From d7fd2941ae9a67423d1c7bee985f240e4686634f Mon Sep 17 00:00:00 2001 From: Alexander Gordeev Date: Wed, 21 Aug 2024 18:55:06 +0200 Subject: [PATCH] s390/boot: Avoid possible physmem_info segment corruption When physical memory for the kernel image is allocated it does not consider extra memory required for offsetting the image start to match it with the lower 20 bits of KASLR virtual base address. That might lead to kernel access beyond its memory range. Suggested-by: Vasily Gorbik Fixes: 693d41f7c938 ("s390/mm: Restore mapping of kernel image using large pages") Signed-off-by: Alexander Gordeev Acked-by: Vasily Gorbik Signed-off-by: Vasily Gorbik --- arch/s390/boot/startup.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c index cff34744b5a9b..d69f1dfd3b1e7 100644 --- a/arch/s390/boot/startup.c +++ b/arch/s390/boot/startup.c @@ -457,9 +457,9 @@ void startup_kernel(void) */ kaslr_large_page_offset = __kaslr_offset & ~_SEGMENT_MASK; if (kaslr_enabled()) { - unsigned long end = ident_map_size - kaslr_large_page_offset; + unsigned long size = kernel_size + kaslr_large_page_offset; - __kaslr_offset_phys = randomize_within_range(kernel_size, _SEGMENT_SIZE, 0, end); + __kaslr_offset_phys = randomize_within_range(size, _SEGMENT_SIZE, 0, ident_map_size); } if (!__kaslr_offset_phys) __kaslr_offset_phys = nokaslr_offset_phys;