arm64: uaccess: Prevent speculative use of the current addr_limit

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Commit c2f0ad4fc0 upstream.

A mispredicted conditional call to set_fs could result in the wrong
addr_limit being forwarded under speculation to a subsequent access_ok
check, potentially forming part of a spectre-v1 attack using uaccess
routines.

This patch prevents this forwarding from taking place, but putting heavy
barriers in set_fs after writing the addr_limit.

Reviewed-by: Mark Rutland <mark.rutland@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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Will Deacon 2018-02-05 15:34:21 +00:00 • committed by Greg Kroah-Hartman

parent 7a51d7d2f7

commit 1ccaee9dea

1 changed files with 7 additions and 0 deletions

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arch/arm64/include/asm/uaccess.h

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