Return-Path: Received: from mail-qg0-f65.google.com ([209.85.192.65]:35832 "EHLO mail-qg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750876AbcFDT5e (ORCPT ); Sat, 4 Jun 2016 15:57:34 -0400 Received: by mail-qg0-f65.google.com with SMTP id t106so4043946qgt.2 for ; Sat, 04 Jun 2016 12:57:34 -0700 (PDT) Message-ID: <1465070251.26749.4.camel@poochiereds.net> Subject: Re: [PATCH] nfs4: Fix potential use after free of state in nfs4_do_reclaim. From: Jeff Layton To: green@linuxhacker.ru, Trond Myklebust , Anna Schumaker Cc: Olga Kornievskaia , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org Date: Sat, 04 Jun 2016 15:57:31 -0400 In-Reply-To: <1465057313-2582381-1-git-send-email-green@linuxhacker.ru> References: <1465057313-2582381-1-git-send-email-green@linuxhacker.ru> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Sat, 2016-06-04 at 12:21 -0400, green@linuxhacker.ru wrote: > From: Oleg Drokin > > Commit e8d975e73e5f ("fixing infinite OPEN loop in 4.0 stateid recovery") > introduced access to state after it was just potentially freed by > nfs4_put_open_state leading to a random data corruption somewhere. > > BUG: unable to handle kernel paging request at ffff88004941ee40 > IP: [] nfs4_do_reclaim+0x461/0x740 > PGD 3501067 PUD 3504067 PMD 6ff37067 PTE 800000004941e060 > Oops: 0002 [#1] SMP DEBUG_PAGEALLOC > Modules linked in: loop rpcsec_gss_krb5 acpi_cpufreq tpm_tis joydev i2c_piix4 pcspkr tpm virtio_console nfsd ttm drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops floppy serio_raw virtio_blk drm > CPU: 6 PID: 2161 Comm: 192.168.10.253- Not tainted 4.7.0-rc1-vm-nfs+ #112 > Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 > task: ffff8800463dcd00 ti: ffff88003ff48000 task.ti: ffff88003ff48000 > RIP: 0010:[]  [] nfs4_do_reclaim+0x461/0x740 > RSP: 0018:ffff88003ff4bd68  EFLAGS: 00010246 > RAX: 0000000000000000 RBX: ffffffff81a49900 RCX: 00000000000000e8 > RDX: 00000000000000e8 RSI: ffff8800418b9930 RDI: ffff880040c96c88 > RBP: ffff88003ff4bdf8 R08: 0000000000000001 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: ffff880040c96c98 > R13: ffff88004941ee20 R14: ffff88004941ee40 R15: ffff88004941ee00 > FS:  0000000000000000(0000) GS:ffff88006d000000(0000) knlGS:0000000000000000 > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: ffff88004941ee40 CR3: 0000000060b0b000 CR4: 00000000000006e0 > Stack: >  ffffffff813baad5 ffff8800463dcd00 ffff880000000001 ffffffff810e6b68 >  ffff880043ddbc88 ffff8800418b9800 ffff8800418b98c8 ffff88004941ee48 >  ffff880040c96c90 ffff880040c96c00 ffff880040c96c20 ffff880040c96c40 > Call Trace: >  [] ? nfs4_do_reclaim+0x35/0x740 >  [] ? trace_hardirqs_on_caller+0x128/0x1b0 >  [] nfs4_run_state_manager+0x5ed/0xa40 >  [] ? nfs4_do_reclaim+0x740/0x740 >  [] ? nfs4_do_reclaim+0x740/0x740 >  [] kthread+0x101/0x120 >  [] ? trace_hardirqs_on_caller+0x128/0x1b0 >  [] ret_from_fork+0x1f/0x40 >  [] ? kthread_create_on_node+0x250/0x250 > Code: 65 80 4c 8b b5 78 ff ff ff e8 fc 88 4c 00 48 8b 7d 88 e8 13 67 d2 ff 49 8b 47 40 a8 02 0f 84 d3 01 00 00 4c 89 ff e8 7f f9 ff ff 41 80 26 7f 48 8b 7d c8 e8 b1 84 4c 00 e9 39 fd ff ff 3d e6 > RIP  [] nfs4_do_reclaim+0x461/0x740 >  RSP > CR2: ffff88004941ee40 > > Signed-off-by: Oleg Drokin > --- >  fs/nfs/nfs4state.c | 2 +- >  1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/nfs/nfs4state.c b/fs/nfs/nfs4state.c > index 9679f47..834b875 100644 > --- a/fs/nfs/nfs4state.c > +++ b/fs/nfs/nfs4state.c > @@ -1488,9 +1488,9 @@ restart: >   } >   spin_unlock(&state->state_lock); >   } > - nfs4_put_open_state(state); >   clear_bit(NFS_STATE_RECLAIM_NOGRACE, >   &state->flags); > + nfs4_put_open_state(state); >   spin_lock(&sp->so_lock); >   goto restart; >   } Nice catch. Reviewed-by: Jeff Layton