From: cinap_lenrek@felloff.net
To: 9fans@9fans.net
Subject: Re: [9fans] snprintf buffer overrun
Date: Sun, 27 Nov 2016 21:20:38 +0100 [thread overview]
Message-ID: <a1044862c8d3f5cd9a577d545ea80deb@felloff.net> (raw)
In-Reply-To: <583AF47A.4010400@mailinator.com>
theres a bug is in sclose() where it doesnt check if wp is beyond
the buffer. also wp was not updated after realloc().
--- a/sys/src/libstdio/sclose.c Sat Nov 19 16:47:21 2016 +0100
+++ b/sys/src/libstdio/sclose.c Sun Nov 27 21:07:48 2016 +0100
@@ -5,27 +5,35 @@
char *sclose(FILE *f){
switch(f->state){
default: /* ERR CLOSED */
+ Error:
if(f->buf && f->flags&BALLOC)
free(f->buf);
- f->flags=0;
- return NULL;
+ f->buf=0;
+ break;
case OPEN:
f->buf=malloc(1);
f->buf[0]='\0';
break;
case RD:
case END:
- f->flags=0;
break;
case RDWR:
case WR:
+ f->rp=f->buf+f->bufl;
if(f->wp==f->rp){
- if(f->flags&BALLOC)
- f->buf=realloc(f->buf, f->bufl+1);
- if(f->buf==NULL) return NULL;
+ if(f->flags&BALLOC){
+ char *t = realloc(f->buf, f->bufl+1);
+ if(t==NULL)
+ goto Error;
+ f->buf=t;
+ f->wp=t+f->bufl;
+ } else {
+ if(f->wp > f->buf)
+ *(f->wp-1) = '\0';
+ goto Error;
+ }
}
*f->wp='\0';
- f->flags=0;
break;
}
f->state=CLOSED;
--
cinap
next prev parent reply other threads:[~2016-11-27 20:20 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-27 14:58 Porlock
2016-11-27 20:20 ` cinap_lenrek [this message]
2016-11-27 20:31 ` cinap_lenrek
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