brk: fix min_brk lower bound computation for COMPAT_BRK
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: NJiri Kosina <jkosina@suse.cz> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: NAndrew Morton <akpm@linux-foundation.org> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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