linux-sg2042/include
David Howells 0837e49ab3 KEYS: Differentiate uses of rcu_dereference_key() and user_key_payload()
rcu_dereference_key() and user_key_payload() are currently being used in
two different, incompatible ways:

 (1) As a wrapper to rcu_dereference() - when only the RCU read lock used
     to protect the key.

 (2) As a wrapper to rcu_dereference_protected() - when the key semaphor is
     used to protect the key and the may be being modified.

Fix this by splitting both of the key wrappers to produce:

 (1) RCU accessors for keys when caller has the key semaphore locked:

	dereference_key_locked()
	user_key_payload_locked()

 (2) RCU accessors for keys when caller holds the RCU read lock:

	dereference_key_rcu()
	user_key_payload_rcu()

This should fix following warning in the NFS idmapper

  ===============================
  [ INFO: suspicious RCU usage. ]
  4.10.0 #1 Tainted: G        W
  -------------------------------
  ./include/keys/user-type.h:53 suspicious rcu_dereference_protected() usage!
  other info that might help us debug this:
  rcu_scheduler_active = 2, debug_locks = 0
  1 lock held by mount.nfs/5987:
    #0:  (rcu_read_lock){......}, at: [<d000000002527abc>] nfs_idmap_get_key+0x15c/0x420 [nfsv4]
  stack backtrace:
  CPU: 1 PID: 5987 Comm: mount.nfs Tainted: G        W       4.10.0 #1
  Call Trace:
    dump_stack+0xe8/0x154 (unreliable)
    lockdep_rcu_suspicious+0x140/0x190
    nfs_idmap_get_key+0x380/0x420 [nfsv4]
    nfs_map_name_to_uid+0x2a0/0x3b0 [nfsv4]
    decode_getfattr_attrs+0xfac/0x16b0 [nfsv4]
    decode_getfattr_generic.constprop.106+0xbc/0x150 [nfsv4]
    nfs4_xdr_dec_lookup_root+0xac/0xb0 [nfsv4]
    rpcauth_unwrap_resp+0xe8/0x140 [sunrpc]
    call_decode+0x29c/0x910 [sunrpc]
    __rpc_execute+0x140/0x8f0 [sunrpc]
    rpc_run_task+0x170/0x200 [sunrpc]
    nfs4_call_sync_sequence+0x68/0xa0 [nfsv4]
    _nfs4_lookup_root.isra.44+0xd0/0xf0 [nfsv4]
    nfs4_lookup_root+0xe0/0x350 [nfsv4]
    nfs4_lookup_root_sec+0x70/0xa0 [nfsv4]
    nfs4_find_root_sec+0xc4/0x100 [nfsv4]
    nfs4_proc_get_rootfh+0x5c/0xf0 [nfsv4]
    nfs4_get_rootfh+0x6c/0x190 [nfsv4]
    nfs4_server_common_setup+0xc4/0x260 [nfsv4]
    nfs4_create_server+0x278/0x3c0 [nfsv4]
    nfs4_remote_mount+0x50/0xb0 [nfsv4]
    mount_fs+0x74/0x210
    vfs_kern_mount+0x78/0x220
    nfs_do_root_mount+0xb0/0x140 [nfsv4]
    nfs4_try_mount+0x60/0x100 [nfsv4]
    nfs_fs_mount+0x5ec/0xda0 [nfs]
    mount_fs+0x74/0x210
    vfs_kern_mount+0x78/0x220
    do_mount+0x254/0xf70
    SyS_mount+0x94/0x100
    system_call+0x38/0xe0

Reported-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Jan Stancek <jstancek@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2017-03-02 10:09:00 +11:00
..
acpi Merge branches 'acpi-bus', 'acpi-sleep' and 'acpi-processor' 2017-02-20 14:28:03 +01:00
asm-generic kprobes: move kprobe declarations to asm-generic/kprobes.h 2017-02-27 18:43:45 -08:00
clocksource
crypto crypto: algapi - make crypto_xor() and crypto_inc() alignment agnostic 2017-02-11 17:52:28 +08:00
drm Less anger inducing pull request for 4.11 2017-02-23 18:58:18 -08:00
dt-bindings The usual collection of new drivers, non-critical fixes, and updates 2017-02-25 14:28:06 -08:00
keys KEYS: Differentiate uses of rcu_dereference_key() and user_key_payload() 2017-03-02 10:09:00 +11:00
kvm KVM: arm/arm64: Emulate the EL1 phys timer registers 2017-02-08 15:13:37 +00:00
linux KEYS: Differentiate uses of rcu_dereference_key() and user_key_payload() 2017-03-02 10:09:00 +11:00
math-emu
media scripts/spelling.txt: add "an union" pattern and fix typo instances 2017-02-27 18:43:46 -08:00
memory
misc
net scripts/spelling.txt: add "disassocation" pattern and fix typo instances 2017-02-27 18:43:47 -08:00
pcmcia
ras
rdma Merge branch 'for-4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 2017-02-27 21:41:08 -08:00
rxrpc
scsi SCSI misc on 20170220 2017-02-21 11:51:42 -08:00
soc ARC updates for 4.11 rc1 2017-02-22 10:33:53 -08:00
sound treewide: Remove remaining executable attributes from source files 2017-02-25 12:12:50 -08:00
target First set of updates for 4.11 kernel merge window 2017-02-23 08:27:57 -08:00
trace This release has no new tracing features, just clean ups, minor fixes 2017-02-27 13:26:17 -08:00
uapi The nfsd update this round is mainly a lot of miscellaneous cleanups and 2017-02-28 15:39:09 -08:00
video drm/exynos/decon5433: signal vblank only on odd fields 2017-02-07 13:52:52 +09:00
xen scripts/spelling.txt: add "an union" pattern and fix typo instances 2017-02-27 18:43:46 -08:00
Kbuild