arm64: Use pointer masking to limit uaccess speculation

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Commit 4d8efc2d5e upstream.

Similarly to x86, mitigate speculation past an access_ok() check by
masking the pointer against the address limit before use.

Even if we don't expect speculative writes per se, it is plausible that
a CPU may still speculate at least as far as fetching a cache line for
writing, hence we also harden put_user() and clear_user() for peace of
mind.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

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Robin Murphy 2018-02-05 15:34:19 +00:00 • committed by Greg Kroah-Hartman

parent 535357c9d3

commit 2e985d2647

1 changed files with 23 additions and 3 deletions

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arch/arm64/include/asm/uaccess.h

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