• Jiri Kosina's avatar
    brk: fix min_brk lower bound computation for COMPAT_BRK · 5520e894
    Jiri Kosina authored
    Even if CONFIG_COMPAT_BRK is set in the kernel configuration, it can still
    be overriden by randomize_va_space sysctl.
    
    If this is the case, the min_brk computation in sys_brk() implementation
    is wrong, as it solely takes into account COMPAT_BRK setting, assuming
    that brk start is not randomized.  But that might not be the case if
    randomize_va_space sysctl has been set to '2' at the time the binary has
    been loaded from disk.
    
    In such case, the check has to be done in a same way as in
    !CONFIG_COMPAT_BRK case.
    
    In addition to that, the check for the COMPAT_BRK case introduced back in
    a5b4592c ("brk: make sys_brk() honor COMPAT_BRK when computing lower
    bound") is slightly wrong -- the lower bound shouldn't be mm->end_code,
    but mm->end_data instead, as that's where the legacy applications expect
    brk section to start (i.e.  immediately after last global variable).
    
    [akpm@linux-foundation.org: fix comment]
    Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
    Cc: Geert Uytterhoeven <geert@linux-m68k.org>
    Cc: Ingo Molnar <mingo@elte.hu>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    5520e894
mmap.c 70 KB