hush: protect against self-modifying trap code

function                                             old     new   delta
check_and_run_traps                                  211     236     +25

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/shell/hush.c b/shell/hush.c
index ddf377355..585c51bd5 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -2004,10 +2004,12 @@ static int check_and_run_traps(void)
                                 smalluint save_rcode;
                                 char *argv[3];
                                 /* argv[0] is unused */
-                                argv[1] = G_traps[sig];
+                                argv[1] = xstrdup(G_traps[sig]);
+                                /* why strdup? trap can modify itself: trap 'trap "echo oops" INT' INT */
                                 argv[2] = NULL;
                                 save_rcode = G.last_exitcode;
                                 builtin_eval(argv);
+                                free(argv[1]);
 //FIXME: shouldn't it be set to 128 + sig instead?
                                 G.last_exitcode = save_rcode;
                                 last_sig = sig;