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David Howells b537a3c217 afs: Fix corruption in reads at fpos 2G-4G from an OpenAFS server
AFS-3 has two data fetch RPC variants, FS.FetchData and FS.FetchData64, and
Linux's afs client switches between them when talking to a non-YFS server
if the read size, the file position or the sum of the two have the upper 32
bits set of the 64-bit value.

This is a problem, however, since the file position and length fields of
FS.FetchData are *signed* 32-bit values.

Fix this by capturing the capability bits obtained from the fileserver when
it's sent an FS.GetCapabilities RPC, rather than just discarding them, and
then picking out the VICED_CAPABILITY_64BITFILES flag.  This can then be
used to decide whether to use FS.FetchData or FS.FetchData64 - and also
FS.StoreData or FS.StoreData64 - rather than using upper_32_bits() to
switch on the parameter values.

This capabilities flag could also be used to limit the maximum size of the
file, but all servers must be checked for that.

Note that the issue does not exist with FS.StoreData - that uses *unsigned*
32-bit values.  It's also not a problem with Auristor servers as its
YFS.FetchData64 op uses unsigned 64-bit values.

This can be tested by cloning a git repo through an OpenAFS client to an
OpenAFS server and then doing "git status" on it from a Linux afs
client[1].  Provided the clone has a pack file that's in the 2G-4G range,
the git status will show errors like:

	error: packfile .git/objects/pack/pack-5e813c51d12b6847bbc0fcd97c2bca66da50079c.pack does not match index
	error: packfile .git/objects/pack/pack-5e813c51d12b6847bbc0fcd97c2bca66da50079c.pack does not match index

This can be observed in the server's FileLog with something like the
following appearing:

Sun Aug 29 19:31:39 2021 SRXAFS_FetchData, Fid = 2303380852.491776.3263114, Host 192.168.11.201:7001, Id 1001
Sun Aug 29 19:31:39 2021 CheckRights: len=0, for host=192.168.11.201:7001
Sun Aug 29 19:31:39 2021 FetchData_RXStyle: Pos 18446744071815340032, Len 3154
Sun Aug 29 19:31:39 2021 FetchData_RXStyle: file size 2400758866
...
Sun Aug 29 19:31:40 2021 SRXAFS_FetchData returns 5

Note the file position of 18446744071815340032.  This is the requested file
position sign-extended.

Fixes: b9b1f8d593 ("AFS: write support fixes")
Reported-by: Markus Suvanto <markus.suvanto@gmail.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
Tested-by: Markus Suvanto <markus.suvanto@gmail.com>
cc: linux-afs@lists.infradead.org
cc: openafs-devel@openafs.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=214217#c9 [1]
Link: https://lore.kernel.org/r/951332.1631308745@warthog.procyon.org.uk/
2021-09-13 09:14:21 +01:00
arch for-5.15/block-2021-08-30 2021-08-30 18:52:11 -07:00
block io_uring-bio-cache.5-2021-08-30 2021-08-30 19:30:30 -07:00
certs certs: Add support for using elliptic curve keys for signing modules 2021-08-23 19:55:42 +03:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2021-08-30 12:57:10 -07:00
Documentation for-5.15/libata-2021-08-30 2021-08-30 19:09:45 -07:00
drivers for-5.15/libata-2021-08-30 2021-08-30 19:09:45 -07:00
fs afs: Fix corruption in reads at fpos 2G-4G from an OpenAFS server 2021-09-13 09:14:21 +01:00
include afs: Try to avoid taking RCU read lock when checking vnode validity 2021-09-13 09:10:39 +01:00
init for-5.15/block-2021-08-30 2021-08-30 18:52:11 -07:00
ipc Merge branch 'akpm' (patches from Andrew) 2021-07-02 12:08:10 -07:00
kernel for-5.15/io_uring-2021-08-30 2021-08-30 19:22:52 -07:00
lib for-5.15/block-2021-08-30 2021-08-30 18:52:11 -07:00
LICENSES LICENSES/dual/CC-BY-4.0: Git rid of "smart quotes" 2021-07-15 06:31:24 -06:00
mm afs: Fix mmap coherency vs 3rd-party changes 2021-09-13 09:10:39 +01:00
net for-5.15/io_uring-2021-08-30 2021-08-30 19:22:52 -07:00
samples Networking fixes for 5.14-rc2, including fixes from bpf and netfilter. 2021-07-14 09:24:32 -07:00
scripts Linux 5.14-rc6 2021-08-17 16:16:29 +02:00
security A handful of EFI changes for this cycle: 2021-08-30 13:57:55 -07:00
sound another sound-fixes for 5.14-rc7 2021-08-20 12:31:10 -07:00
tools Merge branch 'core-rcu.2021.08.28a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu 2021-08-30 12:48:01 -07:00
usr .gitignore: prefix local generated files with a slash 2021-05-02 00:43:35 +09:00
virt KVM: Do not leak memory for duplicate debugfs directories 2021-08-04 06:02:03 -04:00
.clang-format clang-format: Update with the latest for_each macro list 2021-05-12 23:32:39 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap m68k updates for v5.14 2021-06-28 14:01:03 -07:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: move Murali Karicheri to credits 2021-04-29 15:47:30 -07:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS for-5.15/drivers-2021-08-30 2021-08-30 19:01:46 -07:00
Makefile Linux 5.14 2021-08-29 15:04:50 -07:00
README

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.

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.