From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Graf Subject: Re: [PATCH 2.6 NET] Fixes slab corruption in cbq_destroy Date: Thu, 16 Sep 2004 16:09:43 +0200 Sender: netdev-bounce@oss.sgi.com Message-ID: <20040916140943.GC27293@postel.suug.ch> References: <20040916132856.GA27293@postel.suug.ch> <4149998C.6060501@trash.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "David S. Miller" , Alexey Kuznetsov , netdev@oss.sgi.com Return-path: To: Patrick McHardy Content-Disposition: inline In-Reply-To: <4149998C.6060501@trash.net> Errors-to: netdev-bounce@oss.sgi.com List-Id: netdev.vger.kernel.org * Patrick McHardy <4149998C.6060501@trash.net> 2004-09-16 15:47 > Thomas Graf wrote: > > >Fixes slab corruption in cbq_destroy. cbq_destroy_filters and > >qdisc_put_rtab(q->link.R_tab) are already called in cbq_destroy_class. > >The latter lead to a slab corruption due to repeated freeing of > >q->link.R_tab because q->link is part of q->classes. Problem introduced > >in 1.21. > > > > > I don't see how there can be slab corruption. qdisc_put_rtab only > calls kfree if the table is found in qdisc_rtab_list, which only > happens once. But the patch is still fine as cleanup :) On second call to qdisc_put_rtab with tab pointing to an already freed qdisc_rate_table: sch_api.c:271: if (!tab || --tab->refcnt) Sep 16 01:52:51 axs kernel: Slab corruption: start=d8bd4f30, len=2048 Sep 16 01:52:51 axs kernel: Redzone: 0x5a2cf071/0x5a2cf071. Sep 16 01:52:51 axs kernel: Last user: [](cbq_destroy_class+0x36/0x60) Sep 16 01:52:51 axs kernel: 410: 6a 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b ^^ I guess this is the --tab->refcnt Sep 16 01:52:51 axs kernel: Prev obj: start=d8bd4724, len=2048 Sep 16 01:52:51 axs kernel: Redzone: 0x170fc2a5/0x170fc2a5. Sep 16 01:52:51 axs kernel: Last user: [](qdisc_get_rtab+0x77/0xcd) Sep 16 01:52:51 axs kernel: 000: 04 00 00 00 00 00 40 00 20 bc be 00 05 00 00 00 Sep 16 01:52:51 axs kernel: 010: 05 00 00 00 05 00 00 00 05 00 00 00 05 00 00 00 Sep 16 01:52:51 axs kernel: Next obj: start=d8bd573c, len=2048 Sep 16 01:52:51 axs kernel: Redzone: 0x170fc2a5/0x170fc2a5. Sep 16 01:52:51 axs kernel: Last user: [](alloc_skb+0x48/0xe1) Sep 16 01:52:51 axs kernel: 000: 6c 04 00 00 28 00 05 06 d5 d5 48 41 00 00 00 00 Sep 16 01:52:51 axs kernel: 010: 00 00 00 00 04 00 00 00 12 00 10 00 00 00 10 00