NFSv4: fix possible NULL-pointer dereference in nfs42_complete_copies…

… after state recovery failed

On the node of an nfs client, some files saved in the mountpoint of the nfs server was coping within
the same nfs server. Accidentally, the nfs42_complete_copies get a NULL-pointer dereference crash, as
can be seen in following syslog:

[232064.838881] NFSv4: state recovery failed for open file nfs/pvc-12b5200d-cd0f-46a3-b9f0-af8f4fe0ef64.qcow2, error = -116
[232064.839360] NFSv4: state recovery failed for open file nfs/pvc-12b5200d-cd0f-46a3-b9f0-af8f4fe0ef64.qcow2, error = -116
[232066.588183] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000058
[232066.588586] Mem abort info:
[232066.588701]   ESR = 0x0000000096000007
[232066.588862]   EC = 0x25: DABT (current EL), IL = 32 bits
[232066.589084]   SET = 0, FnV = 0
[232066.589216]   EA = 0, S1PTW = 0
[232066.589340]   FSC = 0x07: level 3 translation fault
[232066.589559] Data abort info:
[232066.589683]   ISV = 0, ISS = 0x00000007
[232066.589842]   CM = 0, WnR = 0
[232066.589967] user pgtable: 64k pages, 48-bit VAs, pgdp=00002000956ff400
[232066.590231] [0000000000000058] pgd=08001100ae100003, p4d=08001100ae100003, pud=08001100ae100003, pmd=08001100b3c00003, pte=0000000000000000
[232066.590757] Internal error: Oops: 96000007 [#1] SMP
[232066.590958] Modules linked in: rpcsec_gss_krb5 auth_rpcgss nfsv4 dns_resolver nfs lockd grace fscache netfs ocfs2_dlmfs ocfs2_stack_o2cb ocfs2_dlm vhost_net vhost vhost_iotlb tap tun ipt_rpfilter xt_multiport ip_set_hash_ip ip_set_hash_net xfrm_interface xfrm6_tunnel tunnel4 tunnel6 esp4 ah4 wireguard libcurve25519_generic veth xt_addrtype xt_set nf_conntrack_netlink ip_set_hash_ipportnet ip_set_hash_ipportip ip_set_bitmap_port ip_set_hash_ipport dummy ip_set ip_vs_sh ip_vs_wrr ip_vs_rr ip_vs iptable_filter sch_ingress nfnetlink_cttimeout vport_gre ip_gre ip_tunnel gre vport_geneve geneve vport_vxlan vxlan ip6_udp_tunnel udp_tunnel openvswitch nf_conncount dm_round_robin dm_service_time dm_multipath xt_nat xt_MASQUERADE nft_chain_nat nf_nat xt_mark xt_conntrack xt_comment nft_compat nft_counter nf_tables nfnetlink ocfs2 ocfs2_nodemanager ocfs2_stackglue iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi ipmi_ssif nbd overlay 8021q garp mrp bonding tls rfkill sunrpc ext4 mbcache jbd2
[232066.591052]  vfat fat cas_cache cas_disk ses enclosure scsi_transport_sas sg acpi_ipmi ipmi_si ipmi_devintf ipmi_msghandler ip_tables vfio_pci vfio_pci_core vfio_virqfd vfio_iommu_type1 vfio dm_mirror dm_region_hash dm_log dm_mod nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 br_netfilter bridge stp llc fuse xfs libcrc32c ast drm_vram_helper qla2xxx drm_kms_helper syscopyarea crct10dif_ce sysfillrect ghash_ce sysimgblt sha2_ce fb_sys_fops cec sha256_arm64 sha1_ce drm_ttm_helper ttm nvme_fc igb sbsa_gwdt nvme_fabrics drm nvme_core i2c_algo_bit i40e scsi_transport_fc megaraid_sas aes_neon_bs
[232066.596953] CPU: 6 PID: 4124696 Comm: 10.253.166.125- Kdump: loaded Not tainted 5.15.131-9.cl9_ocfs2.aarch64 #1
[232066.597356] Hardware name: Great Wall .\x93\x8e...RF6260 V5/GWMSSE2GL1T, BIOS T656FBE_V3.0.18 2024-01-06
[232066.597721] pstate: 20400009 (nzCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[232066.598034] pc : nfs4_reclaim_open_state+0x220/0x800 [nfsv4]
[232066.598327] lr : nfs4_reclaim_open_state+0x12c/0x800 [nfsv4]
[232066.598595] sp : ffff8000f568fc70
[232066.598731] x29: ffff8000f568fc70 x28: 0000000000001000 x27: ffff21003db33000
[232066.599030] x26: ffff800005521ae0 x25: ffff0100f98fa3f0 x24: 0000000000000001
[232066.599319] x23: ffff800009920008 x22: ffff21003db33040 x21: ffff21003db33050
[232066.599628] x20: ffff410172fe9e40 x19: ffff410172fe9e00 x18: 0000000000000000
[232066.599914] x17: 0000000000000000 x16: 0000000000000004 x15: 0000000000000000
[232066.600195] x14: 0000000000000000 x13: ffff800008e685a8 x12: 00000000eac0c6e6
[232066.600498] x11: 0000000000000000 x10: 0000000000000008 x9 : ffff8000054e5828
[232066.600784] x8 : 00000000ffffffbf x7 : 0000000000000001 x6 : 000000000a9eb14a
[232066.601062] x5 : 0000000000000000 x4 : ffff70ff8a14a800 x3 : 0000000000000058
[232066.601348] x2 : 0000000000000001 x1 : 54dce46366daa6c6 x0 : 0000000000000000
[232066.601636] Call trace:
[232066.601749]  nfs4_reclaim_open_state+0x220/0x800 [nfsv4]
[232066.601998]  nfs4_do_reclaim+0x1b8/0x28c [nfsv4]
[232066.602218]  nfs4_state_manager+0x928/0x10f0 [nfsv4]
[232066.602455]  nfs4_run_state_manager+0x78/0x1b0 [nfsv4]
[232066.602690]  kthread+0x110/0x114
[232066.602830]  ret_from_fork+0x10/0x20
[232066.602985] Code: 1400000d f9403f20 f9402e61 91016003 (f9402c00)
[232066.603284] SMP: stopping secondary CPUs
[232066.606936] Starting crashdump kernel...
[232066.607146] Bye!

With the vmcore, we know that nfs4_copy_state listed by destination nfs_server->ss_copies was added with
the field copies in the handle_async_copy, and we found that waiting copy process with the stack as:
PID: 3511963  TASK: ffff710028b47e00  CPU: 0   COMMAND: "cp"
 #0 [ffff8001116ef740] __switch_to at ffff8000081b92f4
 #1 [ffff8001116ef760] __schedule at ffff800008dd0650
 #2 [ffff8001116ef7c0] schedule at ffff800008dd0a00
 #3 [ffff8001116ef7e0] schedule_timeout at ffff800008dd6aa0
 #4 [ffff8001116ef860] __wait_for_common at ffff800008dd166c
 #5 [ffff8001116ef8e0] wait_for_completion_interruptible at ffff800008dd1898
 torvalds#6 [ffff8001116ef8f0] handle_async_copy at ffff8000055142f4 [nfsv4]
 torvalds#7 [ffff8001116ef970] _nfs42_proc_copy at ffff8000055147c8 [nfsv4]
 torvalds#8 [ffff8001116efa80] nfs42_proc_copy at ffff800005514cf0 [nfsv4]
 torvalds#9 [ffff8001116efc50] __nfs4_copy_file_range.constprop.0 at ffff8000054ed694 [nfsv4]

We found that the NULL-pointer dereference was due to nfs42_complete_copies list the nfs_server->ss_copies
by the filed ss_copies of nfs4_copy_state. So the nfs4_copy_state address ffff0100f98fa3f0 is offset by 0x10
and the data accessed through this pointer is also incorrect. Generally, the nfs4_state_owner->so_states
list is ordered and open(O_RDWR) or open(O_WRITE) states are reclaimed firstly by nfs4_reclaim_open_state.
But when destination state was reclaimed failed with NFS_STATE_RECOVERY_FAILED and copies were not deleted
in nfs_server->ss_copies, the source state may be taken into nfs42_complete_copies earlier resulting in this
situation. To solve this, we newly add a list_head nfs_server->ds_copies for a server-to-server copy specially.

Fixes: b1a0913adbef ("NFS: handle source server reboot")
Signed-off-by: Yanjun Zhang <[email protected]>

fs/nfs/nfs42proc.c

@@ -218,7 +218,7 @@ static int handle_async_copy(struct nfs42_copy_res *res,
 
 	if (dst_server != src_server) {
 		spin_lock(&src_server->nfs_client->cl_lock);
-		list_add_tail(&copy->src_copies, &src_server->ss_copies);
+		list_add_tail(&copy->src_copies, &src_server->ds_copies);
 		spin_unlock(&src_server->nfs_client->cl_lock);
 	}
 

fs/nfs/nfs4state.c

@@ -1596,7 +1596,7 @@ static void nfs42_complete_copies(struct nfs4_state_owner *sp, struct nfs4_state
 			complete(&copy->completion);
 		}
 	}
-	list_for_each_entry(copy, &sp->so_server->ss_copies, src_copies) {
+	list_for_each_entry(copy, &sp->so_server->ds_copies, src_copies) {
 		if ((test_bit(NFS_CLNT_SRC_SSC_COPY_STATE, &state->flags) &&
 				!nfs4_stateid_match_other(&state->stateid,
 				&copy->parent_src_state->stateid)))

include/linux/nfs_fs_sb.h

@@ -240,6 +240,7 @@ struct nfs_server {
 	struct list_head	layouts;
 	struct list_head	delegations;
 	struct list_head	ss_copies;
+	struct list_head	ds_copies;
 
 	unsigned long		delegation_gen;
 	unsigned long		mig_gen;