[PATCH 3.10 49/80] NFSv4: fix NULL dereference in open recover

From: Greg Kroah-Hartman
Date: Tue Nov 26 2013 - 20:50:46 EST

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

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

From: Weston Andros Adamson <dros@xxxxxxxxxx>

commit f494a6071d31e3294a3b51ad7a3684f983953f9f upstream.

_nfs4_opendata_reclaim_to_nfs4_state doesn't expect to see a cached
open CLAIM_PREVIOUS, but this can happen. An example is when there are
RDWR openers and RDONLY openers on a delegation stateid. The recovery
path will first try an open CLAIM_PREVIOUS for the RDWR openers, this
marks the delegation as not needing RECLAIM anymore, so the open
CLAIM_PREVIOUS for the RDONLY openers will not actually send an rpc.

The NULL dereference is due to _nfs4_opendata_reclaim_to_nfs4_state
returning PTR_ERR(rpc_status) when !rpc_done. When the open is
cached, rpc_done == 0 and rpc_status == 0, thus
_nfs4_opendata_reclaim_to_nfs4_state returns NULL - this is unexpected
by callers of nfs4_opendata_to_nfs4_state().

This can be reproduced easily by opening the same file two times on an
NFSv4.0 mount with delegations enabled, once as RDWR and once as RDONLY then
sleeping for a long time. While the files are held open, kick off state
recovery and this NULL dereference will be hit every time.

An example OOPS:

[ 65.003602] BUG: unable to handle kernel NULL pointer dereference at 00000000
00000030
[ 65.005312] IP: [<ffffffffa037d6ee>] __nfs4_close+0x1e/0x160 [nfsv4]
[ 65.006820] PGD 7b0ea067 PUD 791ff067 PMD 0
[ 65.008075] Oops: 0000 [#1] SMP
[ 65.008802] Modules linked in: rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache
snd_ens1371 gameport nfsd snd_rawmidi snd_ac97_codec ac97_bus btusb snd_seq snd
_seq_device snd_pcm ppdev bluetooth auth_rpcgss coretemp snd_page_alloc crc32_pc
lmul crc32c_intel ghash_clmulni_intel microcode rfkill nfs_acl vmw_balloon serio
_raw snd_timer lockd parport_pc e1000 snd soundcore parport i2c_piix4 shpchp vmw
_vmci sunrpc ata_generic mperf pata_acpi mptspi vmwgfx ttm scsi_transport_spi dr
m mptscsih mptbase i2c_core
[ 65.018684] CPU: 0 PID: 473 Comm: 192.168.10.85-m Not tainted 3.11.2-201.fc19
.x86_64 #1
[ 65.020113] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop
Reference Platform, BIOS 6.00 07/31/2013
[ 65.022012] task: ffff88003707e320 ti: ffff88007b906000 task.ti: ffff88007b906000
[ 65.023414] RIP: 0010:[<ffffffffa037d6ee>] [<ffffffffa037d6ee>] __nfs4_close+0x1e/0x160 [nfsv4]
[ 65.025079] RSP: 0018:ffff88007b907d10 EFLAGS: 00010246
[ 65.026042] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
[ 65.027321] RDX: 0000000000000050 RSI: 0000000000000001 RDI: 0000000000000000
[ 65.028691] RBP: ffff88007b907d38 R08: 0000000000016f60 R09: 0000000000000000
[ 65.029990] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001
[ 65.031295] R13: 0000000000000050 R14: 0000000000000000 R15: 0000000000000001
[ 65.032527] FS: 0000000000000000(0000) GS:ffff88007f600000(0000) knlGS:0000000000000000
[ 65.033981] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 65.035177] CR2: 0000000000000030 CR3: 000000007b27f000 CR4: 00000000000407f0
[ 65.036568] Stack:
[ 65.037011] 0000000000000000 0000000000000001 ffff88007b907d90 ffff88007a880220
[ 65.038472] ffff88007b768de8 ffff88007b907d48 ffffffffa037e4a5 ffff88007b907d80
[ 65.039935] ffffffffa036a6c8 ffff880037020e40 ffff88007a880000 ffff880037020e40
[ 65.041468] Call Trace:
[ 65.042050] [<ffffffffa037e4a5>] nfs4_close_state+0x15/0x20 [nfsv4]
[ 65.043209] [<ffffffffa036a6c8>] nfs4_open_recover_helper+0x148/0x1f0 [nfsv4]
[ 65.044529] [<ffffffffa036a886>] nfs4_open_recover+0x116/0x150 [nfsv4]
[ 65.045730] [<ffffffffa036d98d>] nfs4_open_reclaim+0xad/0x150 [nfsv4]
[ 65.046905] [<ffffffffa037d979>] nfs4_do_reclaim+0x149/0x5f0 [nfsv4]
[ 65.048071] [<ffffffffa037e1dc>] nfs4_run_state_manager+0x3bc/0x670 [nfsv4]
[ 65.049436] [<ffffffffa037de20>] ? nfs4_do_reclaim+0x5f0/0x5f0 [nfsv4]
[ 65.050686] [<ffffffffa037de20>] ? nfs4_do_reclaim+0x5f0/0x5f0 [nfsv4]
[ 65.051943] [<ffffffff81088640>] kthread+0xc0/0xd0
[ 65.052831] [<ffffffff81088580>] ? insert_kthread_work+0x40/0x40
[ 65.054697] [<ffffffff8165686c>] ret_from_fork+0x7c/0xb0
[ 65.056396] [<ffffffff81088580>] ? insert_kthread_work+0x40/0x40
[ 65.058208] Code: 5c 41 5d 5d c3 0f 1f 84 00 00 00 00 00 66 66 66 66 90 55 48 89 e5 41 57 41 89 f7 41 56 41 89 ce 41 55 41 89 d5 41 54 53 48 89 fb <4c> 8b 67 30 f0 41 ff 44 24 44 49 8d 7c 24 40 e8 0e 0a 2d e1 44
[ 65.065225] RIP [<ffffffffa037d6ee>] __nfs4_close+0x1e/0x160 [nfsv4]
[ 65.067175] RSP <ffff88007b907d10>
[ 65.068570] CR2: 0000000000000030
[ 65.070098] ---[ end trace 0d1fe4f5c7dd6f8b ]---

Signed-off-by: Weston Andros Adamson <dros@xxxxxxxxxx>
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/nfs/nfs4proc.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/fs/nfs/nfs4proc.c
+++ b/fs/nfs/nfs4proc.c
@@ -1159,7 +1159,8 @@ _nfs4_opendata_reclaim_to_nfs4_state(str
struct nfs4_state *state = data->state;
int ret;

- if (!data->rpc_done) {
+ /* allow cached opens (!rpc_done && !rpc_status) */
+ if (!data->rpc_done && data->rpc_status) {
ret = data->rpc_status;
goto err;
}


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