arm64: Fix KASAN random tag seed initialization

[ Upstream commit f75c235565f90c4a17b125e47f1c68ef6b8c2bce ]

Currently, kasan_init_sw_tags() is called before setup_per_cpu_areas(),
so per_cpu(prng_state, cpu) accesses the same address regardless of the
value of "cpu", and the same seed value gets copied to the percpu area
for every CPU. Fix this by moving the call to smp_prepare_boot_cpu(),
which is the first architecture hook after setup_per_cpu_areas().

Fixes: 3c9e3aa11094 ("kasan: add tag related helper functions")
Fixes: 3f41b6093823 ("kasan: fix random seed generation for tag-based mode")
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Link: https://lore.kernel.org/r/20240814091005.969756-1-samuel.holland@sifive.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index a096e2451044d35bad506ecb67edcf3f2d30b87c..b22d28ec80284b1c4f593a4ffc51ed2b7012f7a3 100644 (file)
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -355,9 +355,6 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
        smp_init_cpus();
        smp_build_mpidr_hash();
 
-       /* Init percpu seeds for random tags after cpus are set up. */
-       kasan_init_sw_tags();
-
 #ifdef CONFIG_ARM64_SW_TTBR0_PAN
        /*
         * Make sure init_thread_info.ttbr0 always generates translation

diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 5de85dccc09cd526253795bec0e56630aa70b623..05688f6a275f10cbdaab45e5be68b05bd5f7d51b 100644 (file)
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -469,6 +469,8 @@ void __init smp_prepare_boot_cpu(void)
                init_gic_priority_masking();
 
        kasan_init_hw_tags();
+       /* Init percpu seeds for random tags after cpus are set up. */
+       kasan_init_sw_tags();
 }
 
 /*