Fix some security bugs in the SVR4 emulator:

- Return NULL instead of returning memory outside of the stackgap
  in stackgap_alloc() (FreeBSD-SA-00:42.linux)
- Check for stackgap_alloc() returning NULL in svr4_emul_find(),
  and clean_pipe().
- Avoid integer overflow on large nfds argument in svr4_sys_poll()
- Reject negative nbytes argument in svr4_sys_getdents()
- Don't copy out past the end of the struct componentname
  pathname buffer in svr4_sys_resolvepath()
- Reject out-of-range signal numbers in svr4_sys_sigaction(),
  svr4_sys_signal(), and svr4_sys_kill().
- Don't malloc() user-specified lengths in show_ioc() and
  show_strbuf(), place arbitrary limits instead.
- Range-check lengths in si_listen(), ti_getinfo(), ti_bind(),
  svr4_do_putmsg(), svr4_do_getmsg(), svr4_stream_ti_ioctl().

Some fixes obtain from OpenBSD.

1 files changed, 4 insertions, 1 deletions

diff --git a/sys/compat/svr4/svr4_util.h b/sys/compat/svr4/svr4_util.h
index 9e5be7f..e0cb54f 100644
--- a/sys/compat/svr4/svr4_util.h
+++ b/sys/compat/svr4/svr4_util.h
@@ -63,7 +63,10 @@ stackgap_alloc(sgp, sz)
 	size_t   sz;
 {
 	void	*p = (void *) *sgp;
-	*sgp += ALIGN(sz);
+	sz = ALIGN(sz);
+	if (*sgp + sz > (caddr_t)(PS_STRINGS - szsigcode))
+		return NULL;
+	*sgp += sz;
 	return p;
 }