1. 12 Dec, 2022 1 commit
    • Dan Aloni's avatar
      nfsd: under NFSv4.1, fix double svc_xprt_put on rpc_create failure · 3bc8edc9
      Dan Aloni authored
      On error situation `clp->cl_cb_conn.cb_xprt` should not be given
      a reference to the xprt otherwise both client cleanup and the
      error handling path of the caller call to put it. Better to
      delay handing over the reference to a later branch.
      
      [   72.530665] refcount_t: underflow; use-after-free.
      [   72.531933] WARNING: CPU: 0 PID: 173 at lib/refcount.c:28 refcount_warn_saturate+0xcf/0x120
      [   72.533075] Modules linked in: nfsd(OE) nfsv4(OE) nfsv3(OE) nfs(OE) lockd(OE) compat_nfs_ssc(OE) nfs_acl(OE) rpcsec_gss_krb5(OE) auth_rpcgss(OE) rpcrdma(OE) dns_resolver fscache netfs grace rdma_cm iw_cm ib_cm sunrpc(OE) mlx5_ib mlx5_core mlxfw pci_hyperv_intf ib_uverbs ib_core xt_MASQUERADE nf_conntrack_netlink nft_counter xt_addrtype nft_compat br_netfilter bridge stp llc nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set overlay nf_tables nfnetlink crct10dif_pclmul crc32_pclmul ghash_clmulni_intel xfs serio_raw virtio_net virtio_blk net_failover failover fuse [last unloaded: sunrpc]
      [   72.540389] CPU: 0 PID: 173 Comm: kworker/u16:5 Tainted: G           OE     5.15.82-dan #1
      [   72.541511] Hardware name: Red Hat KVM/RHEL-AV, BIOS 1.16.0-3.module+el8.7.0+1084+97b81f61 04/01/2014
      [   72.542717] Workqueue: nfsd4_callbacks nfsd4_run_cb_work [nfsd]
      [   72.543575] RIP: 0010:refcount_warn_saturate+0xcf/0x120
      [   72.544299] Code: 55 00 0f 0b 5d e9 01 50 98 00 80 3d 75 9e 39 08 00 0f 85 74 ff ff ff 48 c7 c7 e8 d1 60 8e c6 05 61 9e 39 08 01 e8 f6 51 55 00 <0f> 0b 5d e9 d9 4f 98 00 80 3d 4b 9e 39 08 00 0f 85 4c ff ff ff 48
      [   72.546666] RSP: 0018:ffffb3f841157cf0 EFLAGS: 00010286
      [   72.547393] RAX: 0000000000000026 RBX: ffff89ac6231d478 RCX: 0000000000000000
      [   72.548324] RDX: ffff89adb7c2c2c0 RSI: ffff89adb7c205c0 RDI: ffff89adb7c205c0
      [   72.549271] RBP: ffffb3f841157cf0 R08: 0000000000000000 R09: c0000000ffefffff
      [   72.550209] R10: 0000000000000001 R11: ffffb3f841157ad0 R12: ffff89ac6231d180
      [   72.551142] R13: ffff89ac6231d478 R14: ffff89ac40c06180 R15: ffff89ac6231d4b0
      [   72.552089] FS:  0000000000000000(0000) GS:ffff89adb7c00000(0000) knlGS:0000000000000000
      [   72.553175] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
      [   72.553934] CR2: 0000563a310506a8 CR3: 0000000109a66000 CR4: 0000000000350ef0
      [   72.554874] Call Trace:
      [   72.555278]  <TASK>
      [   72.555614]  svc_xprt_put+0xaf/0xe0 [sunrpc]
      [   72.556276]  nfsd4_process_cb_update.isra.11+0xb7/0x410 [nfsd]
      [   72.557087]  ? update_load_avg+0x82/0x610
      [   72.557652]  ? cpuacct_charge+0x60/0x70
      [   72.558212]  ? dequeue_entity+0xdb/0x3e0
      [   72.558765]  ? queued_spin_unlock+0x9/0x20
      [   72.559358]  nfsd4_run_cb_work+0xfc/0x270 [nfsd]
      [   72.560031]  process_one_work+0x1df/0x390
      [   72.560600]  worker_thread+0x37/0x3b0
      [   72.561644]  ? process_one_work+0x390/0x390
      [   72.562247]  kthread+0x12f/0x150
      [   72.562710]  ? set_kthread_struct+0x50/0x50
      [   72.563309]  ret_from_fork+0x22/0x30
      [   72.563818]  </TASK>
      [   72.564189] ---[ end trace 031117b1c72ec616 ]---
      [   72.566019] list_add corruption. next->prev should be prev (ffff89ac4977e538), but was ffff89ac4763e018. (next=ffff89ac4763e018).
      [   72.567647] ------------[ cut here ]------------
      
      Fixes: a4abc6b1 ("nfsd: Fix svc_xprt refcnt leak when setup callback client failed")
      Cc: Xiyu Yang <xiyuyang19@fudan.edu.cn>
      Cc: J. Bruce Fields <bfields@redhat.com>
      Signed-off-by: default avatarDan Aloni <dan.aloni@vastdata.com>
      Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
      Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
      3bc8edc9
  2. 11 Dec, 2022 1 commit
    • Jeff Layton's avatar
      nfsd: rework refcounting in filecache · ac3a2585
      Jeff Layton authored
      The filecache refcounting is a bit non-standard for something searchable
      by RCU, in that we maintain a sentinel reference while it's hashed. This
      in turn requires that we have to do things differently in the "put"
      depending on whether its hashed, which we believe to have led to races.
      
      There are other problems in here too. nfsd_file_close_inode_sync can end
      up freeing an nfsd_file while there are still outstanding references to
      it, and there are a number of subtle ToC/ToU races.
      
      Rework the code so that the refcount is what drives the lifecycle. When
      the refcount goes to zero, then unhash and rcu free the object. A task
      searching for a nfsd_file is allowed to bump its refcount, but only if
      it's not already 0. Ensure that we don't make any other changes to it
      until a reference is held.
      
      With this change, the LRU carries a reference. Take special care to deal
      with it when removing an entry from the list, and ensure that we only
      repurpose the nf_lru list_head when the refcount is 0 to ensure
      exclusive access to it.
      Signed-off-by: default avatarJeff Layton <jlayton@kernel.org>
      Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
      ac3a2585
  3. 10 Dec, 2022 21 commits
  4. 28 Nov, 2022 17 commits