• Vasily Kulikov's avatar
    include/linux/poison.h: fix LIST_POISON{1,2} offset · 8a5e5e02
    Vasily Kulikov authored
    Poison pointer values should be small enough to find a room in
    non-mmap'able/hardly-mmap'able space.  E.g.  on x86 "poison pointer space"
    is located starting from 0x0.  Given unprivileged users cannot mmap
    anything below mmap_min_addr, it should be safe to use poison pointers
    lower than mmap_min_addr.
    
    The current poison pointer values of LIST_POISON{1,2} might be too big for
    mmap_min_addr values equal or less than 1 MB (common case, e.g.  Ubuntu
    uses only 0x10000).  There is little point to use such a big value given
    the "poison pointer space" below 1 MB is not yet exhausted.  Changing it
    to a smaller value solves the problem for small mmap_min_addr setups.
    
    The values are suggested by Solar Designer:
    http://www.openwall.com/lists/oss-security/2015/05/02/6Signed-off-by: default avatarVasily Kulikov <segoon@openwall.com>
    Cc: Solar Designer <solar@openwall.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    8a5e5e02
poison.h 2.54 KB