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| author | Catalin Marinas <catalin.marinas@arm.com> | 2022-06-10 17:21:41 +0200 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2022-07-07 11:48:37 +0200 |
| commit | 20794545c14692094a882d2221c251c4573e6adf (patch) | |
| tree | 1c06ac7b159e2ccb16315df9af074082d5a8640a /kernel/rseq.c | |
| parent | mm: kasan: Skip page unpoisoning only if __GFP_SKIP_KASAN_UNPOISON (diff) | |
| download | linux-20794545c14692094a882d2221c251c4573e6adf.tar.xz linux-20794545c14692094a882d2221c251c4573e6adf.zip | |
arm64: kasan: Revert "arm64: mte: reset the page tag in page->flags"
This reverts commit e5b8d9218951e59df986f627ec93569a0d22149b.
Pages mapped in user-space with PROT_MTE have the allocation tags either
zeroed or copied/restored to some user values. In order for the kernel
to access such pages via page_address(), resetting the tag in
page->flags was necessary. This tag resetting was deferred to
set_pte_at() -> mte_sync_page_tags() but it can race with another CPU
reading the flags (via page_to_virt()):
P0 (mte_sync_page_tags): P1 (memcpy from virt_to_page):
Rflags!=0xff
Wflags=0xff
DMB (doesn't help)
Wtags=0
Rtags=0 // fault
Since now the post_alloc_hook() function resets the page->flags tag when
unpoisoning is skipped for user pages (including the __GFP_ZEROTAGS
case), revert the arm64 commit calling page_kasan_tag_reset().
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Peter Collingbourne <pcc@google.com>
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Acked-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20220610152141.2148929-5-catalin.marinas@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'kernel/rseq.c')
0 files changed, 0 insertions, 0 deletions