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| author | Kees Cook <keescook@chromium.org> | 2017-12-01 13:19:39 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-12-18 15:59:17 +0100 |
| commit | 22ec1a2aea73b9dfe340dff7945bd85af4cc6280 (patch) | |
| tree | 92c1a38f121417e5702fe1f41ef99ea1004273ae /security/Kconfig | |
| parent | d9cc5a0edb705ced4ce91b4c6ee73ec6f5bfa49a (diff) | |
| download | lwn-22ec1a2aea73b9dfe340dff7945bd85af4cc6280.tar.gz lwn-22ec1a2aea73b9dfe340dff7945bd85af4cc6280.zip | |
/dev/mem: Add bounce buffer for copy-out
As done for /proc/kcore in
commit df04abfd181a ("fs/proc/kcore.c: Add bounce buffer for ktext data")
this adds a bounce buffer when reading memory via /dev/mem. This
is needed to allow kernel text memory to be read out when built with
CONFIG_HARDENED_USERCOPY (which refuses to read out kernel text) and
without CONFIG_STRICT_DEVMEM (which would have refused to read any RAM
contents at all).
Since this build configuration isn't common (most systems with
CONFIG_HARDENED_USERCOPY also have CONFIG_STRICT_DEVMEM), this also tries
to inform Kconfig about the recommended settings.
This patch is modified from Brad Spengler/PaX Team's changes to /dev/mem
code in the last public patch of grsecurity/PaX based on my understanding
of the code. Changes or omissions from the original code are mine and
don't reflect the original grsecurity/PaX code.
Reported-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Fixes: f5509cc18daa ("mm: Hardened usercopy")
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'security/Kconfig')
| -rw-r--r-- | security/Kconfig | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/security/Kconfig b/security/Kconfig index e8e449444e65..3b4effd8bbc2 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -143,6 +143,7 @@ config HARDENED_USERCOPY bool "Harden memory copies between kernel and userspace" depends on HAVE_HARDENED_USERCOPY_ALLOCATOR select BUG + imply STRICT_DEVMEM help This option checks for obviously wrong memory regions when copying memory to/from the kernel (via copy_to_user() and |