[Ocfs2-devel] [PATCH 3/3] ocfs2: fix panic on nfs server over ocfs2

[Joseph Qi <joseph.qi@linux.alibaba.com>]

Hi Junxiao,

On 2020/6/12 08:19, Junxiao Bi wrote:
> The following kernel panic was captured when running nfs server over ocfs2,
> at that time ocfs2_test_inode_bit() was checking whether one inode locating
> at "blkno" 5 was valid, that is ocfs2 root inode, its "suballoc_slot" was
> OCFS2_INVALID_SLOT(65535) and it was allocted from //global_inode_alloc,
> but here it wrongly assumed that it was got from per slot inode alloctor
> which would cause array overflow and trigger kernel panic.
>
As you described, in this case suballoc_slot is OCFS2_INVALID_SLOT.
Why it hasn't trigger the "BUG_ON(slot == OCFS2_INVALID_SLOT)" in
get_local_system_inode()?

Thanks,
Joseph
 
> [430033.469151] BUG: unable to handle kernel paging request at
> 0000000000001088
> [430033.469367] IP: [<ffffffff816f6898>] _raw_spin_lock+0x18/0xf0
> [430033.469567] PGD 1e06ba067 PUD 1e9e7d067 PMD 0
> [430033.469769] Oops: 0002 [#1] SMP
> [430033.469975] Modules linked in: tun nfsd lockd grace nfs_acl auth_rpcgss
> ocfs2 xen_netback xen_blkback xen_gntalloc xen_gntdev xen_evtchn xenfs
> xen_privcmd ocfs2_dlmfs ocfs2_stack_o2cb ocfs2_dlm ocfs2_nodemanager
> ocfs2_stackglue configfs bnx2fc fcoe libfcoe libfc sunrpc bridge 8021q mrp
> garp stp llc bonding dm_round_robin scsi_dh_emc dm_multipath iTCO_wdt
> iTCO_vendor_support pcspkr sb_edac edac_core i2c_i801 i2c_core lpc_ich
> mfd_core sg ext4 jbd2 mbcache2 sd_mod ahci libahci lpfc scsi_transport_fc
> be2net vxlan udp_tunnel ip6_udp_tunnel mpt3sas scsi_transport_sas raid_class
> crc32c_intel be2iscsi bnx2i cnic uio cxgb4i cxgb4 cxgb3i libcxgbi ipv6 cxgb3
> mdio libiscsi_tcp qla4xxx iscsi_boot_sysfs libiscsi scsi_transport_iscsi
> dm_mirror dm_region_hash dm_log dm_mod
> [430033.472350] CPU: 6 PID: 24873 Comm: nfsd Not tainted
> 4.1.12-124.36.1.el6uek.x86_64 #2
> [430033.472719] Hardware name: Huawei CH121 V3/IT11SGCA1, BIOS 3.87
> 02/02/2018
> [430033.472910] task: ffff88005ae98000 ti: ffff88005ae94000 task.ti:
> ffff88005ae94000
> [430033.473277] RIP: e030:[<ffffffff816f6898>]  [<ffffffff816f6898>]
> _raw_spin_lock+0x18/0xf0
> [430033.473655] RSP: e02b:ffff88005ae97908  EFLAGS: 00010206
> [430033.473850] RAX: ffff88005ae98000 RBX: 0000000000001088 RCX:
> 0000000000000000
> [430033.474205] RDX: 0000000000020000 RSI: 0000000000000009 RDI:
> 0000000000001088
> [430033.474574] RBP: ffff88005ae97928 R08: 0000000000000000 R09:
> ffff880212878e00
> [430033.474938] R10: 0000000000007ff0 R11: 0000000000000000 R12:
> 0000000000001088
> [430033.475324] R13: ffff8800063c0aa8 R14: ffff8800650c27d0 R15:
> 000000000000ffff
> [430033.475721] FS:  0000000000000000(0000) GS:ffff880218180000(0000)
> knlGS:ffff880218180000
> [430033.476199] CS:  e033 DS: 0000 ES: 0000 CR0: 0000000080050033
> [430033.476390] CR2: 0000000000001088 CR3: 00000002033d0000 CR4:
> 0000000000042660
> [430033.476760] Stack:
> [430033.476942]  0000000000001000 0000000000001088 ffff8800063c0aa8
> ffff8800650c27d0
> [430033.477329]  ffff88005ae97948 ffffffff8122a3de 0000000000000009
> ffff8800063c0000
> [430033.477718]  ffff88005ae979e8 ffffffffc0714e43 ffff88005ae97968
> ffff88019de8f958
> [430033.478104] Call Trace:
> [430033.478286]  [<ffffffff8122a3de>] igrab+0x1e/0x60
> [430033.478494]  [<ffffffffc0714e43>] ocfs2_get_system_file_inode+0x63/0x3a0
> [ocfs2]
> [430033.478870]  [<ffffffffc06a87df>] ? ocfs2_read_blocks_sync+0x13f/0x3c0
> [ocfs2]
> [430033.479267]  [<ffffffffc06ff2d8>] ocfs2_test_inode_bit+0x328/0xa00
> [ocfs2]
> [430033.479498]  [<ffffffffc06bef5a>] ocfs2_get_parent+0xba/0x3e0 [ocfs2]
> [430033.479730]  [<ffffffff8129b305>] reconnect_path+0xb5/0x300
> [430033.479933]  [<ffffffff8129b646>] exportfs_decode_fh+0xf6/0x2b0
> [430033.480124]  [<ffffffffc0814af0>] ? nfsd_proc_getattr+0xa0/0xa0 [nfsd]
> [430033.480294]  [<ffffffffc081a682>] ? exp_find+0xe2/0x190 [nfsd]
> [430033.480461]  [<ffffffff810e5a7e>] ? irq_get_irq_data+0xe/0x10
> [430033.480627]  [<ffffffff810ea1a7>] ? __call_rcu_nocb_enqueue+0xd7/0xe0
> [430033.480794]  [<ffffffff810eb9e8>] ? __call_rcu+0xe8/0x360
> [430033.480959]  [<ffffffffc0815860>] fh_verify+0x350/0x660 [nfsd]
> [430033.481134]  [<ffffffffc0535076>] ? cache_check+0x56/0x3a0 [sunrpc]
> [430033.481317]  [<ffffffffc0823a4d>] nfsd4_putfh+0x4d/0x60 [nfsd]
> [430033.481505]  [<ffffffffc0826003>] nfsd4_proc_compound+0x3d3/0x6f0 [nfsd]
> [430033.481730]  [<ffffffffc0811f60>] nfsd_dispatch+0xe0/0x290 [nfsd]
> [430033.481950]  [<ffffffffc052b752>] ? svc_tcp_adjust_wspace+0x12/0x30
> [sunrpc]
> [430033.482152]  [<ffffffffc052a512>] svc_process_common+0x412/0x6a0 [sunrpc]
> [430033.482351]  [<ffffffffc052a8c3>] svc_process+0x123/0x210 [sunrpc]
> [430033.482550]  [<ffffffffc081190f>] nfsd+0xff/0x170 [nfsd]
> [430033.482744]  [<ffffffffc0811810>] ? nfsd_destroy+0x80/0x80 [nfsd]
> [430033.482943]  [<ffffffff810a7aeb>] kthread+0xcb/0xf0
> [430033.483151]  [<ffffffff816f10ea>] ? __schedule+0x24a/0x810
> [430033.483354]  [<ffffffff816f10ea>] ? __schedule+0x24a/0x810
> [430033.483553]  [<ffffffff810a7a20>] ? kthread_create_on_node+0x180/0x180
> [430033.483777]  [<ffffffff816f72a1>] ret_from_fork+0x61/0x90
> [430033.483976]  [<ffffffff810a7a20>] ? kthread_create_on_node+0x180/0x180
> [430033.484191] Code: 83 c2 02 0f b7 f2 e8 18 dc 91 ff 66 90 eb bf 0f 1f 40
> 00 55 48 89 e5 41 56 41 55 41 54 53 0f 1f 44 00 00 48 89 fb ba 00 00 02 00
> <f0> 0f c1 17 89 d0 45 31 e4 45 31 ed c1 e8 10 66 39 d0 41 89 c6
> [430033.485174] RIP  [<ffffffff816f6898>] _raw_spin_lock+0x18/0xf0
> [430033.485370]  RSP <ffff88005ae97908>
> [430033.485566] CR2: 0000000000001088
> [430033.486223] ---[ end trace 7264463cd1aac8f9 ]---
> [430033.666368] Kernel panic - not syncing: Fatal exception
> 
> Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com>
> ---
>  fs/ocfs2/suballoc.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/fs/ocfs2/suballoc.c b/fs/ocfs2/suballoc.c
> index 4836becb7578..45745cc3408a 100644
> --- a/fs/ocfs2/suballoc.c
> +++ b/fs/ocfs2/suballoc.c
> @@ -2825,9 +2825,12 @@ int ocfs2_test_inode_bit(struct ocfs2_super *osb, u64 blkno, int *res)
>  		goto bail;
>  	}
>  
> -	inode_alloc_inode =
> -		ocfs2_get_system_file_inode(osb, INODE_ALLOC_SYSTEM_INODE,
> -					    suballoc_slot);
> +	if (suballoc_slot == (u16)OCFS2_INVALID_SLOT)
> +		inode_alloc_inode = ocfs2_get_system_file_inode(osb,
> +			GLOBAL_INODE_ALLOC_SYSTEM_INODE, suballoc_slot);
> +	else
> +		inode_alloc_inode = ocfs2_get_system_file_inode(osb,
> +			INODE_ALLOC_SYSTEM_INODE, suballoc_slot);
>  	if (!inode_alloc_inode) {
>  		/* the error code could be inaccurate, but we are not able to
>  		 * get the correct one. */
>