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Christian Brauner 32a5ad9c22 sysctl: handle overflow for file-max
Currently, when writing

  echo 18446744073709551616 > /proc/sys/fs/file-max

/proc/sys/fs/file-max will overflow and be set to 0.  That quickly
crashes the system.

This commit sets the max and min value for file-max.  The max value is
set to long int.  Any higher value cannot currently be used as the
percpu counters are long ints and not unsigned integers.

Note that the file-max value is ultimately parsed via
__do_proc_doulongvec_minmax().  This function does not report error when
min or max are exceeded.  Which means if a value largen that long int is
written userspace will not receive an error instead the old value will be
kept.  There is an argument to be made that this should be changed and
__do_proc_doulongvec_minmax() should return an error when a dedicated min
or max value are exceeded.  However this has the potential to break
userspace so let's defer this to an RFC patch.

Link: http://lkml.kernel.org/r/20190107222700.15954-3-christian@brauner.io
Signed-off-by: Christian Brauner <christian@brauner.io>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Dominik Brodowski <linux@dominikbrodowski.net>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Waiman Long <longman@redhat.com>
[christian@brauner.io: v4]
  Link: http://lkml.kernel.org/r/20190210203943.8227-3-christian@brauner.io
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-03-07 18:32:02 -08:00
arch
block
certs
crypto
Documentation USB/PHY patches for 5.1-rc1 2019-03-06 16:48:27 -08:00
drivers rapidio/mport_cdev: mark expected switch fall-through 2019-03-07 18:32:02 -08:00
fs exec: increase BINPRM_BUF_SIZE to 256 2019-03-07 18:32:01 -08:00
include exec: increase BINPRM_BUF_SIZE to 256 2019-03-07 18:32:01 -08:00
init
ipc
kernel sysctl: handle overflow for file-max 2019-03-07 18:32:02 -08:00
lib lib/test_firmware.c: remove some dead code 2019-03-07 18:32:00 -08:00
LICENSES
mm
net
samples
scripts checkpatch: add test for SPDX-License-Identifier on wrong line # 2019-03-07 18:32:01 -08:00
security
sound
tools Staging/IIO patches for 5.1-rc1 2019-03-06 16:29:27 -08:00
usr
virt
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
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MAINTAINERS USB/PHY patches for 5.1-rc1 2019-03-06 16:48:27 -08:00
Makefile
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.