[ 92/95] NFS: Fix Oopses in nfs_lookup_revalidate and nfs4_lookup_revalidate

From: Ben Hutchings
Date: Sun Sep 09 2012 - 19:31:17 EST


3.2-stable review patch. If anyone has any objections, please let me know.

------------------

From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>

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())

Reported-by: Richard Ems <richard.ems@xxxxxxxxxxxxxxxxx>
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
fs/nfs/dir.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -1103,7 +1103,7 @@ static int nfs_lookup_revalidate(struct
struct nfs_fattr *fattr = NULL;
int error;

- if (nd->flags & LOOKUP_RCU)
+ if (nd && (nd->flags & LOOKUP_RCU))
return -ECHILD;

parent = dget_parent(dentry);
@@ -1508,7 +1508,7 @@ static int nfs_open_revalidate(struct de
struct nfs_open_context *ctx;
int openflags, ret = 0;

- if (nd->flags & LOOKUP_RCU)
+ if (nd && (nd->flags & LOOKUP_RCU))
return -ECHILD;

inode = dentry->d_inode;


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