From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vlad Yasevich Subject: Re: [PATCH] net: sctp: fix panic during skb_orphan() Date: Fri, 09 Aug 2013 20:39:14 -0400 Message-ID: <52058BB2.4010606@gmail.com> References: <20130809.133720.232424253997869104.davem@davemloft.net> <1376085487-6466-1-git-send-email-vyasevich@gmail.com> <1376090435.20509.13.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, davem@davemloft.net, linux-sctp@vger.kernel.org, dborkman@redhat.com To: Eric Dumazet Return-path: Received: from mail-ve0-f177.google.com ([209.85.128.177]:59375 "EHLO mail-ve0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S968048Ab3HJAjT (ORCPT ); Fri, 9 Aug 2013 20:39:19 -0400 In-Reply-To: <1376090435.20509.13.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: On 08/09/2013 07:20 PM, Eric Dumazet wrote: > On Fri, 2013-08-09 at 17:58 -0400, Vlad Yasevich wrote: >> This patch fixes the following triggered bug ... >> >> [ 553.109742] kernel BUG at include/linux/skbuff.h:1813! >> [ 553.109766] invalid opcode: 0000 [#1] SMP >> [ 553.109789] Modules linked in: sctp libcrc32c rfcomm [...] >> [ 553.110259] uinput i915 i2c_algo_bit drm_kms_helper e1000e drm ptp >> pps_core i2c_core wmi video sunrpc >> [ 553.110320] CPU: 0 PID: 1636 Comm: lt-test_1_to_1_ Not tainted >> 3.11.0-rc3+ #2 >> [ 553.110350] Hardware name: LENOVO 74597D6/74597D6, BIOS 6DET60WW >> (3.10 ) 09/17/2009 >> [ 553.110381] task: ffff88020a01dd40 ti: ffff880204ed0000 task.ti: >> ffff880204ed0000 >> [ 553.110411] RIP: 0010:[] [] >> skb_orphan.part.9+0x4/0x6 [sctp] >> [ 553.110459] RSP: 0018:ffff880204ed1bb8 EFLAGS: 00010286 >> [ 553.110483] RAX: ffff8802086f5a40 RBX: ffff880204303300 RCX: >> 0000000000000000 >> [ 553.110487] RDX: ffff880204303c28 RSI: ffff8802086f5a40 RDI: >> ffff880202158000 >> [ 553.110487] RBP: ffff880204ed1bb8 R08: 0000000000000000 R09: >> 0000000000000000 >> [ 553.110487] R10: ffff88022f2d9a04 R11: ffff880233001600 R12: >> 0000000000000000 >> [ 553.110487] R13: ffff880204303c00 R14: ffff8802293d0000 R15: >> ffff880202158000 >> [ 553.110487] FS: 00007f31b31fe740(0000) GS:ffff88023bc00000(0000) >> knlGS:0000000000000000 >> [ 553.110487] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b >> [ 553.110487] CR2: 000000379980e3e0 CR3: 000000020d225000 CR4: >> 00000000000407f0 >> [ 553.110487] Stack: >> [ 553.110487] ffff880204ed1ca8 ffffffffa068d7fc 0000000000000000 >> 0000000000000000 >> [ 553.110487] 0000000000000000 ffff8802293d0000 ffff880202158000 >> ffffffff81cb7900 >> [ 553.110487] 0000000000000000 0000400000001c68 ffff8802086f5a40 >> 000000000000000f >> [ 553.110487] Call Trace: >> [ 553.110487] [] sctp_sendmsg+0x6bc/0xc80 [sctp] >> [ 553.110487] [] ? sock_has_perm+0x75/0x90 >> [ 553.110487] [] inet_sendmsg+0x63/0xb0 >> [ 553.110487] [] ? selinux_socket_sendmsg+0x23/0x30 >> [ 553.110487] [] sock_sendmsg+0xa6/0xd0 >> [ 553.110487] [] ? _raw_spin_unlock_bh+0x15/0x20 >> [ 553.110487] [] SYSC_sendto+0x128/0x180 >> [ 553.110487] [] ? SYSC_connect+0xdb/0x100 >> [ 553.110487] [] ? sctp_inet_listen+0x71/0x1f0 >> [sctp] >> [ 553.110487] [] SyS_sendto+0xe/0x10 >> [ 553.110487] [] system_call_fastpath+0x16/0x1b >> [ 553.110487] Code: e0 48 c7 c7 00 22 6a a0 e8 67 a3 f0 e0 48 c7 [...] >> [ 553.110487] RIP [] skb_orphan.part.9+0x4/0x6 >> [sctp] >> [ 553.110487] RSP >> [ 553.121578] ---[ end trace 46c20c5903ef5be2 ]--- >> >> When a SCTP data chunk is created, skb->sk is set by sctp_make_chunk(). >> At a later time, sctp_sendmg() calls sctp_set_owner_w() which will attempt >> to orphan the skb and correctly set the skb->sk. The skb_orphan call result >> in the above crash since skb->sk was set the the destructor was not. >> >> The simple solution is to not set skb->sk for DATA chunks (since it >> will be done later). Continue to do it for control chunks since >> sctp needs the sk at a later timer and control chunks are not currently >> accouted agains socket memory. >> >> Signed-off-by: Vlad Yasevich >> --- >> net/sctp/sm_make_chunk.c | 8 ++++++-- >> 1 file changed, 6 insertions(+), 2 deletions(-) >> >> diff --git a/net/sctp/sm_make_chunk.c b/net/sctp/sm_make_chunk.c >> index 780a2d4..4ff7803 100644 >> --- a/net/sctp/sm_make_chunk.c >> +++ b/net/sctp/sm_make_chunk.c >> @@ -1385,8 +1385,12 @@ static struct sctp_chunk *sctp_make_chunk(const struct sctp_association *asoc, >> if (sctp_auth_send_cid(type, asoc)) >> retval->auth = 1; >> >> - /* Set the skb to the belonging sock for accounting. */ >> - skb->sk = sk; >> + /* Set the skb to the belonging sock for accounting. Do not >> + * do this for data chunks as that will be properly set >> + * up later. >> + */ >> + if (type != SCTP_CID_DATA) >> + skb->sk = sk; >> >> return retval; >> nodata: > > This is ugly IMHO. Yes, it is a bit ugly. The "proper" way is to do accounting for all SCTP chunks, but that is a much larger piece of work. > > Why not using a dummy destructor ? It would just be useless once we do proper accounting for all chunks. But, I'll send a different idea if this is just too ugly. > > And I guess this patch is for net-next ? > Yes, sorry... Anyway. I'll send an less ugly alternative... -vlad > >