From 7a6d57235c41df877b3fb2322cf770e65e864058 Mon Sep 17 00:00:00 2001
From: Frans Kaashoek <kaashoek@mit.edu>
Date: Fri, 12 Aug 2022 14:59:30 -0400
Subject: [PATCH] Costmestic change (thanks Harry Porter)
---
kernel/syscall.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/kernel/syscall.c b/kernel/syscall.c
index 95b9f70..dd7a33e 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -12,7 +12,7 @@ int
fetchaddr(uint64 addr, uint64 *ip)
{
struct proc *p = myproc();
- if(addr >= p->sz || addr+sizeof(uint64) > p->sz)
+ if(addr >= p->sz || addr+sizeof(uint64) > p->sz) // both tests needed, in case of overflow
return -1;
if(copyin(p->pagetable, (char *)ip, addr, sizeof(*ip)) != 0)
return -1;
@@ -25,9 +25,8 @@ int
fetchstr(uint64 addr, char *buf, int max)
{
struct proc *p = myproc();
- int err = copyinstr(p->pagetable, buf, addr, max);
- if(err < 0)
- return err;
+ if(copyinstr(p->pagetable, buf, addr, max) < 0)
+ return -1;
return strlen(buf);
}