From: Vasily Gorbik Date: Wed, 15 Mar 2023 12:54:14 +0000 (+0100) Subject: s390/kaslr: randomize amode31 base address X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=b3e0423c4e76b19f04799e01b6443949f5fecbbc;p=linux.git s390/kaslr: randomize amode31 base address When the KASLR is enabled, randomize the base address of the amode31 image within the first 2 GB, similar to the approach taken for the vmlinux image. This makes it harder to predict the location of amode31 data and code. Reviewed-by: Alexander Gordeev Signed-off-by: Vasily Gorbik --- diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c index 638a6cf8a075b..64bd7ac3e35d1 100644 --- a/arch/s390/boot/startup.c +++ b/arch/s390/boot/startup.c @@ -278,7 +278,7 @@ void startup_kernel(void) { unsigned long max_physmem_end; unsigned long vmlinux_lma = 0; - unsigned long amode31_lma; + unsigned long amode31_lma = 0; unsigned long asce_limit; unsigned long safe_addr; void *img; @@ -338,7 +338,9 @@ void startup_kernel(void) /* vmlinux decompression is done, shrink reserved low memory */ physmem_reserve(RR_DECOMPRESSOR, 0, (unsigned long)_decompressor_end); - amode31_lma = vmlinux.default_lma - vmlinux.amode31_size; + if (kaslr_enabled()) + amode31_lma = randomize_within_range(vmlinux.amode31_size, PAGE_SIZE, 0, SZ_2G); + amode31_lma = amode31_lma ?: vmlinux.default_lma - vmlinux.amode31_size; physmem_reserve(RR_AMODE31, amode31_lma, vmlinux.amode31_size); /*