Add a config option to enable page poisoning by
default. The kernel command line option "page_poison"
can be used to change the behaviour during boot.
Change-Id: Ie70763841191a722b1c6125dfad119a29ed0f605
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
On SPARSEMEM systems page poisoning is enabled after buddy is up, because
of the dependency on page extension init. This causes the pages released
by free_all_bootmem not to be poisoned. This either delays or misses the
identification of some issues because the pages have to undergo another
cycle of alloc-free-alloc for any corruption to be detected.
Enable page poisoning early by getting rid of the PAGE_EXT_DEBUG_POISON
flag. Since all the free pages will now be poisoned, the flag need not be
verified before checking the poison during an alloc.
Link: http://lkml.kernel.org/r/1490358246-11001-1-git-send-email-vinmenon@codeaurora.org
Acked-by: Laura Abbott <labbott@redhat.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
[vinmenon@codeaurora.org: resolve trivial merge conflicts.
Remove the redundant free pages RO feature from the
page_poison.c file which is the reason for conflicts +
squash the addendum commit 40961ef8d65f51093bc94de110b97b590b6b9275
('mm-enable-page-poisoning-early-at-boot-v2')]
Git-commit: c5b7cd344fd6341e6db79e55c0f1f4d1d9c67a7e
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
Change-Id: I1bb1f99d3a2e1135131911905e0916c837ba9d8a
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
By default, page poisoning uses a poison value (0xaa) on free. If this
is changed to 0, the page is not only sanitized but zeroing on alloc
with __GFP_ZERO can be skipped as well. The tradeoff is that detecting
corruption from the poisoning is harder to detect. This feature also
cannot be used with hibernation since pages are not guaranteed to be
zeroed after hibernation.
Credit to Grsecurity/PaX team for inspiring this work
Change-Id: If7116e6bff246abbafc38bdfeb3601d3ea063ad2
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Acked-by: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jianyu Zhan <nasa4836@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: 1414c7f4f7d72d138fff35f00151d15749b5beda
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
Page poisoning is currently set up as a feature if architectures don't
have architecture debug page_alloc to allow unmapping of pages. It has
uses apart from that though. Clearing of the pages on free provides an
increase in security as it helps to limit the risk of information leaks.
Allow page poisoning to be enabled as a separate option independent of
kernel_map pages since the two features do separate work. Because of
how hiberanation is implemented, the checks on alloc cannot occur if
hibernation is enabled. The runtime alloc checks can also be enabled
with an option when !HIBERNATION.
Credit to Grsecurity/PaX team for inspiring this work
Change-Id: I77a36f844ddae54695089c98a97bf0a6e226a025
Signed-off-by: Laura Abbott <labbott@fedoraproject.org>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Jianyu Zhan <nasa4836@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: 8823b1dbc05fab1a8bec275eeae4709257c2661d
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org>
