linux-kernel - Re: [PATCH v2] arm64: extable: fix load_unaligned

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Message-Id: <164322343553.819367.16239308759447224919.b4-ty@arm.com>
Date:   Wed, 26 Jan 2022 18:57:21 +0000
From:   Catalin Marinas <catalin.marinas@....com>
To:     Robin Murphy <robin.murphy@....com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Will Deacon <will@...nel.org>,
        Jisheng Zhang <jszhang@...nel.org>,
        Evgenii Stepanov <eugenis@...gle.com>
Cc:     stable@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2] arm64: extable: fix load_unaligned_zeropad() reg indices

On Tue, 25 Jan 2022 10:22:17 -0800, Evgenii Stepanov wrote:
> In ex_handler_load_unaligned_zeropad() we erroneously extract the data and
> addr register indices from ex->type rather than ex->data. As ex->type will
> contain EX_TYPE_LOAD_UNALIGNED_ZEROPAD (i.e. 4):
>  * We'll always treat X0 as the address register, since EX_DATA_REG_ADDR is
>    extracted from bits [9:5]. Thus, we may attempt to dereference an
>    arbitrary address as X0 may hold an arbitrary value.
>  * We'll always treat X4 as the data register, since EX_DATA_REG_DATA is
>    extracted from bits [4:0]. Thus we will corrupt X4 and cause arbitrary
>    behaviour within load_unaligned_zeropad() and its caller.
> 
> [...]

Applied to arm64 (for-next/fixes), thanks!

[1/1] arm64: extable: fix load_unaligned_zeropad() reg indices
      https://git.kernel.org/arm64/c/afa1bf69aac3

-- 
Catalin