From 8eabf42ae5237e6b699aeac687b5b629e3537c8d Mon Sep 17 00:00:00 2001 From: Baoquan He Date: Tue, 27 Jun 2017 20:39:06 +0800 Subject: x86/boot/KASLR: Fix kexec crash due to 'virt_addr' calculation bug Kernel text KASLR is separated into physical address and virtual address randomization. And for virtual address randomization, we only randomiza to get an offset between 16M and KERNEL_IMAGE_SIZE. So the initial value of 'virt_addr' should be LOAD_PHYSICAL_ADDR, but not the original kernel loading address 'output'. The bug will cause kernel boot failure if kernel is loaded at a different position than the address, 16M, which is decided at compiled time. Kexec/kdump is such practical case. To fix it, just assign LOAD_PHYSICAL_ADDR to virt_addr as initial value. Tested-by: Dave Young Signed-off-by: Baoquan He Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 8391c73 ("x86/KASLR: Randomize virtual address separately") Link: http://lkml.kernel.org/r/1498567146-11990-3-git-send-email-bhe@redhat.com Signed-off-by: Ingo Molnar --- arch/x86/boot/compressed/misc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86/boot/compressed/misc.c') diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c index 6008fa9b74d9..00241c815524 100644 --- a/arch/x86/boot/compressed/misc.c +++ b/arch/x86/boot/compressed/misc.c @@ -338,7 +338,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, unsigned long output_len) { const unsigned long kernel_total_size = VO__end - VO__text; - unsigned long virt_addr = (unsigned long)output; + unsigned long virt_addr = LOAD_PHYSICAL_ADDR; /* Retain x86 boot parameters pointer passed from startup_32/64. */ boot_params = rmode; @@ -399,7 +399,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap, #ifndef CONFIG_RELOCATABLE if ((unsigned long)output != LOAD_PHYSICAL_ADDR) error("Destination address does not match LOAD_PHYSICAL_ADDR"); - if ((unsigned long)output != virt_addr) + if (virt_addr != LOAD_PHYSICAL_ADDR) error("Destination virtual address changed when not relocatable"); #endif -- cgit v1.2.1