Re: [PATCH] NFS: Fix Oopses in nfs_lookup_revalidate and nfs4_lookup_revalidate

[Jeff Layton <jlayton@redhat.com>]

On Mon, 27 Aug 2012 13:23:11 -0700
Greg KH <gregkh@linuxfoundation.org> wrote:

> On Mon, Aug 27, 2012 at 08:16:09PM +0000, Myklebust, Trond wrote:
> > On Mon, 2012-08-27 at 13:09 -0700, Greg KH wrote:
> > > On Wed, Aug 22, 2012 at 04:08:17PM -0400, Trond Myklebust wrote:
> > > > Fix the following Oops in 3.5.1:
> > > > 
> > > >  BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
> > > >  IP: [<ffffffffa03789cd>] nfs_lookup_revalidate+0x2d/0x480 [nfs]
> > > >  PGD 337c63067 PUD 0
> > > >  Oops: 0000 [#1] SMP
> > > >  CPU 5
> > > >  Modules linked in: nfs fscache nfsd lockd nfs_acl auth_rpcgss sunrpc af_packet binfmt_misc cpufreq_conservative cpufreq_userspace cpufreq_powersave dm_mod acpi_cpufreq mperf coretemp gpio_ich kvm_intel joydev kvm ioatdma hid_generic igb lpc_ich i7core_edac edac_core ptp serio_raw dca pcspkr i2c_i801 mfd_core sg pps_core usbhid crc32c_intel microcode button autofs4 uhci_hcd ttm drm_kms_helper drm i2c_algo_bit sysimgblt sysfillrect syscopyarea ehci_hcd usbcore usb_common scsi_dh_rdac scsi_dh_emc scsi_dh_hp_sw scsi_dh_alua scsi_dh edd fan ata_piix thermal processor thermal_sys
> > > > 
> > > >  Pid: 30431, comm: java Not tainted 3.5.1-2-default #1 Supermicro X8DTT/X8DTT
> > > >  RIP: 0010:[<ffffffffa03789cd>]  [<ffffffffa03789cd>] nfs_lookup_revalidate+0x2d/0x480 [nfs]
> > > >  RSP: 0018:ffff8801b418bd38  EFLAGS: 00010292
> > > >  RAX: 00000000fffffff6 RBX: ffff88032016d800 RCX: 0000000000000020
> > > >  RDX: ffffffff00000000 RSI: 0000000000000000 RDI: ffff8801824a7b00
> > > >  RBP: ffff8801b418bdf8 R08: 7fffff0034323030 R09: fffffffff04c03ed
> > > >  R10: ffff8801824a7b00 R11: 0000000000000002 R12: ffff8801824a7b00
> > > >  R13: ffff8801824a7b00 R14: 0000000000000000 R15: ffff8803201725d0
> > > >  FS:  00002b53a46cb700(0000) GS:ffff88033fc20000(0000) knlGS:0000000000000000
> > > >  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > > >  CR2: 0000000000000038 CR3: 000000020a426000 CR4: 00000000000007e0
> > > >  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > > >  DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> > > >  Process java (pid: 30431, threadinfo ffff8801b418a000, task ffff8801b5d20600)
> > > >  Stack:
> > > >   ffff8801b418be44 ffff88032016d800 ffff8801b418bdf8 0000000000000000
> > > >   ffff8801824a7b00 ffff8801b418bdd7 ffff8803201725d0 ffffffff8116a9c0
> > > >   ffff8801b5c38dc0 0000000000000007 ffff88032016d800 0000000000000000
> > > >  Call Trace:
> > > >   [<ffffffff8116a9c0>] lookup_dcache+0x80/0xe0
> > > >   [<ffffffff8116aa43>] __lookup_hash+0x23/0x90
> > > >   [<ffffffff8116b4a5>] lookup_one_len+0xc5/0x100
> > > >   [<ffffffffa03869a3>] nfs_sillyrename+0xe3/0x210 [nfs]
> > > >   [<ffffffff8116cadf>] vfs_unlink.part.25+0x7f/0xe0
> > > >   [<ffffffff8116f22c>] do_unlinkat+0x1ac/0x1d0
> > > >   [<ffffffff815717b9>] system_call_fastpath+0x16/0x1b
> > > >   [<00002b5348b5f527>] 0x2b5348b5f526
> > > >  Code: ec 38 b8 f6 ff ff ff 4c 89 64 24 18 4c 89 74 24 28 49 89 fc 48 89 5c 24 08 48 89 6c 24 10 49 89 f6 4c 89 6c 24 20 4c 89 7c 24 30 <f6> 46 38 40 0f 85 d1 00 00 00 e8 c4 c4 df e0 48 8b 58 30 49 89
> > > >  RIP  [<ffffffffa03789cd>] nfs_lookup_revalidate+0x2d/0x480 [nfs]
> > > >   RSP <ffff8801b418bd38>
> > > >  CR2: 0000000000000038
> > > >  ---[ end trace 845113ed191985dd ]---
> > > > 
> > > > This Oops affects 3.5 kernels and older, and is due to lookup_one_len()
> > > > calling down to the dentry revalidation code with a NULL pointer
> > > > to struct nameidata.
> > > > 
> > > > It is fixed upstream by commit 0b728e1911c (stop passing nameidata *
> > > > to ->d_revalidate())
> > > 
> > > So this is just a nfs-only backport of the larger patch 0b728e1911c,
> > > right?  Should we also do this for other filesystems as well?  Or just
> > > backport the whole commit?
> > 
> > The larger patch involves a VFS api change (the atomic open code) which
> > has a bunch of pre- and post-requirements. I'd assume that is a too
> > large change for stable. I think that the smaller per-filesystem changes
> > are probably more appropriate. The list of filesystems that care are
> > likely to be small. Off the top of my head, I can only think of NFS,
> > CIFS, FUSE and possibly ceph.
> 
> Ok, I'll take this one for NFS, care to break this up also for FUSE and
> CIFS and send me a patch for it?
> 

A similar problem was already fixed quite some time ago in cifs in
commit f5bc1e755d, shortly after the RCU lookup code went in.

-- 
Jeff Layton <jlayton@redhat.com>