Subject: [PATCH] x86, boot, aslr: Use init_size instead of run_size commit e6023367d779 ("x86, kaslr: Prevent .bss from overlaping initrd") introduced one run_size for kaslr. We do not need to have home grown run_size. We should use real runtime size (include copy/decompress) aka init_size Please check arch/x86/boot/header.S about init_size for detail. Fixes: e6023367d779 ("x86, kaslr: Prevent .bss from overlaping initrd") Cc: "H. Peter Anvin" Cc: Josh Triplett Cc: Matt Fleming Cc: Kees Cook Cc: Andrew Morton Cc: Ard Biesheuvel Cc: Junjie Mao Signed-off-by: Yinghai Lu --- arch/x86/boot/compressed/Makefile | 4 --- arch/x86/boot/compressed/head_32.S | 5 +--- arch/x86/boot/compressed/head_64.S | 5 ---- arch/x86/boot/compressed/misc.c | 15 ++++++------- arch/x86/boot/compressed/mkpiggy.c | 9 +------ arch/x86/tools/calc_run_size.sh | 42 ------------------------------------- 6 files changed, 13 insertions(+), 67 deletions(-) Index: linux-2.6/arch/x86/boot/compressed/Makefile =================================================================== --- linux-2.6.orig/arch/x86/boot/compressed/Makefile +++ linux-2.6/arch/x86/boot/compressed/Makefile @@ -92,10 +92,8 @@ suffix-$(CONFIG_KERNEL_XZ) := xz suffix-$(CONFIG_KERNEL_LZO) := lzo suffix-$(CONFIG_KERNEL_LZ4) := lz4 -RUN_SIZE = $(shell $(OBJDUMP) -h vmlinux | \ - $(CONFIG_SHELL) $(srctree)/arch/x86/tools/calc_run_size.sh) quiet_cmd_mkpiggy = MKPIGGY $@ - cmd_mkpiggy = $(obj)/mkpiggy $< $(RUN_SIZE) > $@ || ( rm -f $@ ; false ) + cmd_mkpiggy = $(obj)/mkpiggy $< > $@ || ( rm -f $@ ; false ) targets += piggy.S $(obj)/piggy.S: $(obj)/vmlinux.bin.$(suffix-y) $(obj)/mkpiggy FORCE Index: linux-2.6/arch/x86/boot/compressed/head_32.S =================================================================== --- linux-2.6.orig/arch/x86/boot/compressed/head_32.S +++ linux-2.6/arch/x86/boot/compressed/head_32.S @@ -208,8 +208,7 @@ relocated: * Do the decompression, and jump to the new kernel.. */ /* push arguments for decompress_kernel: */ - pushl $z_run_size /* size of kernel with .bss and .brk */ - pushl $z_output_len /* decompressed length, end of relocs */ + pushl $z_output_len /* decompressed length */ leal z_extract_offset_negative(%ebx), %ebp pushl %ebp /* output address */ pushl $z_input_len /* input_len */ @@ -219,7 +218,7 @@ relocated: pushl %eax /* heap area */ pushl %esi /* real mode pointer */ call decompress_kernel /* returns kernel location in %eax */ - addl $28, %esp + addl $24, %esp /* * Jump to the decompressed kernel. Index: linux-2.6/arch/x86/boot/compressed/head_64.S =================================================================== --- linux-2.6.orig/arch/x86/boot/compressed/head_64.S +++ linux-2.6/arch/x86/boot/compressed/head_64.S @@ -403,16 +403,13 @@ relocated: * Do the decompression, and jump to the new kernel.. */ pushq %rsi /* Save the real mode argument */ - movq $z_run_size, %r9 /* size of kernel with .bss and .brk */ - pushq %r9 movq %rsi, %rdi /* real mode address */ leaq boot_heap(%rip), %rsi /* malloc area for uncompression */ leaq input_data(%rip), %rdx /* input_data */ movl $z_input_len, %ecx /* input_len */ movq %rbp, %r8 /* output target address */ - movq $z_output_len, %r9 /* decompressed length, end of relocs */ + movq $z_output_len, %r9 /* decompressed length */ call decompress_kernel /* returns kernel location in %rax */ - popq %r9 popq %rsi /* Index: linux-2.6/arch/x86/boot/compressed/misc.c =================================================================== --- linux-2.6.orig/arch/x86/boot/compressed/misc.c +++ linux-2.6/arch/x86/boot/compressed/misc.c @@ -370,10 +370,10 @@ asmlinkage __visible void *decompress_ke unsigned char *input_data, unsigned long input_len, unsigned char *output, - unsigned long output_len, - unsigned long run_size) + unsigned long output_len) { unsigned char *output_orig = output; + unsigned long init_size; real_mode = rmode; @@ -396,15 +396,14 @@ asmlinkage __visible void *decompress_ke free_mem_ptr = heap; /* Heap */ free_mem_end_ptr = heap + BOOT_HEAP_SIZE; + init_size = real_mode->hdr.init_size; + /* - * The memory hole needed for the kernel is the larger of either - * the entire decompressed kernel plus relocation table, or the - * entire decompressed kernel plus .bss and .brk sections. + * The memory hole needed for the kernel is init_size for running + * and init_size is bigger than output_len always. */ output = choose_kernel_location(real_mode, input_data, input_len, - output, - output_len > run_size ? output_len - : run_size); + output, init_size); /* Validate memory location choices. */ if ((unsigned long)output & (MIN_KERNEL_ALIGN - 1)) Index: linux-2.6/arch/x86/boot/compressed/mkpiggy.c =================================================================== --- linux-2.6.orig/arch/x86/boot/compressed/mkpiggy.c +++ linux-2.6/arch/x86/boot/compressed/mkpiggy.c @@ -36,13 +36,11 @@ int main(int argc, char *argv[]) uint32_t olen; long ilen; unsigned long offs; - unsigned long run_size; FILE *f = NULL; int retval = 1; - if (argc < 3) { - fprintf(stderr, "Usage: %s compressed_file run_size\n", - argv[0]); + if (argc < 2) { + fprintf(stderr, "Usage: %s compressed_file\n", argv[0]); goto bail; } @@ -76,7 +74,6 @@ int main(int argc, char *argv[]) offs += olen >> 12; /* Add 8 bytes for each 32K block */ offs += 64*1024 + 128; /* Add 64K + 128 bytes slack */ offs = (offs+4095) & ~4095; /* Round to a 4K boundary */ - run_size = atoi(argv[2]); printf(".section \".rodata..compressed\",\"a\",@progbits\n"); printf(".globl z_input_len\n"); @@ -88,8 +85,6 @@ int main(int argc, char *argv[]) /* z_extract_offset_negative allows simplification of head_32.S */ printf(".globl z_extract_offset_negative\n"); printf("z_extract_offset_negative = -0x%lx\n", offs); - printf(".globl z_run_size\n"); - printf("z_run_size = %lu\n", run_size); printf(".globl input_data, input_data_end\n"); printf("input_data:\n"); Index: linux-2.6/arch/x86/tools/calc_run_size.sh =================================================================== --- linux-2.6.orig/arch/x86/tools/calc_run_size.sh +++ /dev/null @@ -1,42 +0,0 @@ -#!/bin/sh -# -# Calculate the amount of space needed to run the kernel, including room for -# the .bss and .brk sections. -# -# Usage: -# objdump -h a.out | sh calc_run_size.sh - -NUM='\([0-9a-fA-F]*[ \t]*\)' -OUT=$(sed -n 's/^[ \t0-9]*.b[sr][sk][ \t]*'"$NUM$NUM$NUM$NUM"'.*/\1\4/p') -if [ -z "$OUT" ] ; then - echo "Never found .bss or .brk file offset" >&2 - exit 1 -fi - -OUT=$(echo ${OUT# }) -sizeA=$(printf "%d" 0x${OUT%% *}) -OUT=${OUT#* } -offsetA=$(printf "%d" 0x${OUT%% *}) -OUT=${OUT#* } -sizeB=$(printf "%d" 0x${OUT%% *}) -OUT=${OUT#* } -offsetB=$(printf "%d" 0x${OUT%% *}) - -run_size=$(( $offsetA + $sizeA + $sizeB )) - -# BFD linker shows the same file offset in ELF. -if [ "$offsetA" -ne "$offsetB" ] ; then - # Gold linker shows them as consecutive. - endB=$(( $offsetB + $sizeB )) - if [ "$endB" != "$run_size" ] ; then - printf "sizeA: 0x%x\n" $sizeA >&2 - printf "offsetA: 0x%x\n" $offsetA >&2 - printf "sizeB: 0x%x\n" $sizeB >&2 - printf "offsetB: 0x%x\n" $offsetB >&2 - echo ".bss and .brk are non-contiguous" >&2 - exit 1 - fi -fi - -printf "%d\n" $run_size -exit 0