ext4: address UBSAN warning in mb_find_order_for_block()

[mirror_ubuntu-bionic-kernel.git] / fs / ext4 / mballoc.c

diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index efa111a7606dd13d62215694d5a2278a1cfd50c0..49e444b51a0c8044108036811d1ea43716516f87 100644 (file)
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -1266,6 +1266,7 @@ static void ext4_mb_unload_buddy(struct ext4_buddy *e4b)
 static int mb_find_order_for_block(struct ext4_buddy *e4b, int block)
 {
        int order = 1;
+       int bb_incr = 1 << (e4b->bd_blkbits - 1);
        void *bb;
 
        BUG_ON(e4b->bd_bitmap == e4b->bd_buddy);
@@ -1278,7 +1279,8 @@ static int mb_find_order_for_block(struct ext4_buddy *e4b, int block)
                        /* this block is part of buddy of order 'order' */
                        return order;
                }
-               bb += 1 << (e4b->bd_blkbits - order);
+               bb += bb_incr;
+               bb_incr >>= 1;
                order++;
        }
        return 0;