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db2a9b683

Denis Vlasenko
Denis Vlasenko
2009-04-03
FAILED Duration: 34s

Subject

hush: finally make `cmd` safe on NOMMU

Binary

No binary (build failed)

Architecture & Compiler Flags

Architecture: x86_64-linux-gnu Compiler: gcc (Ubuntu 11.4.0-1ubuntu1~22.04.3) 11.4.0

—

Build Log

(log yok)

Commit Diff GitHub →

shell/hush.c +40 -58shell/hush_test/hush-misc/syntax_err.right +2 -0
shell/hush.c+40 -58
@@ -90,14 +90,6 @@
#define SKIP_FEATURE_SH_STANDALONE(...) __VA_ARGS__
#endif
-#if !BB_MMU && ENABLE_HUSH_TICK
-//#undef ENABLE_HUSH_TICK
-//#define ENABLE_HUSH_TICK 0
-#warning On NOMMU, hush command substitution is dangerous.
-#warning Dont use it for commands which produce lots of output.
-#warning For more info see shell/hush.c, generate_stream_from_list().
-#endif
-
#if !ENABLE_HUSH_INTERACTIVE
#undef ENABLE_FEATURE_EDITING
#define ENABLE_FEATURE_EDITING 0
@@ -1649,7 +1641,7 @@ static char **o_finalize_list(o_string *o, int n)
/* Expansion can recurse */
#if ENABLE_HUSH_TICK
-static int process_command_subs(o_string *dest, struct in_str *input);
+static int process_command_subs(o_string *dest, const char *s);
#endif
static char *expand_string_to_string(const char *str);
static int parse_stream_dquoted(o_string *dest, struct in_str *input, int dquote_end);
@@ -1798,18 +1790,15 @@ static int expand_vars_to_list(o_string *output, int n, char *arg, char or_mask)
ored_ch = 0x80;
break;
#if ENABLE_HUSH_TICK
- case '`': { /* <SPECIAL_VAR_SYMBOL>`cmd<SPECIAL_VAR_SYMBOL> */
- struct in_str input;
+ case '`': /* <SPECIAL_VAR_SYMBOL>`cmd<SPECIAL_VAR_SYMBOL> */
*p = '\0';
arg++;
//TODO: can we just stuff it into "output" directly?
debug_printf_subst("SUBST '%s' first_ch %x\n", arg, first_ch);
- setup_string_in_str(&input, arg);
- process_command_subs(&subst_result, &input);
+ process_command_subs(&subst_result, arg);
debug_printf_subst("SUBST RES '%s'\n", subst_result.data);
val = subst_result.data;
goto store_val;
- }
#endif
#if ENABLE_SH_MATH_SUPPORT
case '+': { /* <SPECIAL_VAR_SYMBOL>+cmd<SPECIAL_VAR_SYMBOL> */
@@ -3711,35 +3700,20 @@ static int redirect_opt_num(o_string *o)
}
static struct pipe *parse_stream(struct in_str *input, int end_trigger);
+static void parse_and_run_string(const char *s);
#if ENABLE_HUSH_TICK
-static FILE *generate_stream_from_list(struct pipe *head)
+static FILE *generate_stream_from_string(const char *s)
{
FILE *pf;
int pid, channel[2];
xpipe(channel);
-/* *** NOMMU WARNING *** */
-/* By using vfork here, we suspend parent till child exits or execs.
- * If child will not do it before it fills the pipe, it can block forever
- * in write(STDOUT_FILENO), and parent (shell) will be also stuck.
- * Try this script:
- * yes "0123456789012345678901234567890" | dd bs=32 count=64k >TESTFILE
- * huge=`cat TESTFILE` # will block here forever
- * echo OK
- */
pid = BB_MMU ? fork() : vfork();
if (pid < 0)
bb_perror_msg_and_die(BB_MMU ? "fork" : "vfork");
+
if (pid == 0) { /* child */
- if (ENABLE_HUSH_JOB)
- die_sleep = 0; /* let nofork's xfuncs die */
- close(channel[0]); /* NB: close _first_, then move fd! */
- xmove_fd(channel[1], 1);
- /* Prevent it from trying to handle ctrl-z etc */
-#if ENABLE_HUSH_JOB
- G.run_list_level = 1;
-#endif
/* Process substitution is not considered to be usual
* 'command execution'.
* SUSv3 says ctrl-Z should be ignored, ctrl-C should not.
@@ -3749,40 +3723,47 @@ static FILE *generate_stream_from_list(struct pipe *head)
+ (1 << SIGTTIN)
+ (1 << SIGTTOU)
, SIG_IGN);
-
- /* Note: freeing 'head' here would break NOMMU. */
- _exit(run_list(head));
+ if (ENABLE_HUSH_JOB)
+ die_sleep = 0; /* let nofork's xfuncs die */
+ close(channel[0]); /* NB: close _first_, then move fd! */
+ xmove_fd(channel[1], 1);
+ /* Prevent it from trying to handle ctrl-z etc */
+ USE_HUSH_JOB(G.run_list_level = 1;)
+#if BB_MMU
+ parse_and_run_string(s);
+ _exit(G.last_return_code);
+#else
+ /* We re-execute after vfork on NOMMU. This makes this script safe:
+ * yes "0123456789012345678901234567890" | dd bs=32 count=64k >TESTFILE
+ * huge=`cat TESTFILE` # was blocking here forever
+ * echo OK
+ */
+//TODO: pass non-exported variables, traps, and functions
+ execl(CONFIG_BUSYBOX_EXEC_PATH, "hush", "-c", s, NULL);
+ _exit(127);
+#endif
}
+
+ /* parent */
close(channel[1]);
pf = fdopen(channel[0], "r");
return pf;
- /* 'head' is freed by the caller */
}
/* Return code is exit status of the process that is run. */
-static int process_command_subs(o_string *dest,
- struct in_str *input)
+static int process_command_subs(o_string *dest, const char *s)
{
- int retcode, ch, eol_cnt;
- struct pipe *pipe_list;
- FILE *p;
+ FILE *pf;
struct in_str pipe_str;
+ int ch, eol_cnt;
- /* Recursion to generate command */
- pipe_list = parse_stream(input, '\0');
- if (pipe_list == NULL)
- return 0; /* EOF: empty `cmd`: ``, ` ` etc */
- if (pipe_list == ERR_PTR)
- return 1; /* parse error. can this really happen? */
-
- p = generate_stream_from_list(pipe_list);
- free_pipe_list(pipe_list, /* indent: */ 0);
- if (p == NULL)
+ pf = generate_stream_from_string(s);
+ if (pf == NULL)
return 1;
- close_on_exec_on(fileno(p));
+ close_on_exec_on(fileno(pf));
/* Now send results of command back into original context */
- setup_file_in_str(&pipe_str, p);
+ setup_file_in_str(&pipe_str, pf);
eol_cnt = 0;
while ((ch = i_getch(&pipe_str)) != EOF) {
if (ch == '\n') {
@@ -3799,12 +3780,13 @@ static int process_command_subs(o_string *dest,
debug_printf("done reading from pipe, pclose()ing\n");
/* Note: we got EOF, and we just close the read end of the pipe.
* We do not wait for the `cmd` child to terminate. bash and ash do.
- * Try this:
- * echo `echo Hi; exec 1>&-; sleep 2`
+ * Try these:
+ * echo `echo Hi; exec 1>&-; sleep 2` - bash waits 2 sec
+ * `false`; echo $? - bash outputs "1"
*/
- retcode = fclose(p);
- debug_printf("closed FILE from child, retcode=%d\n", retcode);
- return retcode;
+ fclose(pf);
+ debug_printf("closed FILE from child. return 0\n");
+ return 0;
}
#endif
shell/hush_test/hush-misc/syntax_err.right+2 -0
@@ -1,2 +1,4 @@
shown
hush: syntax error: unterminated '
+test
+not shown