linux-stable.git/net/sunrpc, branch v3.0.22

svcrpc: avoid memory-corruption on pool shutdown

2012-01-26T01:24:48+00:00

commit b4f36f88b3ee7cf26bf0be84e6c7fc15f84dcb71 upstream.

Socket callbacks use svc_xprt_enqueue() to add an xprt to a
pool->sp_sockets list.  In normal operation a server thread will later
come along and take the xprt off that list.  On shutdown, after all the
threads have exited, we instead manually walk the sv_tempsocks and
sv_permsocks lists to find all the xprt's and delete them.

So the sp_sockets lists don't really matter any more.  As a result,
we've mostly just ignored them and hoped they would go away.

Which has gotten us into trouble; witness for example ebc63e531cc6
"svcrpc: fix list-corrupting race on nfsd shutdown", the result of Ben
Greear noticing that a still-running svc_xprt_enqueue() could re-add an
xprt to an sp_sockets list just before it was deleted.  The fix was to
remove it from the list at the end of svc_delete_xprt().  But that only
made corruption less likely--I can see nothing that prevents a
svc_xprt_enqueue() from adding another xprt to the list at the same
moment that we're removing this xprt from the list.  In fact, despite
the earlier xpo_detach(), I don't even see what guarantees that
svc_xprt_enqueue() couldn't still be running on this xprt.

So, instead, note that svc_xprt_enqueue() essentially does:
	lock sp_lock
		if XPT_BUSY unset
			add to sp_sockets
	unlock sp_lock

So, if we do:

	set XPT_BUSY on every xprt.
	Empty every sp_sockets list, under the sp_socks locks.

Then we're left knowing that the sp_sockets lists are all empty and will
stay that way, since any svc_xprt_enqueue() will check XPT_BUSY under
the sp_lock and see it set.

And *then* we can continue deleting the xprt's.

(Thanks to Jeff Layton for being correctly suspicious of this code....)

Cc: Ben Greear 
Cc: Jeff Layton 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Greg Kroah-Hartman

svcrpc: destroy server sockets all at once

2012-01-26T01:24:48+00:00

commit 2fefb8a09e7ed251ae8996e0c69066e74c5aa560 upstream.

There's no reason I can see that we need to call sv_shutdown between
closing the two lists of sockets.

Signed-off-by: J. Bruce Fields 
Signed-off-by: Greg Kroah-Hartman

svcrpc: fix double-free on shutdown of nfsd after changing pool mode

2012-01-26T01:24:47+00:00

commit 61c8504c428edcebf23b97775a129c5b393a302b upstream.

The pool_to and to_pool fields of the global svc_pool_map are freed on
shutdown, but are initialized in nfsd startup only in the
SVC_POOL_PERCPU and SVC_POOL_PERNODE cases.

They *are* initialized to zero on kernel startup.  So as long as you use
only SVC_POOL_GLOBAL (the default), this will never be a problem.

You're also OK if you only ever use SVC_POOL_PERCPU or SVC_POOL_PERNODE.

However, the following sequence events leads to a double-free:

	1. set SVC_POOL_PERCPU or SVC_POOL_PERNODE
	2. start nfsd: both fields are initialized.
	3. shutdown nfsd: both fields are freed.
	4. set SVC_POOL_GLOBAL
	5. start nfsd: the fields are left untouched.
	6. shutdown nfsd: now we try to free them again.

Step 4 is actually unnecessary, since (for some bizarre reason), nfsd
automatically resets the pool mode to SVC_POOL_GLOBAL on shutdown.

Signed-off-by: J. Bruce Fields 
Signed-off-by: Greg Kroah-Hartman

SUNRPC: Ensure we return EAGAIN in xs_nospace if congestion is cleared

2011-12-09T16:52:27+00:00

commit 24ca9a847791fd53d9b217330b15f3c285827a18 upstream.

By returning '0' instead of 'EAGAIN' when the tests in xs_nospace() fail
to find evidence of socket congestion, we are making the RPC engine believe
that the message was incorrectly sent and so it disconnects the socket
instead of just retrying.

The bug appears to have been introduced by commit
5e3771ce2d6a69e10fcc870cdf226d121d868491 (SUNRPC: Ensure that xs_nospace
return values are propagated).

Reported-by: Andrew Cooper 
Signed-off-by: Trond Myklebust 
Tested-by: Andrew Cooper 
Signed-off-by: Greg Kroah-Hartman

NFS/sunrpc: don't use a credential with extra groups.

2011-11-11T17:37:07+00:00

commit dc6f55e9f8dac4b6479be67c5c9128ad37bb491f upstream.

The sunrpc layer keeps a cache of recently used credentials and
'unx_match' is used to find the credential which matches the current
process.

However unx_match allows a match when the cached credential has extra
groups at the end of uc_gids list which are not in the process group list.

So if a process with a list of (say) 4 group accesses a file and gains
access because of the last group in the list, then another process
with the same uid and gid, and a gid list being the first tree of the
gids of the original process tries to access the file, it will be
granted access even though it shouldn't as the wrong rpc credential
will be used.

Signed-off-by: NeilBrown 
Signed-off-by: Trond Myklebust 
Signed-off-by: Greg Kroah-Hartman

svcrpc: fix list-corrupting race on nfsd shutdown

2011-08-05T04:58:40+00:00

commit ebc63e531cc6a457595dd110b07ac530eae788c3 upstream.

After commit 3262c816a3d7fb1eaabce633caa317887ed549ae "[PATCH] knfsd:
split svc_serv into pools", svc_delete_xprt (then svc_delete_socket) no
longer removed its xpt_ready (then sk_ready) field from whatever list it
was on, noting that there was no point since the whole list was about to
be destroyed anyway.

That was mostly true, but forgot that a few svc_xprt_enqueue()'s might
still be hanging around playing with the about-to-be-destroyed list, and
could get themselves into trouble writing to freed memory if we left
this xprt on the list after freeing it.

(This is actually functionally identical to a patch made first by Ben
Greear, but with more comments.)

Cc: gnb@fmeh.org
Reported-by: Ben Greear 
Tested-by: Ben Greear 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Greg Kroah-Hartman

SUNRPC: Fix use of static variable in rpcb_getport_async

2011-07-12T17:40:13+00:00

Because struct rpcbind_args *map was declared static, if two
threads entered this method at the same time, the values
assigned to map could be sent two two differen tasks.
This could cause all sorts of problems, include use-after-free
and double-free of memory.

Fix this by removing the static declaration so that the map
pointer is on the stack.

Signed-off-by: Ben Greear 
Cc: stable@kernel.org
Signed-off-by: Trond Myklebust

SUNRPC: Fix a race between work-queue and rpc_killall_tasks

2011-07-08T00:45:37+00:00

Since rpc_killall_tasks may modify the rpc_task's tk_action field
without any locking, we need to be careful when dereferencing it.

Reported-by: Ben Greear 
Tested-by: Ben Greear 
Signed-off-by: Trond Myklebust 
Cc: stable@kernel.org

Merge branch 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6

2011-06-22T01:20:55+00:00

* 'bugfixes' of git://git.linux-nfs.org/projects/trondmy/nfs-2.6:
  NFS: Fix decode_secinfo_maxsz
  NFSv4.1: Fix an off-by-one error in pnfs_generic_pg_test
  NFSv4.1: Fix some issues with pnfs_generic_pg_test
  NFSv4.1: file layout must consider pg_bsize for coalescing
  pnfs-obj: No longer needed to take an extra ref at add_device
  SUNRPC: Ensure the RPC client only quits on fatal signals
  NFSv4: Fix a readdir regression
  nfs4.1: mark layout as bad on error path in _pnfs_return_layout
  nfs4.1: prevent race that allowed use of freed layout in _pnfs_return_layout
  NFSv4.1: need to put_layout_hdr on _pnfs_return_layout error path
  NFS: (d)printks should use %zd for ssize_t arguments
  NFSv4.1: fix break condition in pnfs_find_lseg
  nfs4.1: fix several problems with _pnfs_return_layout
  NFSv4.1: allow zero fh array in filelayout decode layout
  NFSv4.1: allow nfs_fhget to succeed with mounted on fileid
  NFSv4.1: Fix a refcounting issue in the pNFS device id cache
  NFSv4.1: deprecate headerpadsz in CREATE_SESSION
  NFS41: do not update isize if inode needs layoutcommit
  NLM: Don't hang forever on NLM unlock requests
  NFS: fix umount of pnfs filesystems

SUNRPC: Ensure the RPC client only quits on fatal signals

2011-06-17T14:17:19+00:00

Fix a couple of instances where we were exiting the RPC client on
arbitrary signals. We should only do so on fatal signals.

Cc: stable@kernel.org
Signed-off-by: Trond Myklebust