Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752146AbbGaNph (ORCPT ); Fri, 31 Jul 2015 09:45:37 -0400 Received: from mail-yk0-f178.google.com ([209.85.160.178]:32991 "EHLO mail-yk0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751943AbbGaNpg convert rfc822-to-8bit (ORCPT ); Fri, 31 Jul 2015 09:45:36 -0400 MIME-Version: 1.0 In-Reply-To: References: Date: Fri, 31 Jul 2015 16:45:35 +0300 Message-ID: Subject: Re: Null pointer dereference in UDP4 core on AVR32 ATNGW100 From: Andy Shevchenko To: netdev , "linux-kernel@vger.kernel.org" Cc: "David S. Miller" , Nicolas Ferre , Eric Dumazet , David Held , Hans-Christian Egtvedt Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3728 Lines: 109 On Fri, Jul 31, 2015 at 4:25 PM, Andy Shevchenko wrote: > Hi! > > Got few weeks ago an old AVR32 board (ATNGW100). > It has ethernet cards supported by macb driver. > > Bring it mostly back to work with recent kernel from linux-next. Now, > when I start networking on it, I got in few seconds kernel panic. Seems the hack fixes this (still playing with network connected). # uname -a Linux buildroot 4.2.0-rc4-next-20150731+ #164 Fri Jul 31 16:37:20 EEST 2015 avr32 GNU/Linux --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1665,6 +1665,10 @@ static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb, unsigned int hash2 = 0, hash2_any = 0, use_hash2 = (hslot->count > 10); bool inner_flushed = false; +#ifdef CONFIG_AVR32 + use_hash2 = 0; +#endif + if (use_hash2) { hash2_any = udp4_portaddr_hash(net, htonl(INADDR_ANY), hnum) & udp_table.mask; > > Unable to handle kernel NULL pointer dereference at virtual address 00000000 > ptbr = 91e42000 pgd = 91e4b000 > Oops: Kernel access of bad area, sig: 11 [#1] > FRAME_POINTER chip: 0x01f:0x1e82 rev 2 > Modules linked in: > CPU: 0 PID: 0 Comm: swapper Not tainted 4.2.0-rc4-next-20150729+ #102 > task: 903532dc ti: 90350000 task.ti: 90350000 > PC is at __udp4_lib_rcv+0x300/0x660 > LR is at 0x15da8a2f > pc : [<90233a84>] lr : [<15da8a2f>] Not tainted > 0sp : 90351b5c r12: 00000000 r11: 91cd4450 > r10: 00000000 r9 : 0000004c r8 : 00000000 > r7 : 90351c80 r6 : 91db5c80 r5 : 91e4e540 r4 : 11f6a114 > r3 : 00000000 r2 : 91e6b224 r1 : 0000008a r0 : 00000000 > Flags: qvnZc > Mode bits: hjmde....g > CPU Mode: Interrupt level 0 > Stack: (0x90351b5c to 0x90352000) > … > Call trace: > [<90233df0>] udp_rcv+0xc/0x14 > [<90215220>] ip_local_deliver_finish+0xac/0x15c > [<902150ca>] ip_local_deliver+0x76/0x84 > [<90214d32>] ip_rcv_finish+0x23a/0x250 > [<90215004>] ip_rcv+0x2bc/0x30c > [<901f5ee4>] __netif_receive_skb_core+0x548/0x570 > [<901f5f52>] __netif_receive_skb+0x46/0x50 > [<901f5f8e>] netif_receive_skb_internal+0x32/0x3c > [<901f5fa0>] netif_receive_skb_sk+0x8/0xc > [<901cf358>] macb_rx+0x1b0/0x1d8 > [<901cf4d8>] macb_poll+0x38/0xa4 > [<901faf9c>] net_rx_action+0x84/0x1b4 > [<90021e46>] __do_softirq+0x5a/0x150 > [<90021f86>] irq_exit+0x26/0x58 > [<9001a520>] do_IRQ+0x34/0x44 > [<90019428>] irq_level0+0x18/0x5c > [<900355a4>] default_idle_call+0x1c/0x20 > [<9003563e>] cpu_startup_entry+0x66/0xa8 > [<902a16a4>] rest_init+0x48/0x70 > [<900007fc>] start_kernel+0x290/0x2dc > > Long time bisecting and reading assembly points to the > > commit 2dc41cff7545d55c6294525c811594576f8e119c > Author: David Held > Date: Tue Jul 15 23:28:32 2014 -0400 > > udp: Use hash2 for long hash1 chains in __udp*_lib_mcast_deliver. > > I don't know yet neither the package exactly makes this (tried to > debug print, but bug disappears) nor should be network card driver > fixed, or even compiler / binutils problems (using it from buildroot, > which is gcc 4.2.2). Would like to hear opinions what the root cause > might be and what ways we have to fix it. I'm also wondering if any > other architecture with same network card has the issue. > > P.S. > Since buildroot is not supporting anymore avr32 I use the version just > before this removal. (Nicolas, does Atmel care about that?) > > -- > With Best Regards, > Andy Shevchenko -- With Best Regards, Andy Shevchenko -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/