From 1598ecda7b239e9232dda032bfddeed9d89fab6c Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Tue, 15 Jan 2019 20:47:07 +0100 Subject: [PATCH] arm64: kaslr: ensure randomized quantities are clean to the PoC kaslr_early_init() is called with the kernel mapped at its link time offset, and if it returns with a non-zero offset, the kernel is unmapped and remapped again at the randomized offset. During its execution, kaslr_early_init() also randomizes the base of the module region and of the linear mapping of DRAM, and sets two variables accordingly. However, since these variables are assigned with the caches on, they may get lost during the cache maintenance that occurs when unmapping and remapping the kernel, so ensure that these values are cleaned to the PoC. Acked-by: Catalin Marinas Fixes: f80fb3a3d508 ("arm64: add support for kernel ASLR") Cc: # v4.6+ Signed-off-by: Ard Biesheuvel Signed-off-by: Will Deacon --- arch/arm64/kernel/kaslr.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/kaslr.c b/arch/arm64/kernel/kaslr.c index f0e6ab8abe9c..ba6b41790fcd 100644 --- a/arch/arm64/kernel/kaslr.c +++ b/arch/arm64/kernel/kaslr.c @@ -14,6 +14,7 @@ #include #include +#include #include #include #include @@ -43,7 +44,7 @@ static __init u64 get_kaslr_seed(void *fdt) return ret; } -static __init const u8 *get_cmdline(void *fdt) +static __init const u8 *kaslr_get_cmdline(void *fdt) { static __initconst const u8 default_cmdline[] = CONFIG_CMDLINE; @@ -109,7 +110,7 @@ u64 __init kaslr_early_init(u64 dt_phys) * Check if 'nokaslr' appears on the command line, and * return 0 if that is the case. */ - cmdline = get_cmdline(fdt); + cmdline = kaslr_get_cmdline(fdt); str = strstr(cmdline, "nokaslr"); if (str == cmdline || (str > cmdline && *(str - 1) == ' ')) return 0; @@ -169,5 +170,8 @@ u64 __init kaslr_early_init(u64 dt_phys) module_alloc_base += (module_range * (seed & ((1 << 21) - 1))) >> 21; module_alloc_base &= PAGE_MASK; + __flush_dcache_area(&module_alloc_base, sizeof(module_alloc_base)); + __flush_dcache_area(&memstart_offset_seed, sizeof(memstart_offset_seed)); + return offset; } -- 2.45.2