$(git_prompt_short_sha)$(git_prompt_status)%{$fg_bold[blue]%}${ZSH_THEME_GIT_PROMPT_SUFFIX} "
   fi
 }
 

themes/sunrise.zsh-theme

@@ -62,7 +62,7 @@ custom_git_prompt_status() {
 # get the name of the branch we are on (copied and modified from git.zsh)
 function custom_git_prompt() {
   ref=$(git symbolic-ref HEAD 2> /dev/null) || return
-  echo "$ZSH_THEME_GIT_PROMPT_PREFIX${ref#refs/heads/}$(parse_git_dirty)$(git_prompt_ahead)$(custom_git_prompt_status)$ZSH_THEME_GIT_PROMPT_SUFFIX"
+  echo "$ZSH_THEME_GIT_PROMPT_PREFIX${${ref#refs/heads/}//\%/%%}$(parse_git_dirty)$(git_prompt_ahead)$(custom_git_prompt_status)$ZSH_THEME_GIT_PROMPT_SUFFIX"
 }
 
 # %B sets bold text