path: root/mm/Kconfig.debug
diff options
authorLaura Abbott <>2016-03-15 14:56:27 -0700
committerLinus Torvalds <>2016-03-15 16:55:16 -0700
commit8823b1dbc05fab1a8bec275eeae4709257c2661d (patch)
treea7d6683189c1656ac0879a0a7e9f39c695abfeee /mm/Kconfig.debug
parentff8e81163889ac4c7f59e7f7db6377d0c5d8d69c (diff)
mm/page_poison.c: enable PAGE_POISONING as a separate option
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 Signed-off-by: Laura Abbott <> Cc: Rafael J. Wysocki <> Cc: "Kirill A. Shutemov" <> Cc: Vlastimil Babka <> Cc: Michal Hocko <> Cc: Kees Cook <> Cc: Mathias Krause <> Cc: Dave Hansen <> Cc: Jianyu Zhan <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'mm/Kconfig.debug')
1 files changed, 24 insertions, 1 deletions
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index a0c136af9c91..1f99f9a0deae 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -41,4 +41,27 @@ config DEBUG_PAGEALLOC_ENABLE_DEFAULT
can be overridden by debug_pagealloc=off|on.
- bool
+ bool "Poison pages after freeing"
+ ---help---
+ Fill the pages with poison patterns after free_pages() and verify
+ the patterns before alloc_pages. The filling of the memory helps
+ reduce the risk of information leaks from freed data. This does
+ have a potential performance impact.
+ Note that "poison" here is not the same thing as the "HWPoison"
+ for CONFIG_MEMORY_FAILURE. This is software poisoning only.
+ If unsure, say N
+ depends on PAGE_POISONING
+ bool "Only poison, don't sanity check"
+ ---help---
+ Skip the sanity checking on alloc, only fill the pages with
+ poison on free. This reduces some of the overhead of the
+ poisoning feature.
+ If you are only interested in sanitization, say Y. Otherwise
+ say N.