• Suresh Siddha's avatar
    [PATCH] x86_64: TASK_SIZE fixes for compatibility mode processes · 84929801
    Suresh Siddha authored
    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: default avatarZou Nan hai <nanhai.zou@intel.com>
    Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
    Cc: Andi Kleen <ak@muc.de>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    84929801
ia32_binfmt.c 11.9 KB