The patch titled
Subject: mm: clarify CONFIG_PAGE_POISONING and usage
has been added to the -mm tree. Its filename is
mm-clarify-config_page_poisoning-and-usage.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-clarify-config_page_poisoning-and-usage.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-clarify-config_page_poisoning-and-usage.patch
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------------------------------------------------------
From: Kees Cook <keescook@xxxxxxxxxxxx>
Subject: mm: clarify CONFIG_PAGE_POISONING and usage
The Kconfig text for CONFIG_PAGE_POISONING doesn't mention that it has to
be enabled explicitly. This updates the documentation for that and adds a
note about CONFIG_PAGE_POISONING to the "page_poison" command line docs.
While here, change description of CONFIG_PAGE_POISONING_ZERO too, as it's
not "random" data, but rather the fixed debugging value that would be used
when not zeroing. Additionally removes a stray "bool" in the Kconfig.
Link: http://lkml.kernel.org/r/20180725223832.GA43733@beast
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Laura Abbott <labbott@xxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN Documentation/admin-guide/kernel-parameters.txt~mm-clarify-config_page_poisoning-and-usage Documentation/admin-guide/kernel-parameters.txt
--- a/Documentation/admin-guide/kernel-parameters.txt~mm-clarify-config_page_poisoning-and-usage
+++ a/Documentation/admin-guide/kernel-parameters.txt
@@ -2933,8 +2933,9 @@
on: enable the feature
page_poison= [KNL] Boot-time parameter changing the state of
- poisoning on the buddy allocator.
- off: turn off poisoning
+ poisoning on the buddy allocator, available with
+ CONFIG_PAGE_POISONING=y.
+ off: turn off poisoning (default)
on: turn on poisoning
panic= [KNL] Kernel behaviour on panic: delay <timeout>
diff -puN mm/Kconfig.debug~mm-clarify-config_page_poisoning-and-usage mm/Kconfig.debug
--- a/mm/Kconfig.debug~mm-clarify-config_page_poisoning-and-usage
+++ a/mm/Kconfig.debug
@@ -46,7 +46,8 @@ config PAGE_POISONING
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.
+ have a potential performance impact if enabled with the
+ "page_poison=1" kernel boot option.
Note that "poison" here is not the same thing as the "HWPoison"
for CONFIG_MEMORY_FAILURE. This is software poisoning only.
@@ -65,7 +66,7 @@ config PAGE_POISONING_NO_SANITY
say N.
config PAGE_POISONING_ZERO
- bool "Use zero for poisoning instead of random data"
+ bool "Use zero for poisoning instead of debugging value"
depends on PAGE_POISONING
---help---
Instead of using the existing poison value, fill the pages with
@@ -75,7 +76,6 @@ config PAGE_POISONING_ZERO
allocation.
If unsure, say N
- bool
config DEBUG_PAGE_REF
bool "Enable tracepoint to track down page reference manipulation"
_
Patches currently in -mm which might be from keescook@xxxxxxxxxxxx are
ntfs-aops-remove-vla-usage.patch
ntfs-decompress-remove-vla-usage.patch
ntfs-mft-remove-vla-usage.patch
mm-clarify-config_page_poisoning-and-usage.patch
kernelh-documentation-for-roundup-vs-round_up.patch
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