From db2efec0caba4f81a22d95a34da640b86c313c8e Mon Sep 17 00:00:00 2001 From: Jeff Layton Date: Tue, 30 Jun 2015 14:12:30 -0400 Subject: [PATCH] nfs: take extra reference to fl->fl_file when running a LOCKU operation Jean reported another crash, similar to the one fixed by feaff8e5b2cf: BUG: unable to handle kernel NULL pointer dereference at 0000000000000148 IP: [] locks_get_lock_context+0xf/0xa0 PGD 0 Oops: 0000 [#1] SMP Modules linked in: nfsv3 nfs_layout_flexfiles rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache vmw_vsock_vmci_transport vsock cfg80211 rfkill coretemp crct10dif_pclmul ppdev vmw_balloon crc32_pclmul crc32c_intel ghash_clmulni_intel pcspkr vmxnet3 parport_pc i2c_piix4 microcode serio_raw parport nfsd floppy vmw_vmci acpi_cpufreq auth_rpcgss shpchp nfs_acl lockd grace sunrpc vmwgfx drm_kms_helper ttm drm mptspi scsi_transport_spi mptscsih ata_generic mptbase i2c_core pata_acpi CPU: 0 PID: 329 Comm: kworker/0:1H Not tainted 4.1.0-rc7+ #2 Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/30/2013 Workqueue: rpciod rpc_async_schedule [sunrpc] 30ec000 RIP: 0010:[] [] locks_get_lock_context+0xf/0xa0 RSP: 0018:ffff8802330efc08 EFLAGS: 00010296 RAX: ffff8802330efc58 RBX: ffff880097187c80 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000 RBP: ffff8802330efc18 R08: ffff88023fc173d8 R09: 3038b7bf00000000 R10: 00002f1a02000000 R11: 3038b7bf00000000 R12: 0000000000000000 R13: 0000000000000000 R14: ffff8802337a2300 R15: 0000000000000020 FS: 0000000000000000(0000) GS:ffff88023fc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000148 CR3: 000000003680f000 CR4: 00000000001407f0 Stack: ffff880097187c80 ffff880097187cd8 ffff8802330efc98 ffffffff81250281 ffff8802330efc68 ffffffffa013e7df ffff8802330efc98 0000000000000246 ffff8801f6901c00 ffff880233d2b8d8 ffff8802330efc58 ffff8802330efc58 Call Trace: [] __posix_lock_file+0x31/0x5e0 [] ? rpc_wake_up_task_queue_locked.part.35+0xcf/0x240 [sunrpc] [] posix_lock_file_wait+0x3b/0xd0 [] ? nfs41_wake_and_assign_slot+0x32/0x40 [nfsv4] [] ? nfs41_sequence_done+0xd8/0x300 [nfsv4] [] do_vfs_lock+0x35/0x40 [nfsv4] [] nfs4_locku_done+0x81/0x120 [nfsv4] [] ? rpc_destroy_wait_queue+0x20/0x20 [sunrpc] [] ? rpc_destroy_wait_queue+0x20/0x20 [sunrpc] [] rpc_exit_task+0x2c/0x90 [sunrpc] [] ? call_refreshresult+0x170/0x170 [sunrpc] [] __rpc_execute+0x84/0x410 [sunrpc] [] rpc_async_schedule+0x15/0x20 [sunrpc] [] process_one_work+0x147/0x400 [] worker_thread+0x11b/0x460 [] ? rescuer_thread+0x2f0/0x2f0 [] kthread+0xc9/0xe0 [] ? perf_trace_xen_mmu_set_pmd+0xa0/0x160 [] ? kthread_create_on_node+0x170/0x170 [] ret_from_fork+0x42/0x70 [] ? kthread_create_on_node+0x170/0x170 Code: a5 81 e8 85 75 e4 ff c6 05 31 ee aa 00 01 eb 98 66 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 54 49 89 fc 53 <48> 8b 9f 48 01 00 00 48 85 db 74 08 48 89 d8 5b 41 5c 5d c3 83 RIP [] locks_get_lock_context+0xf/0xa0 RSP CR2: 0000000000000148 ---[ end trace 64484f16250de7ef ]--- The problem is almost exactly the same as the one fixed by feaff8e5b2cf. We must take a reference to the struct file when running the LOCKU compound to prevent the final fput from running until the operation is complete. Reported-by: Jean Spector Signed-off-by: Jeff Layton Cc: stable@vger.kernel.org Signed-off-by: Trond Myklebust --- fs/nfs/nfs4proc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index 605c203de556..5e7638d8e31b 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -5484,6 +5484,7 @@ static struct nfs4_unlockdata *nfs4_alloc_unlockdata(struct file_lock *fl, atomic_inc(&lsp->ls_count); /* Ensure we don't close file until we're done freeing locks! */ p->ctx = get_nfs_open_context(ctx); + get_file(fl->fl_file); memcpy(&p->fl, fl, sizeof(p->fl)); p->server = NFS_SERVER(inode); return p; @@ -5495,6 +5496,7 @@ static void nfs4_locku_release_calldata(void *data) nfs_free_seqid(calldata->arg.seqid); nfs4_put_lock_state(calldata->lsp); put_nfs_open_context(calldata->ctx); + fput(calldata->fl.fl_file); kfree(calldata); } -- 2.20.1