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authorVlastimil Babka <vbabka@suse.cz>2020-12-14 19:13:41 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2020-12-15 12:13:46 -0800
commit8f424750baaafcef229791882e879da01c9473b5 (patch)
tree01453fbaf9e238df6de2d898a4490e01ab2d986c /mm/page_poison.c
parent03b6c9a3e8805606c0bb4ad41855fac3bf85c3b9 (diff)
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mm, page_poison: remove CONFIG_PAGE_POISONING_NO_SANITY
CONFIG_PAGE_POISONING_NO_SANITY skips the check on page alloc whether the poison pattern was corrupted, suggesting a use-after-free. The motivation to introduce it in commit 8823b1dbc05f ("mm/page_poison.c: enable PAGE_POISONING as a separate option") was to simply sanitize freed pages, optimally together with CONFIG_PAGE_POISONING_ZERO. These days we have an init_on_free=1 boot option, which makes this use case of page poisoning redundant. For sanitizing, writing zeroes is sufficient, there is pretty much no benefit from writing the 0xAA poison pattern to freed pages, without checking it back on alloc. Thus, remove this option and suggest init_on_free instead in the main config's help. Link: https://lkml.kernel.org/r/20201113104033.22907-5-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: David Hildenbrand <david@redhat.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Alexander Potapenko <glider@google.com> Cc: Kees Cook <keescook@chromium.org> Cc: Laura Abbott <labbott@kernel.org> Cc: Mateusz Nosek <mateusznosek0@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_poison.c')
-rw-r--r--mm/page_poison.c3
1 files changed, 0 insertions, 3 deletions
diff --git a/mm/page_poison.c b/mm/page_poison.c
index 4d75fc9ccc7a..06ec518b2089 100644
--- a/mm/page_poison.c
+++ b/mm/page_poison.c
@@ -51,9 +51,6 @@ static void check_poison_mem(unsigned char *mem, size_t bytes)
unsigned char *start;
unsigned char *end;
- if (IS_ENABLED(CONFIG_PAGE_POISONING_NO_SANITY))
- return;
-
start = memchr_inv(mem, PAGE_POISON, bytes);
if (!start)
return;