brk: make sys_brk() honor COMPAT_BRK when computing lower bound
Fix a regression introduced by
commit 4cc6028d4040f95cdb590a87db478b42b8be0508
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: Jiri Kosina <jkosina@suse.cz>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/mmap.c b/mm/mmap.c
index 669499e..3354fdd 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -245,10 +245,16 @@
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;
/*