exfat: Fix potential use after free in exfat_load_upcase_table()

This code calls brelse(bh) and then dereferences "bh" on the next line
resulting in a possible use after free.  The brelse() should just be
moved down a line.

Fixes: b676fdbcf4c8 ("exfat: standardize checksum calculation")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>

diff --git a/fs/exfat/nls.c b/fs/exfat/nls.c
index c1ec05695497445934ac8f2d537ccd131e5d7f5c..57b5a7a4d1f7a18b1854348bd6841ea7bc9c466a 100644 (file)
--- a/fs/exfat/nls.c
+++ b/fs/exfat/nls.c
@@ -692,8 +692,8 @@ static int exfat_load_upcase_table(struct super_block *sb,
                                index++;
                        }
                }
-               brelse(bh);
                chksum = exfat_calc_chksum32(bh->b_data, i, chksum, CS_DEFAULT);
+               brelse(bh);
        }
 
        if (index >= 0xFFFF && utbl_checksum == chksum)