affs: bound hash_pos before table lookup in affs_readdir

affs_readdir() decodes ctx->pos into hash_pos and chain_pos and then
dereferences AFFS_HEAD(dir_bh)->table[hash_pos] before validating
that hash_pos is within the runtime table bound. Treat out-of-range
positions as end-of-directory before the first table lookup.

Signed-off-by: Hyungjung Joo <jhj140711@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/affs/dir.c b/fs/affs/dir.c
index 5c8d83387a394146f8df2e97af3b65723a076be1..075c18c4ccde64a69cbdcc6775555bb2aae94b15 100644 (file)
--- a/fs/affs/dir.c
+++ b/fs/affs/dir.c
@@ -119,6 +119,8 @@ affs_readdir(struct file *file, struct dir_context *ctx)
                pr_debug("readdir() left off=%d\n", ino);
                goto inside;
        }
+       if (hash_pos >= AFFS_SB(sb)->s_hashsize)
+               goto done;
 
        ino = be32_to_cpu(AFFS_HEAD(dir_bh)->table[hash_pos]);
        for (i = 0; ino && i < chain_pos; i++) {