hush: fix potential buffer overflow on NOMMU

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

1 files changed, 6 insertions, 3 deletions

diff --git a/shell/hush.c b/shell/hush.c
index 8de8d3c2a..88a7b988a 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -2919,7 +2919,9 @@ static void re_execute_shell(char ***to_free, const char *s,
                 char *g_argv0, char **g_argv,
                 char **builtin_argv)
 {
-        char param_buf[sizeof("-$%x:%x:%x:%x:%x") + sizeof(unsigned) * 2];
+#define NOMMU_HACK_FMT ("-$%x:%x:%x:%x:%x:%llx" IF_HUSH_LOOPS(":%x"))
+        /* delims + 2 * (number of bytes in printed hex numbers) */
+        char param_buf[sizeof(NOMMU_HACK_FMT) + 2 * (sizeof(int)*6 + sizeof(long long)*1)];
         char *heredoc_argv[4];
         struct variable *cur;
 # if ENABLE_HUSH_FUNCTIONS
@@ -2953,7 +2955,7 @@ static void re_execute_shell(char ***to_free, const char *s,
                 }
         }
 
-        sprintf(param_buf, "-$%x:%x:%x:%x:%x:%llx" IF_HUSH_LOOPS(":%x")
+        sprintf(param_buf, NOMMU_HACK_FMT
                         , (unsigned) G.root_pid
                         , (unsigned) G.root_ppid
                         , (unsigned) G.last_bg_pid
@@ -2962,7 +2964,8 @@ static void re_execute_shell(char ***to_free, const char *s,
                         , empty_trap_mask
                         IF_HUSH_LOOPS(, G.depth_of_loop)
                         );
-        /* 1:hush 2:-$<pid>:<pid>:<exitcode>:<depth> <vars...> <funcs...>
+#undef NOMMU_HACK_FMT
+        /* 1:hush 2:-$<pid>:<pid>:<exitcode>:<etc...> <vars...> <funcs...>
          * 3:-c 4:<cmd> 5:<arg0> <argN...> 6:NULL
          */
         cnt += 6;