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Filename Latest commit message Latest commit date
Joe Lawrence 7a8d181949 pipe: add proc_dopipe_max_size() to safely assign pipe_max_size
pipe_max_size is assigned directly via procfs sysctl:

  static struct ctl_table fs_table[] = {
          ...
          {
                  .procname       = "pipe-max-size",
                  .data           = &pipe_max_size,
                  .maxlen         = sizeof(int),
                  .mode           = 0644,
                  .proc_handler   = &pipe_proc_fn,
                  .extra1         = &pipe_min_size,
          },
          ...

  int pipe_proc_fn(struct ctl_table *table, int write, void __user *buf,
                   size_t *lenp, loff_t *ppos)
  {
          ...
          ret = proc_dointvec_minmax(table, write, buf, lenp, ppos)
          ...

and then later rounded in-place a few statements later:

          ...
          pipe_max_size = round_pipe_size(pipe_max_size);
          ...

This leaves a window of time between initial assignment and rounding
that may be visible to other threads.  (For example, one thread sets a
non-rounded value to pipe_max_size while another reads its value.)

Similar reads of pipe_max_size are potentially racy:

  pipe.c :: alloc_pipe_info()
  pipe.c :: pipe_set_size()

Add a new proc_dopipe_max_size() that consolidates reading the new value
from the user buffer, verifying bounds, and calling round_pipe_size()
with a single assignment to pipe_max_size.

Link: http://lkml.kernel.org/r/1507658689-11669-4-git-send-email-joe.lawrence@redhat.com
Signed-off-by: Joe Lawrence <joe.lawrence@redhat.com>
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-17 16:10:03 -08:00
arch bug: define the "cut here" string in a single place 2017-11-17 16:10:01 -08:00
block
certs
crypto
Documentation dynamic_debug documentation: minor fixes 2017-11-17 16:10:01 -08:00
drivers lkdtm: include WARN format string 2017-11-17 16:10:01 -08:00
firmware
fs pipe: add proc_dopipe_max_size() to safely assign pipe_max_size 2017-11-17 16:10:03 -08:00
include pipe: add proc_dopipe_max_size() to safely assign pipe_max_size 2017-11-17 16:10:03 -08:00
init init/version.c: include <linux/export.h> instead of <linux/module.h> 2017-11-17 16:10:02 -08:00
ipc
kernel pipe: add proc_dopipe_max_size() to safely assign pipe_max_size 2017-11-17 16:10:03 -08:00
lib lib: test module for find_*_bit() functions 2017-11-17 16:10:02 -08:00
mm mm, compaction: remove unneeded pageblock_skip_persistent() checks 2017-11-17 16:10:00 -08:00
net
samples
scripts checkpatch: do not check missing blank line before builtin_*_driver 2017-11-17 16:10:02 -08:00
security
sound
tools tools/lib/traceevent/parse-filter.c: clean up clang build warning 2017-11-17 16:10:02 -08:00
usr
virt First batch of KVM changes for 4.15 2017-11-16 13:00:24 -08:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap Add Jason Gunthorpe as co-maintainer of the RDMA stack 2017-11-17 09:36:18 -08:00
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS libnvdimm for 4.15 2017-11-17 09:51:57 -08:00
Makefile
README

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.