[GIT PULL] kallsyms_show_value-fix updates for v5.9-rc1

[Kees Cook <keescook@chromium.org>]

Hi Linus,

Please pull this fix to my kallsyms_show_value() refactoring for
v5.9-rc1. About a month after the original refactoring landed, 0day
noticed that there was a path through the kernfs binattr read handlers
that did not have PAGE_SIZEd buffers, and the module "sections" read
handler made a bad assumption about this, resulting in it stomping on
memory when reached through small-sized splice() calls. I've added a set
of tests to find these kinds of regressions more quickly in the future
as well.

Thanks!

-Kees

The following changes since commit bcf876870b95592b52519ed4aafcf9d95999bc9c:

  Linux 5.8 (2020-08-02 14:21:45 -0700)

are available in the Git repository at:

  https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git tags/kallsyms_show_value-fix-v5.9-rc1

for you to fetch changes up to 9af47666cb0f331bfcd76799ee368cdfcb00882c:

  selftests: splice: Check behavior of full and short splices (2020-08-07 10:50:11 -0700)

----------------------------------------------------------------
Fix sysfs module section output overflow

----------------------------------------------------------------
Kees Cook (2):
      module: Correctly truncate sysfs sections output
      selftests: splice: Check behavior of full and short splices

 kernel/module.c                                    | 22 +++++++--
 tools/testing/selftests/splice/.gitignore          |  1 +
 tools/testing/selftests/splice/Makefile            |  4 +-
 tools/testing/selftests/splice/config              |  1 +
 tools/testing/selftests/splice/settings            |  1 +
 .../testing/selftests/splice/short_splice_read.sh  | 56 +++++++++++++++++++++
 tools/testing/selftests/splice/splice_read.c       | 57 ++++++++++++++++++++++
 7 files changed, 137 insertions(+), 5 deletions(-)
 create mode 100644 tools/testing/selftests/splice/config
 create mode 100644 tools/testing/selftests/splice/settings
 create mode 100755 tools/testing/selftests/splice/short_splice_read.sh
 create mode 100644 tools/testing/selftests/splice/splice_read.c

-- 
Kees Cook