From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 02CB015C83 for ; Mon, 5 Dec 2022 19:26:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5F30DC433C1; Mon, 5 Dec 2022 19:26:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1670268366; bh=ZPEcwlxSAlSYFdvr8SPLDAbU7FTX6XWVrnAybQy8PwE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dxqa1T5TnVIlAdWQjrJ5h1752yP7R1Pb60ADakibwPvoM1nnEqYoMxfEUO17JkTBW ko9QUVF5RvXrHrpnEXJFtbQmZkVkGoH1PjoEtFIZlsAirc4Q37Clzhx660nwkg+Mns yLLR4+F0woB485sg5OeVU8xONPRQ6YEBbcofWrxo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , Alexandre Ghiti , Palmer Dabbelt Subject: [PATCH 6.0 076/124] riscv: mm: Proper page permissions after initmem free Date: Mon, 5 Dec 2022 20:09:42 +0100 Message-Id: <20221205190810.579214841@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221205190808.422385173@linuxfoundation.org> References: <20221205190808.422385173@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Björn Töpel commit 6fdd5d2f8c2f54b7fad4ff4df2a19542aeaf6102 upstream. 64-bit RISC-V kernels have the kernel image mapped separately to alias the linear map. The linear map and the kernel image map are documented as "direct mapping" and "kernel" respectively in [1]. At image load time, the linear map corresponding to the kernel image is set to PAGE_READ permission, and the kernel image map is set to PAGE_READ|PAGE_EXEC. When the initmem is freed, the pages in the linear map should be restored to PAGE_READ|PAGE_WRITE, whereas the corresponding pages in the kernel image map should be restored to PAGE_READ, by removing the PAGE_EXEC permission. This is not the case. For 64-bit kernels, only the linear map is restored to its proper page permissions at initmem free, and not the kernel image map. In practise this results in that the kernel can potentially jump to dead __init code, and start executing invalid instructions, without getting an exception. Restore the freed initmem properly, by setting both the kernel image map to the correct permissions. [1] Documentation/riscv/vm-layout.rst Fixes: e5c35fa04019 ("riscv: Map the kernel with correct permissions the first time") Signed-off-by: Björn Töpel Reviewed-by: Alexandre Ghiti Tested-by: Alexandre Ghiti Link: https://lore.kernel.org/r/20221115090641.258476-1-bjorn@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt Signed-off-by: Greg Kroah-Hartman --- arch/riscv/kernel/setup.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) --- a/arch/riscv/kernel/setup.c +++ b/arch/riscv/kernel/setup.c @@ -322,10 +322,11 @@ subsys_initcall(topology_init); void free_initmem(void) { - if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) - set_kernel_memory(lm_alias(__init_begin), lm_alias(__init_end), - IS_ENABLED(CONFIG_64BIT) ? - set_memory_rw : set_memory_rw_nx); + if (IS_ENABLED(CONFIG_STRICT_KERNEL_RWX)) { + set_kernel_memory(lm_alias(__init_begin), lm_alias(__init_end), set_memory_rw_nx); + if (IS_ENABLED(CONFIG_64BIT)) + set_kernel_memory(__init_begin, __init_end, set_memory_nx); + } free_initmem_default(POISON_FREE_INITMEM); }