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git-prompt.sh: don't put unsanitized branch names in $PS1

Both bash and zsh subject the value of PS1 to parameter expansion,
command substitution, and arithmetic expansion.  Rather than include
the raw, unescaped branch name in PS1 when running in two- or
three-argument mode, construct PS1 to reference a variable that holds
the branch name.  Because the shells do not recursively expand, this
avoids arbitrary code execution by specially-crafted branch names such
as '$(IFS=_;cmd=sudo_rm_-rf_/;$cmd)'.

Signed-off-by: Richard Hansen <rhansen@bbn.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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rhansen authored and gitster committed Apr 21, 2014
1 parent 7bbc4e8 commit 8976500cbbb13270398d3b3e07a17b8cc7bff43f
Showing with 54 additions and 24 deletions.
  1. +32 −2 contrib/completion/git-prompt.sh
  2. +22 −22 t/t9903-bash-prompt.sh
@@ -207,7 +207,18 @@ __git_ps1_show_upstream ()
p=" u+${count#* }-${count% *}" ;;
esac
if [[ -n "$count" && -n "$name" ]]; then
p="$p $(git rev-parse --abbrev-ref "$upstream" 2>/dev/null)"
__git_ps1_upstream_name=$(git rev-parse \
--abbrev-ref "$upstream" 2>/dev/null)
if [ $pcmode = yes ]; then
# see the comments around the
# __git_ps1_branch_name variable below
p="$p \${__git_ps1_upstream_name}"
else
p="$p ${__git_ps1_upstream_name}"
# not needed anymore; keep user's
# environment clean
unset __git_ps1_upstream_name
fi
fi
fi
@@ -438,8 +449,27 @@ __git_ps1 ()
__git_ps1_colorize_gitstring
fi
b=${b##refs/heads/}
if [ $pcmode = yes ]; then
# In pcmode (and only pcmode) the contents of
# $gitstring are subject to expansion by the shell.
# Avoid putting the raw ref name in the prompt to
# protect the user from arbitrary code execution via
# specially crafted ref names (e.g., a ref named
# '$(IFS=_;cmd=sudo_rm_-rf_/;$cmd)' would execute
# 'sudo rm -rf /' when the prompt is drawn). Instead,
# put the ref name in a new global variable (in the
# __git_ps1_* namespace to avoid colliding with the
# user's environment) and reference that variable from
# PS1.
__git_ps1_branch_name=$b
# note that the $ is escaped -- the variable will be
# expanded later (when it's time to draw the prompt)
b="\${__git_ps1_branch_name}"
fi
local f="$w$i$s$u"
local gitstring="$c${b##refs/heads/}${f:+$z$f}$r$p"
local gitstring="$c$b${f:+$z$f}$r$p"
if [ $pcmode = yes ]; then
if [ "${__git_printf_supports_v-}" != yes ]; then
View
@@ -452,67 +452,67 @@ test_expect_success 'prompt - format string starting with dash' '
'
test_expect_success 'prompt - pc mode' '
printf "BEFORE: (master):AFTER" >expected &&
printf "BEFORE: (\${__git_ps1_branch_name}):AFTER\\nmaster" >expected &&
printf "" >expected_output &&
(
__git_ps1 "BEFORE:" ":AFTER" >"$actual" &&
test_cmp expected_output "$actual" &&
printf "%s" "$PS1" >"$actual"
printf "%s\\n%s" "$PS1" "${__git_ps1_branch_name}" >"$actual"
) &&
test_cmp expected "$actual"
'
test_expect_success 'prompt - bash color pc mode - branch name' '
printf "BEFORE: (${c_green}master${c_clear}):AFTER" >expected &&
printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear}):AFTER\\nmaster" >expected &&
(
GIT_PS1_SHOWCOLORHINTS=y &&
__git_ps1 "BEFORE:" ":AFTER" >"$actual"
printf "%s" "$PS1" >"$actual"
printf "%s\\n%s" "$PS1" "${__git_ps1_branch_name}" >"$actual"
) &&
test_cmp expected "$actual"
'
test_expect_success 'prompt - bash color pc mode - detached head' '
printf "BEFORE: (${c_red}(%s...)${c_clear}):AFTER" $(git log -1 --format="%h" b1^) >expected &&
printf "BEFORE: (${c_red}\${__git_ps1_branch_name}${c_clear}):AFTER\\n(%s...)" $(git log -1 --format="%h" b1^) >expected &&
git checkout b1^ &&
test_when_finished "git checkout master" &&
(
GIT_PS1_SHOWCOLORHINTS=y &&
__git_ps1 "BEFORE:" ":AFTER" &&
printf "%s" "$PS1" >"$actual"
printf "%s\\n%s" "$PS1" "${__git_ps1_branch_name}" >"$actual"
) &&
test_cmp expected "$actual"
'
test_expect_success 'prompt - bash color pc mode - dirty status indicator - dirty worktree' '
printf "BEFORE: (${c_green}master${c_clear} ${c_red}*${c_clear}):AFTER" >expected &&
printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear} ${c_red}*${c_clear}):AFTER\\nmaster" >expected &&
echo "dirty" >file &&
test_when_finished "git reset --hard" &&
(
GIT_PS1_SHOWDIRTYSTATE=y &&
GIT_PS1_SHOWCOLORHINTS=y &&
__git_ps1 "BEFORE:" ":AFTER" &&
printf "%s" "$PS1" >"$actual"
printf "%s\\n%s" "$PS1" "${__git_ps1_branch_name}" >"$actual"
) &&
test_cmp expected "$actual"
'
test_expect_success 'prompt - bash color pc mode - dirty status indicator - dirty index' '
printf "BEFORE: (${c_green}master${c_clear} ${c_green}+${c_clear}):AFTER" >expected &&
printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear} ${c_green}+${c_clear}):AFTER\\nmaster" >expected &&
echo "dirty" >file &&
test_when_finished "git reset --hard" &&
git add -u &&
(
GIT_PS1_SHOWDIRTYSTATE=y &&
GIT_PS1_SHOWCOLORHINTS=y &&
__git_ps1 "BEFORE:" ":AFTER" &&
printf "%s" "$PS1" >"$actual"
printf "%s\\n%s" "$PS1" "${__git_ps1_branch_name}" >"$actual"
) &&
test_cmp expected "$actual"
'
test_expect_success 'prompt - bash color pc mode - dirty status indicator - dirty index and worktree' '
printf "BEFORE: (${c_green}master${c_clear} ${c_red}*${c_green}+${c_clear}):AFTER" >expected &&
printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear} ${c_red}*${c_green}+${c_clear}):AFTER\\nmaster" >expected &&
echo "dirty index" >file &&
test_when_finished "git reset --hard" &&
git add -u &&
@@ -521,69 +521,69 @@ test_expect_success 'prompt - bash color pc mode - dirty status indicator - dirt
GIT_PS1_SHOWCOLORHINTS=y &&
GIT_PS1_SHOWDIRTYSTATE=y &&
__git_ps1 "BEFORE:" ":AFTER" &&
printf "%s" "$PS1" >"$actual"
printf "%s\\n%s" "$PS1" "${__git_ps1_branch_name}" >"$actual"
) &&
test_cmp expected "$actual"
'
test_expect_success 'prompt - bash color pc mode - dirty status indicator - before root commit' '
printf "BEFORE: (${c_green}master${c_clear} ${c_green}#${c_clear}):AFTER" >expected &&
printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear} ${c_green}#${c_clear}):AFTER\\nmaster" >expected &&
(
GIT_PS1_SHOWDIRTYSTATE=y &&
GIT_PS1_SHOWCOLORHINTS=y &&
cd otherrepo &&
__git_ps1 "BEFORE:" ":AFTER" &&
printf "%s" "$PS1" >"$actual"
printf "%s\\n%s" "$PS1" "${__git_ps1_branch_name}" >"$actual"
) &&
test_cmp expected "$actual"
'
test_expect_success 'prompt - bash color pc mode - inside .git directory' '
printf "BEFORE: (${c_green}GIT_DIR!${c_clear}):AFTER" >expected &&
printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear}):AFTER\\nGIT_DIR!" >expected &&
echo "dirty" >file &&
test_when_finished "git reset --hard" &&
(
GIT_PS1_SHOWDIRTYSTATE=y &&
GIT_PS1_SHOWCOLORHINTS=y &&
cd .git &&
__git_ps1 "BEFORE:" ":AFTER" &&
printf "%s" "$PS1" >"$actual"
printf "%s\\n%s" "$PS1" "${__git_ps1_branch_name}" >"$actual"
) &&
test_cmp expected "$actual"
'
test_expect_success 'prompt - bash color pc mode - stash status indicator' '
printf "BEFORE: (${c_green}master${c_clear} ${c_lblue}\$${c_clear}):AFTER" >expected &&
printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear} ${c_lblue}\$${c_clear}):AFTER\\nmaster" >expected &&
echo 2 >file &&
git stash &&
test_when_finished "git stash drop" &&
(
GIT_PS1_SHOWSTASHSTATE=y &&
GIT_PS1_SHOWCOLORHINTS=y &&
__git_ps1 "BEFORE:" ":AFTER" &&
printf "%s" "$PS1" >"$actual"
printf "%s\\n%s" "$PS1" "${__git_ps1_branch_name}" >"$actual"
) &&
test_cmp expected "$actual"
'
test_expect_success 'prompt - bash color pc mode - untracked files status indicator' '
printf "BEFORE: (${c_green}master${c_clear} ${c_red}%%${c_clear}):AFTER" >expected &&
printf "BEFORE: (${c_green}\${__git_ps1_branch_name}${c_clear} ${c_red}%%${c_clear}):AFTER\\nmaster" >expected &&
(
GIT_PS1_SHOWUNTRACKEDFILES=y &&
GIT_PS1_SHOWCOLORHINTS=y &&
__git_ps1 "BEFORE:" ":AFTER" &&
printf "%s" "$PS1" >"$actual"
printf "%s\\n%s" "$PS1" "${__git_ps1_branch_name}" >"$actual"
) &&
test_cmp expected "$actual"
'
test_expect_success 'prompt - zsh color pc mode' '
printf "BEFORE: (%%F{green}master%%f):AFTER" >expected &&
printf "BEFORE: (%%F{green}\${__git_ps1_branch_name}%%f):AFTER\\nmaster" >expected &&
(
ZSH_VERSION=5.0.0 &&
GIT_PS1_SHOWCOLORHINTS=y &&
__git_ps1 "BEFORE:" ":AFTER" >"$actual"
printf "%s" "$PS1" >"$actual"
printf "%s\\n%s" "$PS1" "${__git_ps1_branch_name}" >"$actual"
) &&
test_cmp expected "$actual"
'

1 comment on commit 8976500

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carnil commented on 8976500 Mar 20, 2017

This is CVE-2014-9938

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