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David Howells 29f0698532 afs: Fix AFS read bug
Fix a bug in AFS read whereby the request page afs_read::index isn't
incremented after calling ->page_done() if ->remain reaches 0, indicating
that the data read is complete.

Without this a NULL pointer exception happens when ->page_done() is called
twice for the last page because the page clearing loop will call it also
and afs_readpages_page_done() clears the current entry in the page list.

BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: afs_readpages_page_done+0x21/0xa4 [kafs]
PGD 0
Oops: 0002 [#1] SMP
Modules linked in: kafs(E)
CPU: 2 PID: 3002 Comm: md5sum Tainted: G            E   4.10.0-fscache #485
Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014
task: ffff8804017d86c0 task.stack: ffff8803fc1d8000
RIP: 0010:afs_readpages_page_done+0x21/0xa4 [kafs]
RSP: 0018:ffff8803fc1db978 EFLAGS: 00010282
RAX: ffff880405d39af8 RBX: 0000000000000000 RCX: ffff880407d83ed4
RDX: 0000000000000000 RSI: ffff880405d39a00 RDI: ffff880405c6f400
RBP: ffff8803fc1db988 R08: 0000000000000000 R09: 0000000000000001
R10: ffff8803fc1db820 R11: ffff88040cf56000 R12: ffff8804088f1780
R13: ffff8804017d86c0 R14: ffff8804088f1780 R15: 0000000000003840
FS:  00007f8154469700(0000) GS:ffff88041fb00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000004016ec000 CR4: 00000000001406e0
Call Trace:
 afs_deliver_fs_fetch_data+0x5b9/0x60e [kafs]
 ? afs_make_call+0x316/0x4e8 [kafs]
 ? afs_make_call+0x359/0x4e8 [kafs]
 afs_deliver_to_call+0x173/0x2e8 [kafs]
 ? afs_make_call+0x316/0x4e8 [kafs]
 afs_make_call+0x37a/0x4e8 [kafs]
 ? wake_up_q+0x4f/0x4f
 ? __init_waitqueue_head+0x36/0x49
 afs_fs_fetch_data+0x21c/0x227 [kafs]
 ? afs_fs_fetch_data+0x21c/0x227 [kafs]
 afs_vnode_fetch_data+0xf3/0x1d2 [kafs]
 afs_readpages+0x314/0x3fd [kafs]
 __do_page_cache_readahead+0x208/0x2c5
 ondemand_readahead+0x3a2/0x3b7
 ? ondemand_readahead+0x3a2/0x3b7
 page_cache_async_readahead+0x5e/0x67
 generic_file_read_iter+0x23b/0x70c
 ? __inode_security_revalidate+0x2f/0x62
 __vfs_read+0xc4/0xe8
 vfs_read+0xd1/0x15a
 SyS_read+0x4c/0x89
 do_syscall_64+0x80/0x191
 entry_SYSCALL64_slow_path+0x25/0x25

Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marc Dionne <marc.dionne@auristor.com>
2017-03-16 16:27:46 +00:00
arch Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2017-03-15 09:26:04 -07:00
block blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly() 2017-03-14 11:51:59 -06:00
certs certs: Add a secondary system keyring that can be added to dynamically 2016-04-11 22:48:09 +01:00
crypto net: Work around lockdep limitation in sockets that use sockets 2017-03-09 18:23:27 -08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-03-14 21:31:23 -07:00
drivers Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-03-15 16:54:58 -07:00
firmware WHENCE: use https://linuxtv.org for LinuxTV URLs 2015-12-04 10:35:11 -02:00
fs afs: Fix AFS read bug 2017-03-16 16:27:46 +00:00
include SCSI fixes on 20170315 2017-03-15 10:44:19 -07:00
init Change get_random_{int,log} to use the CRNG used by /dev/urandom and 2017-03-11 09:08:47 -08:00
ipc Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-03-14 21:31:23 -07:00
lib mm: convert generic code to 5-level paging 2017-03-09 11:48:47 -08:00
mm Merge branch 'for-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu 2017-03-14 14:48:50 -07:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-03-14 21:31:23 -07:00
samples Merge branch 'rebased-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-03-03 11:38:56 -08:00
scripts Merge branch 'akpm' (patches from Andrew) 2017-03-10 08:34:42 -08:00
security Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
sound scripts/spelling.txt: add "disble(d)" pattern and fix typo instances 2017-03-09 17:01:09 -08:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-03-14 21:31:23 -07:00
usr kbuild: initramfs cleanup, set target from Kconfig 2017-01-05 09:40:16 -08:00
virt KVM: arm/arm64: VGIC: Fix command handling while ITS being disabled 2017-03-07 15:44:08 +00:00
.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 Merge branch 'misc' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-08-02 16:48:52 -04:00
.mailmap mailmap: add codeaurora.org names for nameless email commits 2017-01-10 18:31:55 -08:00
COPYING
CREDITS MAINTAINERS: Remove old e-mail address 2017-02-13 12:24:56 -05:00
Kbuild scripts/gdb: provide linux constants 2016-05-23 17:04:14 -07:00
Kconfig
MAINTAINERS MAINTAINERS: usb251xb: remove reference inexistent file 2017-03-09 10:34:16 +01:00
Makefile Linux 4.11-rc2 2017-03-12 14:47:08 -07:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

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.