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David Howells 660625922b afs: Fix server record deletion
AFS server records get removed from the net->fs_servers tree when
they're deleted, but not from the net->fs_addresses{4,6} lists, which
can lead to an oops in afs_find_server() when a server record has been
removed, for instance during rmmod.

Fix this by deleting the record from the by-address lists before posting
it for RCU destruction.

The reason this hasn't been noticed before is that the fileserver keeps
probing the local cache manager, thereby keeping the service record
alive, so the oops would only happen when a fileserver eventually gets
bored and stops pinging or if the module gets rmmod'd and a call comes
in from the fileserver during the window between the server records
being destroyed and the socket being closed.

The oops looks something like:

  BUG: unable to handle kernel NULL pointer dereference at 000000000000001c
  ...
  Workqueue: kafsd afs_process_async_call [kafs]
  RIP: 0010:afs_find_server+0x271/0x36f [kafs]
  ...
  Call Trace:
   afs_deliver_cb_init_call_back_state3+0x1f2/0x21f [kafs]
   afs_deliver_to_call+0x1ee/0x5e8 [kafs]
   afs_process_async_call+0x5b/0xd0 [kafs]
   process_one_work+0x2c2/0x504
   worker_thread+0x1d4/0x2ac
   kthread+0x11f/0x127
   ret_from_fork+0x24/0x30

Fixes: d2ddc776a4 ("afs: Overhaul volume and server record caching and fileserver rotation")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-20 09:59:33 -07:00
arch Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-04-20 09:15:14 -07:00
block blk-mq: Revert "blk-mq: reimplement blk_mq_hw_queue_mapped" 2018-04-11 07:59:15 -06:00
certs certs/blacklist_nohashes.c: fix const confusion in certs blacklist 2018-02-21 15:35:43 -08:00
crypto Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-04-20 09:34:39 -07:00
drivers Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-04-20 09:34:39 -07:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs afs: Fix server record deletion 2018-04-20 09:59:33 -07:00
include Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-04-20 09:34:39 -07:00
init Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-15 16:12:35 -07:00
ipc ipc/shm: fix use-after-free of shm file via remap_file_pages() 2018-04-13 17:10:27 -07:00
kernel Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching 2018-04-20 08:51:55 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-04-20 09:34:39 -07:00
LICENSES LICENSES: Add MPL-1.1 license 2018-01-06 10:59:44 -07:00
mm mm,vmscan: Allow preallocating memory for register_shrinker(). 2018-04-16 02:06:47 -04:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-04-20 09:34:39 -07:00
samples Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching 2018-04-20 08:51:55 -07:00
scripts Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
security + Features 2018-04-13 15:38:53 -07:00
sound amdgpu, omap and snd regression fix 2018-04-12 20:56:10 -07:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-04-20 09:34:39 -07:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt KVM/ARM updates for v4.17 2018-03-28 16:09:09 +02:00
.clang-format clang-format: add configuration file 2018-04-11 10:28:35 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge candidates for 4.17 merge window 2018-04-06 17:35:43 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE 2018-03-05 16:34:24 +00:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-04-20 09:34:39 -07:00
Makefile Linux 4.17-rc1 2018-04-15 18:24:20 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.