From: Kees Cook <keescook@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>,
Laura Abbott <labbott@redhat.com>,
linux-doc@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: [PATCH] mm: Clarify CONFIG_PAGE_POISONING and usage
Date: Wed, 25 Jul 2018 15:38:32 -0700 [thread overview]
Message-ID: <20180725223832.GA43733@beast> (raw)
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.
Signed-off-by: Kees Cook <keescook@chromium.org>
---
Documentation/admin-guide/kernel-parameters.txt | 5 +++--
mm/Kconfig.debug | 6 +++---
2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 533ff5c68970..f8a81b929089 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/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 --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index e5e606ee5f71..9a7b8b049d04 100644
--- a/mm/Kconfig.debug
+++ b/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"
--
2.17.1
--
Kees Cook
Pixel Security
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WARNING: multiple messages have this Message-ID (diff)
From: Kees Cook <keescook@chromium.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>,
Laura Abbott <labbott@redhat.com>,
linux-doc@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: [PATCH] mm: Clarify CONFIG_PAGE_POISONING and usage
Date: Wed, 25 Jul 2018 15:38:32 -0700 [thread overview]
Message-ID: <20180725223832.GA43733@beast> (raw)
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.
Signed-off-by: Kees Cook <keescook@chromium.org>
---
Documentation/admin-guide/kernel-parameters.txt | 5 +++--
mm/Kconfig.debug | 6 +++---
2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 533ff5c68970..f8a81b929089 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/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 --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index e5e606ee5f71..9a7b8b049d04 100644
--- a/mm/Kconfig.debug
+++ b/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"
--
2.17.1
--
Kees Cook
Pixel Security
next reply other threads:[~2018-07-25 22:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-25 22:38 Kees Cook [this message]
2018-07-25 22:38 ` [PATCH] mm: Clarify CONFIG_PAGE_POISONING and usage Kees Cook
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