From ab4ece4e9b1302bfb8453aa4fe4b2a3388bf476f Mon Sep 17 00:00:00 2001
From: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date: Sun, 27 Jan 2019 09:29:42 +0100
Subject: [PATCH] arm64: kaslr: ensure randomized quantities are clean also
when kaslr is off
commit 8ea235932314311f15ea6cf65c1393ed7e31af70 upstream.
Commit 1598ecda7b23 ("arm64: kaslr: ensure randomized quantities are
clean to the PoC") added cache maintenance to ensure that global
variables set by the kaslr init routine are not wiped clean due to
cache invalidation occurring during the second round of page table
creation.
However, if kaslr_early_init() exits early with no randomization
being applied (either due to the lack of a seed, or because the user
has disabled kaslr explicitly), no cache maintenance is performed,
leading to the same issue we attempted to fix earlier, as far as the
module_alloc_base variable is concerned.
Note that module_alloc_base cannot be initialized statically, because
that would cause it to be subject to a R_AARCH64_RELATIVE relocation,
causing it to be overwritten by the second round of KASLR relocation
processing.
Fixes: f80fb3a3d508 ("arm64: add support for kernel ASLR")
Cc: <stable@vger.kernel.org> # v4.6+
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm64/kernel/kaslr.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c
index 2bda224e8e71..ae7278286094 100644
--- a/arch/arm64/kernel/kaslr.c
+++ b/arch/arm64/kernel/kaslr.c
@@ -88,6 +88,7 @@ u64 __init kaslr_early_init(u64 dt_phys)
* we end up running with module randomization disabled.
*/
module_alloc_base = (u64)_etext - MODULES_VSIZE;
+ __flush_dcache_area(&module_alloc_base, sizeof(module_alloc_base));
/*
* Try to map the FDT early. If this fails, we simply bail,