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Tyler Hicks 5a2a00b604 net/9p: Initialize the iounit field during fid creation
commit aa7aeee169 upstream.

Ensure that the fid's iounit field is set to zero when a new fid is
created. Certain 9P operations, such as OPEN and CREATE, allow the
server to reply with an iounit size which the client code assigns to the
p9_fid struct shortly after the fid is created by p9_fid_create(). On
the other hand, an XATTRWALK operation doesn't allow for the server to
specify an iounit value. The iounit field of the newly allocated p9_fid
struct remained uninitialized in that case. Depending on allocation
patterns, the iounit value could have been something reasonable that was
carried over from previously freed fids or, in the worst case, could
have been arbitrary values from non-fid related usages of the memory
location.

The bug was detected in the Windows Subsystem for Linux 2 (WSL2) kernel
after the uninitialized iounit field resulted in the typical sequence of
two getxattr(2) syscalls, one to get the size of an xattr and another
after allocating a sufficiently sized buffer to fit the xattr value, to
hit an unexpected ERANGE error in the second call to getxattr(2). An
uninitialized iounit field would sometimes force rsize to be smaller
than the xattr value size in p9_client_read_once() and the 9P server in
WSL refused to chunk up the READ on the attr_fid and, instead, returned
ERANGE to the client. The virtfs server in QEMU seems happy to chunk up
the READ and this problem goes undetected there.

Link: https://lkml.kernel.org/r/20220710141402.803295-1-tyhicks@linux.microsoft.com
Fixes: ebf46264a0 ("fs/9p: Add support user. xattr")
Cc: stable@vger.kernel.org
Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Reviewed-by: Christian Schoenebeck <linux_oss@crudebyte.com>
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
[tyhicks: Adjusted context due to:
 - Lack of fid refcounting introduced in v5.11 commit 6636b6dcc3 ("9p:
   add refcount to p9_fid struct")
 - Difference in how buffer sizes are specified v5.16 commit
   6e195b0f7c ("9p: fix a bunch of checkpatch warnings")]
Signed-off-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-08-21 15:16:26 +02:00
arch kvm: x86/pmu: Fix the compare function used by the pmu event filter 2022-08-21 15:16:26 +02:00
block block: remove the request_queue to argument request based tracepoints 2022-08-21 15:15:36 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:13:17 +02:00
crypto KEYS: asymmetric: enforce SM2 signature use pkey algo 2022-08-21 15:16:22 +02:00
Documentation xen-blkfront: Apply 'feature_persistent' parameter when connect 2022-08-21 15:16:22 +02:00
drivers tee: add overflow check in register_shm_helper() 2022-08-21 15:16:26 +02:00
fs ext4: correct the misjudgment in ext4_iget_extra_inode 2022-08-21 15:16:24 +02:00
include KVM: Add infrastructure and macro to mark VM as bugged 2022-08-21 15:16:24 +02:00
init Kconfig: Add option for asm goto w/ tied outputs to workaround clang-13 bug 2022-06-09 10:21:25 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-09 10:21:17 +02:00
kernel timekeeping: contribute wall clock to rng on time change 2022-08-21 15:16:20 +02:00
lib lib/smp_processor_id: fix imbalanced instrumentation_end() call 2022-08-21 15:16:08 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm/mmap.c: fix missing call to vm_unacct_memory in mmap_region 2022-08-21 15:16:02 +02:00
net net/9p: Initialize the iounit field during fid creation 2022-08-21 15:16:26 +02:00
samples x86: Prepare inline-asm for straight-line-speculation 2022-07-25 11:26:29 +02:00
scripts scripts/faddr2line: Fix vmlinux detection on arm64 2022-08-21 15:16:12 +02:00
security selinux: Add boundary check in put_entry() 2022-08-21 15:15:31 +02:00
sound ASoC: mchp-spdifrx: disable end of block interrupt on failures 2022-08-21 15:16:10 +02:00
tools tools/thermal: Fix possible path truncations 2022-08-21 15:16:12 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:25:48 +01:00
virt KVM: Add infrastructure and macro to mark VM as bugged 2022-08-21 15:16:24 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add Amir as xfs maintainer for 5.10.y 2022-07-02 16:39:22 +02:00
Makefile Makefile: link with -z noexecstack --no-warn-rwx-segments 2022-08-21 15:15:18 +02:00
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.