From d9b5b658210f28ed9f70c757d553e679d76e2986 Mon Sep 17 00:00:00 2001 From: Marcin Nowakowski Date: Wed, 23 Nov 2016 14:43:45 +0100 Subject: [PATCH] MIPS: init: Ensure bootmem does not corrupt reserved memory Current init code initialises bootmem allocator with all of the low memory that it assumes is available, but does not check for reserved memory block, which can lead to corruption of data that may be stored there. Move bootmem's allocation map to a location that does not cross any reserved regions Signed-off-by: Marcin Nowakowski Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/14609/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/setup.c | 74 ++++++++++++++++++++++++++++++++++++++-- 1 file changed, 71 insertions(+), 3 deletions(-) diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c index 8ebad247ce82..64b38d400987 100644 --- a/arch/mips/kernel/setup.c +++ b/arch/mips/kernel/setup.c @@ -153,6 +153,35 @@ void __init detect_memory_region(phys_addr_t start, phys_addr_t sz_min, phys_add add_memory_region(start, size, BOOT_MEM_RAM); } +bool __init memory_region_available(phys_addr_t start, phys_addr_t size) +{ + int i; + bool in_ram = false, free = true; + + for (i = 0; i < boot_mem_map.nr_map; i++) { + phys_addr_t start_, end_; + + start_ = boot_mem_map.map[i].addr; + end_ = boot_mem_map.map[i].addr + boot_mem_map.map[i].size; + + switch (boot_mem_map.map[i].type) { + case BOOT_MEM_RAM: + if (start >= start_ && start + size <= end_) + in_ram = true; + break; + case BOOT_MEM_RESERVED: + if ((start >= start_ && start < end_) || + (start < start_ && start + size >= start_)) + free = false; + break; + default: + continue; + } + } + + return in_ram && free; +} + static void __init print_memory_map(void) { int i; @@ -332,11 +361,19 @@ static void __init bootmem_init(void) #else /* !CONFIG_SGI_IP27 */ +static unsigned long __init bootmap_bytes(unsigned long pages) +{ + unsigned long bytes = DIV_ROUND_UP(pages, 8); + + return ALIGN(bytes, sizeof(long)); +} + static void __init bootmem_init(void) { unsigned long reserved_end; unsigned long mapstart = ~0UL; unsigned long bootmap_size; + bool bootmap_valid = false; int i; /* @@ -430,11 +467,42 @@ static void __init bootmem_init(void) #endif /* - * Initialize the boot-time allocator with low memory only. + * check that mapstart doesn't overlap with any of + * memory regions that have been reserved through eg. DTB */ - bootmap_size = init_bootmem_node(NODE_DATA(0), mapstart, - min_low_pfn, max_low_pfn); + bootmap_size = bootmap_bytes(max_low_pfn - min_low_pfn); + + bootmap_valid = memory_region_available(PFN_PHYS(mapstart), + bootmap_size); + for (i = 0; i < boot_mem_map.nr_map && !bootmap_valid; i++) { + unsigned long mapstart_addr; + + switch (boot_mem_map.map[i].type) { + case BOOT_MEM_RESERVED: + mapstart_addr = PFN_ALIGN(boot_mem_map.map[i].addr + + boot_mem_map.map[i].size); + if (PHYS_PFN(mapstart_addr) < mapstart) + break; + + bootmap_valid = memory_region_available(mapstart_addr, + bootmap_size); + if (bootmap_valid) + mapstart = PHYS_PFN(mapstart_addr); + break; + default: + break; + } + } + if (!bootmap_valid) + panic("No memory area to place a bootmap bitmap"); + + /* + * Initialize the boot-time allocator with low memory only. + */ + if (bootmap_size != init_bootmem_node(NODE_DATA(0), mapstart, + min_low_pfn, max_low_pfn)) + panic("Unexpected memory size required for bootmap"); for (i = 0; i < boot_mem_map.nr_map; i++) { unsigned long start, end; -- GitLab