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Commit a5b4592c authored by Jiri Kosina's avatar Jiri Kosina Committed by Linus Torvalds
Browse files

brk: make sys_brk() honor COMPAT_BRK when computing lower bound 



Fix a regression introduced by

commit 4cc6028d
Author: Jiri Kosina <jkosina@suse.cz>
Date:   Wed Feb 6 22:39:44 2008 +0100

    brk: check the lower bound properly

The check in sys_brk() on minimum value the brk might have must take
CONFIG_COMPAT_BRK setting into account.  When this option is turned on
(i.e.  we support ancient legacy binaries, e.g.  libc5-linked stuff), the
lower bound on brk value is mm->end_code, otherwise the brk start is
allowed to be arbitrarily shifted.

Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
Tested-by: default avatarGeert Uytterhoeven <geert@linux-m68k.org>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 33dda515

mm/mmap.c

+7 −1
Original line number Diff line number Diff line
@@ -245,10 +245,16 @@ asmlinkage unsigned long sys_brk(unsigned long brk) 
	unsigned long rlim, retval;

	unsigned long newbrk, oldbrk;

	struct mm_struct *mm = current->mm;

	unsigned long min_brk;



	down_write(&mm->mmap_sem);



	if (brk < mm->start_brk)

#ifdef CONFIG_COMPAT_BRK

	min_brk = mm->end_code;

#else

	min_brk = mm->start_brk;

#endif

	if (brk < min_brk)

		goto out;



	/*