mips: adjust brk randomization offset to fit generic version

This commit simply bumps up to 32MB and 1GB the random offset of brk,
compared to 8MB and 256MB, for 32bit and 64bit respectively.

Link: http://lkml.kernel.org/r/20190730055113.23635-12-alex@ghiti.fr
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Acked-by: Paul Burton <paul.burton@mips.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: James Hogan <jhogan@kernel.org>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/arch/mips/mm/mmap.c b/arch/mips/mm/mmap.c
index a7e84b2e71d75d402a0ce369b2c6057021fef94a..ff6ab87e9c563b61b0083ba4e470a23cf282d0c8 100644 (file)
--- a/arch/mips/mm/mmap.c
+++ b/arch/mips/mm/mmap.c
@@ -16,6 +16,7 @@
 #include <linux/random.h>
 #include <linux/sched/signal.h>
 #include <linux/sched/mm.h>
+#include <linux/sizes.h>
 
 unsigned long shm_align_mask = PAGE_SIZE - 1;  /* Sane caches */
 EXPORT_SYMBOL(shm_align_mask);
@@ -189,11 +190,11 @@ static inline unsigned long brk_rnd(void)
        unsigned long rnd = get_random_long();
 
        rnd = rnd << PAGE_SHIFT;
-       /* 8MB for 32bit, 256MB for 64bit */
+       /* 32MB for 32bit, 1GB for 64bit */
        if (TASK_IS_32BIT_ADDR)
-               rnd = rnd & 0x7ffffful;
+               rnd = rnd & (SZ_32M - 1);
        else
-               rnd = rnd & 0xffffffful;
+               rnd = rnd & (SZ_1G - 1);
 
        return rnd;
 }