76ace254e

Denys Vlasenko

2009-10-12

FAILED Duration: 34s

Subject

ash,hush: fix $RANDOM in children being repeated

No binary (build failed)

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

—

(log yok)

shell/ash.c+4 -13

@@ -4725,10 +4725,12 @@ forkshell(struct job jp, union node n, int mode)
	freejob(jp);
	ash_msg_and_raise_error("can't fork");
	}
-	if (pid == 0)
+	if (pid == 0) {
+	CLEAR_RANDOM_T(&random_gen); /* or else $RANDOM repeats in child */
	forkchild(jp, n, mode);
-	else
+	} else {
	forkparent(jp, n, mode, pid);
+	}
	return pid;
	}

@@ -10079,12 +10081,6 @@ setcmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
	static void FAST_FUNC
	change_random(const char *value)
	{
-	/* Galois LFSR parameter */
-	/* Taps at 32 31 29 1: */
-	enum { MASK = 0x8000000b };
-	/* Another example - taps at 32 31 30 10: */
-	/* MASK = 0x00400007 */
-
	uint32_t t;

	if (value == NULL) {
@@ -13268,11 +13264,6 @@ int ash_main(int argc UNUSED_PARAM, char **argv)
	#endif
	rootpid = getpid();

-	#if ENABLE_ASH_RANDOM_SUPPORT
-	/* Can use monotonic_ns() for better randomness but for now it is
-	* not used anywhere else in busybox... so avoid bloat */
-	INIT_RANDOM_T(&random_gen, rootpid, monotonic_us());
-	#endif
	init();
	setstackmark(&smark);
	procargs(argv);

shell/hush.c+4 -2

@@ -88,6 +88,8 @@
	#include "match.h"
	#if ENABLE_HUSH_RANDOM_SUPPORT
	# include "random.h"
+	#else
+	# define CLEAR_RANDOM_T(rnd) ((void)0)
	#endif
	#ifndef PIPE_BUF
	# define PIPE_BUF 4096 /* amount of buffering in a pipe */
@@ -1319,8 +1321,6 @@ static const char get_local_var_value(const char name)
	// bash compat: UID? EUID?
	#if ENABLE_HUSH_RANDOM_SUPPORT
	if (strcmp(name, "RANDOM") == 0) {
-	if (G.random_gen.galois_LFSR == 0)
-	INIT_RANDOM_T(&G.random_gen, G.root_pid, monotonic_us());
	return utoa(next_random(&G.random_gen));
	}
	#endif
@@ -4000,6 +4000,7 @@ static NOINLINE int run_pipe(struct pipe *pi)
	if (!command->pid) { /* child */
	#if ENABLE_HUSH_JOB
	disable_restore_tty_pgrp_on_exit();
+	CLEAR_RANDOM_T(&G.random_gen); /* or else $RANDOM repeats in child */

	/* Every child adds itself to new process group
	* with pgid == pid_of_first_child_in_pipe */
@@ -5207,6 +5208,7 @@ static FILE generate_stream_from_string(const char s)
	+ (1 << SIGTTIN)
	+ (1 << SIGTTOU)
	, SIG_IGN);
+	CLEAR_RANDOM_T(&G.random_gen); /* or else $RANDOM repeats in child */
	close(channel[0]); /* NB: close _first_, then move fd! */
	xmove_fd(channel[1], 1);
	/* Prevent it from trying to handle ctrl-z etc */

shell/math.c+1 -1

@@ -258,7 +258,7 @@ static int
	arith_lookup_val(v_n_t t, a_e_h_t math_hooks)
	{
	if (t->var) {
-	const char * p = lookupvar(t->var);
+	const char *p = lookupvar(t->var);

	if (p) {
	int errcode;

shell/random.c+7 -0

@@ -20,6 +20,13 @@ next_random(random_t *rnd)

	uint32_t t;

+	if (UNINITED_RANDOM_T(rnd)) {
+	/* Can use monotonic_ns() for better randomness but for now
+	* it is not used anywhere else in busybox... so avoid bloat
+	*/
+	INIT_RANDOM_T(rnd, getpid(), monotonic_us());
+	}
+
	/* LCG has period of 2^32 and alternating lowest bit */
	rnd->LCG = 1664525 * rnd->LCG + 1013904223;
	/* Galois LFSR has period of 2^32-1 = 3 * 5 * 17 * 257 * 65537 */

shell/random.h+6 -0

@@ -13,7 +13,13 @@ typedef struct random_t {
	uint32_t LCG; /* LCG (fast but weak) */
	} random_t;

+	#define UNINITED_RANDOM_T(rnd) \
+	((rnd)->galois_LFSR == 0)
+
	#define INIT_RANDOM_T(rnd, nonzero, v) \
	((rnd)->galois_LFSR = (nonzero), (rnd)->LCG = (v))

+	#define CLEAR_RANDOM_T(rnd) \
+	((rnd)->galois_LFSR = 0)
+
	uint32_t next_random(random_t *rnd) FAST_FUNC;