ref: 7314601f9d9633c08f35d6ac1a5be834b0a8028a
parent: 4f2bf182bf7ad1750fc001ccc8a6d09cb00f10fa
author: cinap_lenrek <[email protected]>
date: Tue Mar 1 18:54:37 EST 2016
pppoe: Avoid double free (thanks k0ga) k0ga reports: Hello, While I was setting my pppoe conexion with my ISP I discovered several problems in ip/pppoe. I used the command line ip/pppoe -A '' ether0 and I got this: ... dropping unwanted pkt: wrong ac name panic: D2B called on non-block dc10 (double-free?) note rcved: sys: trap: fault read addr=0x0 pc=0x000066e1 pppoe 1013: suicide: sys: trap: fault read addr=0x0 pc=0x000066e1 cpu% acid 1013 /proc/1013/text:386 plan 9 executable /sys/lib/acid/port /sys/lib/acid/386 acid: stk() abort()+0x0 /sys/src/libc/9sys/abort.c:6 ppanic(p=0xd1b8,fmt=0xc7f9)+0x146 /sys/src/libc/port/malloc.c:166 D2B(p=0xd1b8,v=0xdc10)+0x57 /sys/src/libc/port/pool.c:926 poolfreel(v=0xdc10,p=0xd1b8)+0x20 /sys/src/libc/port/pool.c:1152 poolfree(p=0xd1b8,v=0xdc10)+0x3b /sys/src/libc/port/pool.c:1287 free(v=0xdc18)+0x23 /sys/src/libc/port/malloc.c:250 clearstate()+0x1b /sys/src/cmd/ip/pppoe.c:328 pppoe(ether=0xdfffefc1)+0x123 /sys/src/cmd/ip/pppoe.c:426 main(argv=0xdfffefa0,argc=0x1)+0x89 /sys/src/cmd/ip/pppoe.c:100 _main+0x31 /sys/src/libc/386/main9.s:16 acid: clearstate() is called in pppoe.c:424, and it frees acname and sets it to nil. pktread() is called in pppoe.c:434 with parameter wantoffer, which frees acname again in line pppoe.c:360 but doesn't set it to nil, so clearstate() makes a double free in the next iteration.
--- a/sys/src/cmd/ip/pppoe.c
+++ b/sys/src/cmd/ip/pppoe.c
@@ -358,6 +358,7 @@
acname = copy(s, len);
if(wantac && strcmp(acname, wantac) != 0){free(acname);
+ acname = nil;
return bad("wrong ac name");}