From 00572496ce8e2e3919586a0ce3df1fc457220ae5 Mon Sep 17 00:00:00 2001 From: cinap_lenrek Date: Fri, 6 Nov 2015 17:27:15 +0100 Subject: [PATCH] kernel: use nicer check in okaddr(), wet floor signs in fixfault() instead of checking addr+len >= addr, check len >= -addr so that addr == 0 is never valid for len > 0 even if we decide to have memory at the zero page so theres never any chance user can pass in "nil" pointers. put up some signs where we fall thru the switch cases in fixfault() --- sys/src/9/port/fault.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/sys/src/9/port/fault.c b/sys/src/9/port/fault.c index 64832d23f..0d5e1ac5a 100644 --- a/sys/src/9/port/fault.c +++ b/sys/src/9/port/fault.c @@ -237,10 +237,8 @@ fixfault(Segment *s, uintptr addr, int read) return -1; *pg = new; } - goto common; - - case SG_DATA: - common: /* Demand load/pagein/copy on write */ + /* wet floor */ + case SG_DATA: /* Demand load/pagein/copy on write */ if(pagedout(*pg)) pio(s, addr, soff, pg); @@ -279,6 +277,7 @@ fixfault(Segment *s, uintptr addr, int read) new->ref = 1; *pg = new; } + /* wet floor */ case SG_FIXED: /* Never paged out */ if (checkaddr && addr == addr2check) (*checkaddr)(addr, s, *pg); @@ -301,7 +300,7 @@ okaddr(uintptr addr, ulong len, int write) { Segment *s; - if((long)len >= 0 && addr+len >= addr) { + if((long)len >= 0 && len <= -addr) { for(;;) { s = seg(up, addr, 0); if(s == nil || (write && (s->type&SG_RONLY)))