ext4: fix undefined behavior in ext4_fill_flex_info()

[karo-tx-linux.git] / fs / ext4 / super.c

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 36570b7af7c5cc59d5ff559547a6bcef21cd97fb..108c3af8617b534ef31ce81d65261f6e87bcbc35 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -2006,17 +2006,16 @@ static int ext4_fill_flex_info(struct super_block *sb)
        struct ext4_group_desc *gdp = NULL;
        ext4_group_t flex_group_count;
        ext4_group_t flex_group;
-       int groups_per_flex = 0;
+       unsigned int groups_per_flex = 0;
        size_t size;
        int i;
 
        sbi->s_log_groups_per_flex = sbi->s_es->s_log_groups_per_flex;
-       groups_per_flex = 1 << sbi->s_log_groups_per_flex;
-
-       if (groups_per_flex < 2) {
+       if (sbi->s_log_groups_per_flex < 1 || sbi->s_log_groups_per_flex > 31) {
                sbi->s_log_groups_per_flex = 0;
                return 1;
        }
+       groups_per_flex = 1 << sbi->s_log_groups_per_flex;
 
        /* We allocate both existing and potentially added groups */
        flex_group_count = ((sbi->s_groups_count + groups_per_flex - 1) +