ext2fs_read_inode: Check the validity of the inode number earlier

It looks like the right place to check for ino=0 in
ext2fs_read_inode_full() is before creating the inode cache, otherwise
since we set icache[i].ino = 0 in create_icache(), it will match the
loop below and thus we return a wrong value.

Signed-off-by: "Manish Katiyar" <mkatiyar@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/lib/ext2fs/inode.c b/lib/ext2fs/inode.c
index 8908423..ba15dda 100644 (file)
--- a/lib/ext2fs/inode.c
+++ b/lib/ext2fs/inode.c
@@ -536,6 +536,8 @@ errcode_t ext2fs_read_inode_full(ext2_filsys fs, ext2_ino_t ino,
                if (retval != EXT2_ET_CALLBACK_NOTHANDLED)
                        return retval;
        }
+       if ((ino == 0) || (ino > fs->super->s_inodes_count))
+               return EXT2_ET_BAD_INODE_NUM;
        /* Create inode cache if not present */
        if (!fs->icache) {
                retval = create_icache(fs);
@@ -544,7 +546,7 @@ errcode_t ext2fs_read_inode_full(ext2_filsys fs, ext2_ino_t ino,
        }
        /* Check to see if it's in the inode cache */
        if (bufsize == sizeof(struct ext2_inode)) {
-               /* only old good inode can be retrieve from the cache */
+               /* only old good inode can be retrieved from the cache */
                for (i=0; i < fs->icache->cache_size; i++) {
                        if (fs->icache->cache[i].ino == ino) {
                                *inode = fs->icache->cache[i].inode;
@@ -552,8 +554,6 @@ errcode_t ext2fs_read_inode_full(ext2_filsys fs, ext2_ino_t ino,
                        }
                }
        }
-       if ((ino == 0) || (ino > fs->super->s_inodes_count))
-               return EXT2_ET_BAD_INODE_NUM;
        if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
                inodes_per_block = fs->blocksize / EXT2_INODE_SIZE(fs->super);
                block_nr = fs->image_header->offset_inode / fs->blocksize;