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David Howells cf65b5bfac vfs: Check the truncate maximum size in inode_newsize_ok() 
commit e2ebff9c57 upstream.

If something manages to set the maximum file size to MAX_OFFSET+1, this
can cause the xfs and ext4 filesystems at least to become corrupt.

Ordinarily, the kernel protects against userspace trying this by
checking the value early in the truncate() and ftruncate() system calls
calls - but there are at least two places that this check is bypassed:

 (1) Cachefiles will round up the EOF of the backing file to DIO block
     size so as to allow DIO on the final block - but this might push
     the offset negative. It then calls notify_change(), but this
     inadvertently bypasses the checking. This can be triggered if
     someone puts an 8EiB-1 file on a server for someone else to try and
     access by, say, nfs.

 (2) ksmbd doesn't check the value it is given in set_end_of_file_info()
     and then calls vfs_truncate() directly - which also bypasses the
     check.

In both cases, it is potentially possible for a network filesystem to
cause a disk filesystem to be corrupted: cachefiles in the client's
cache filesystem; ksmbd in the server's filesystem.

nfsd is okay as it checks the value, but we can then remove this check
too.

Fix this by adding a check to inode_newsize_ok(), as called from
setattr_prepare(), thereby catching the issue as filesystems set up to
perform the truncate with minimal opportunity for bypassing the new
check.

Fixes: 1f08c925e7 ("cachefiles: Implement backing file wrangling")
Fixes: f441584858 ("cifsd: add file operations")
Signed-off-by: David Howells <dhowells@redhat.com>
Reported-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Cc: stable@kernel.org
Acked-by: Alexander Viro <viro@zeniv.linux.org.uk>
cc: Steve French <sfrench@samba.org>
cc: Hyunchul Lee <hyc.lee@gmail.com>
cc: Chuck Lever <chuck.lever@oracle.com>
cc: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-08-21 15:15:22 +02:00
arch riscv: set default pm_power_off to NULL 2022-08-21 15:15:21 +02:00
block block: Fix handling of offline queues in blk_mq_alloc_request_hctx() 2022-06-22 14:13:17 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:13:17 +02:00
crypto crypto: memneq - move into lib/ 2022-06-22 14:13:18 +02:00
Documentation x86/speculation: Add RSB VM Exit protections 2022-08-11 13:06:47 +02:00
drivers tty: vt: initialize unicode screen buffer 2022-08-21 15:15:22 +02:00
fs vfs: Check the truncate maximum size in inode_newsize_ok() 2022-08-21 15:15:22 +02:00
include mm: Add kvrealloc() 2022-08-21 15:15:21 +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 watch_queue: Fix missing locking in add_watch_to_object() 2022-08-03 12:00:44 +02:00
lib ida: don't use BUG_ON() for debugging 2022-07-12 16:32:23 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm/mremap: hold the rmap lock in write mode when moving page table entries. 2022-08-21 15:15:21 +02:00
net bpf: Add PROG_TEST_RUN support for sk_lookup programs 2022-08-03 12:00:52 +02:00
samples x86: Prepare inline-asm for straight-line-speculation 2022-07-25 11:26:29 +02:00
scripts x86/retbleed: Add fine grained Kconfig knobs 2022-07-25 11:26:50 +02:00
security lockdown: Fix kexec lockdown bypass with ima policy 2022-07-29 17:19:06 +02:00
sound ALSA: hda/realtek: Add a quirk for HP OMEN 15 (8786) mute LED 2022-08-21 15:15:22 +02:00
tools x86/speculation: Add RSB VM Exit protections 2022-08-11 13:06:47 +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: Don't null dereference ops->destroy 2022-07-29 17:19:23 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.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 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 COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
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 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 Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.