From 84929801e14d968caeb84795bfbb88f04283fbd9 Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Tue, 21 Jun 2005 17:14:32 -0700 Subject: [PATCH] x86_64: TASK_SIZE fixes for compatibility mode processes Appended patch will setup compatibility mode TASK_SIZE properly. This will fix atleast three known bugs that can be encountered while running compatibility mode apps. a) A malicious 32bit app can have an elf section at 0xffffe000. During exec of this app, we will have a memory leak as insert_vm_struct() is not checking for return value in syscall32_setup_pages() and thus not freeing the vma allocated for the vsyscall page. And instead of exec failing (as it has addresses > TASK_SIZE), we were allowing it to succeed previously. b) With a 32bit app, hugetlb_get_unmapped_area/arch_get_unmapped_area may return addresses beyond 32bits, ultimately causing corruption because of wrap-around and resulting in SEGFAULT, instead of returning ENOMEM. c) 32bit app doing this below mmap will now fail. mmap((void *)(0xFFFFE000UL), 0x10000UL, PROT_READ|PROT_WRITE, MAP_FIXED|MAP_PRIVATE|MAP_ANON, 0, 0); Signed-off-by: Zou Nan hai Signed-off-by: Suresh Siddha Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/asm-x86_64/processor.h | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'include/asm-x86_64/processor.h') diff --git a/include/asm-x86_64/processor.h b/include/asm-x86_64/processor.h index d641b19f6da5..8b55f139968f 100644 --- a/include/asm-x86_64/processor.h +++ b/include/asm-x86_64/processor.h @@ -160,16 +160,17 @@ static inline void clear_in_cr4 (unsigned long mask) /* * User space process size. 47bits minus one guard page. */ -#define TASK_SIZE (0x800000000000UL - 4096) +#define TASK_SIZE64 (0x800000000000UL - 4096) /* This decides where the kernel will search for a free chunk of vm * space during mmap's. */ #define IA32_PAGE_OFFSET ((current->personality & ADDR_LIMIT_3GB) ? 0xc0000000 : 0xFFFFe000) -#define TASK_UNMAPPED_32 PAGE_ALIGN(IA32_PAGE_OFFSET/3) -#define TASK_UNMAPPED_64 PAGE_ALIGN(TASK_SIZE/3) -#define TASK_UNMAPPED_BASE \ - (test_thread_flag(TIF_IA32) ? TASK_UNMAPPED_32 : TASK_UNMAPPED_64) + +#define TASK_SIZE (test_thread_flag(TIF_IA32) ? IA32_PAGE_OFFSET : TASK_SIZE64) +#define TASK_SIZE_OF(child) ((test_tsk_thread_flag(child, TIF_IA32)) ? IA32_PAGE_OFFSET : TASK_SIZE64) + +#define TASK_UNMAPPED_BASE PAGE_ALIGN(TASK_SIZE/3) /* * Size of io_bitmap. -- cgit v1.2.3