fs: avoid possible NULL dereference in fs_devread

It is unwise to first dereference a variable
and then to check if it was NULL.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Marek Behun <marek.behun@nic.cz>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

diff --git a/fs/fs_internal.c b/fs/fs_internal.c
index 58b441030c863dda0ce0ea202b949735e088d024..5cdd272c9de1ce59cfa252da4316aa8a052a5f0d 100644 (file)
--- a/fs/fs_internal.c
+++ b/fs/fs_internal.c
@@ -15,12 +15,13 @@ int fs_devread(struct blk_desc *blk, disk_partition_t *partition,
               lbaint_t sector, int byte_offset, int byte_len, char *buf)
 {
        unsigned block_len;
-       int log2blksz = blk->log2blksz;
+       int log2blksz;
        ALLOC_CACHE_ALIGN_BUFFER(char, sec_buf, (blk ? blk->blksz : 0));
        if (blk == NULL) {
                printf("** Invalid Block Device Descriptor (NULL)\n");
                return 0;
        }
+       log2blksz = blk->log2blksz;
 
        /* Check partition boundaries */
        if ((sector + ((byte_offset + byte_len - 1) >> log2blksz))