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scm/git: prevent exec bomb with 'env :userpaths'

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Using `git` from `Formula#install` can cause an exec bomb if used in a
formula with `env :userpaths` because that causes both `Library/ENV/4.3`
and `Library/ENV/scm` to be in PATH, both of which contain a `git`
binary that is the same SCM wrapper. Those will mutually exec each other
indefinitely as they fail to detect that they are the same wrapper.

Extend the exec-bomb protection to check the paths after all symbolic
links have been expanded to prevent this situation.

Fixes #43.
Fixes Homebrew/homebrew-core#133.
Fixed Homebrew/homebrew-core#143.

Closes #46.

Signed-off-by: Martin Afanasjew <martin@afanasjew.de>
This commit is contained in:
Martin Afanasjew 2016-04-07 22:09:14 +02:00
parent d5085edce0
commit d7aa0c0335
1 changed files with 4 additions and 1 deletions
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5
Library/ENV/scm/git
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@ -13,13 +13,16 @@ exec "$HOMEBREW_RUBY_PATH" -x "$0" "$@"
# This script because we support $GIT, $HOMEBREW_SVN, etc., Xcode-only and # This script because we support $GIT, $HOMEBREW_SVN, etc., Xcode-only and
# no Xcode/CLT configurations. Order is careful to be what the user would want. # no Xcode/CLT configurations. Order is careful to be what the user would want.
require "pathname"
SELF_REAL = Pathname.new(__FILE__).realpath
F = File.basename(__FILE__).freeze F = File.basename(__FILE__).freeze
D = File.expand_path(File.dirname(__FILE__)).freeze D = File.expand_path(File.dirname(__FILE__)).freeze
def exec(*args) def exec(*args)
# prevent fork-bombs # prevent fork-bombs
arg0 = args.first arg0 = args.first
return if arg0 =~ /^#{F}/i || File.expand_path(arg0) == File.expand_path(__FILE__) return if arg0 =~ /^#{F}/i || Pathname.new(arg0).realpath == SELF_REAL
super super
end end