diff options
Diffstat (limited to 'arch/x86/boot/compressed/kaslr.c')
| -rw-r--r-- | arch/x86/boot/compressed/kaslr.c | 32 |
1 files changed, 28 insertions, 4 deletions
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index e55ebcbfa290..016a4f48b19e 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -417,8 +417,8 @@ static void process_e820_entry(struct e820entry *entry, } } -static unsigned long find_random_addr(unsigned long minimum, - unsigned long size) +static unsigned long find_random_phys_addr(unsigned long minimum, + unsigned long image_size) { int i; unsigned long addr; @@ -428,12 +428,36 @@ static unsigned long find_random_addr(unsigned long minimum, /* Verify potential e820 positions, appending to slots list. */ for (i = 0; i < boot_params->e820_entries; i++) { - process_e820_entry(&boot_params->e820_map[i], minimum, size); + process_e820_entry(&boot_params->e820_map[i], minimum, + image_size); } return slots_fetch_random(); } +static unsigned long find_random_virt_addr(unsigned long minimum, + unsigned long image_size) +{ + unsigned long slots, random_addr; + + /* Make sure minimum is aligned. */ + minimum = ALIGN(minimum, CONFIG_PHYSICAL_ALIGN); + /* Align image_size for easy slot calculations. */ + image_size = ALIGN(image_size, CONFIG_PHYSICAL_ALIGN); + + /* + * There are how many CONFIG_PHYSICAL_ALIGN-sized slots + * that can hold image_size within the range of minimum to + * KERNEL_IMAGE_SIZE? + */ + slots = (KERNEL_IMAGE_SIZE - minimum - image_size) / + CONFIG_PHYSICAL_ALIGN + 1; + + random_addr = get_random_long() % slots; + + return random_addr * CONFIG_PHYSICAL_ALIGN + minimum; +} + /* * Since this function examines addresses much more numerically, * it takes the input and output pointers as 'unsigned long'. @@ -464,7 +488,7 @@ unsigned char *choose_random_location(unsigned long input, mem_avoid_init(input, input_size, output); /* Walk e820 and find a random address. */ - random_addr = find_random_addr(output, output_size); + random_addr = find_random_phys_addr(output, output_size); if (!random_addr) { warn("KASLR disabled: could not find suitable E820 region!"); goto out; |