[PATCH 1/1] affs: bound hash_pos before table lookup in affs_readdir

[David Sterba]

From: Hyungjung Joo <jhj140711@xxxxxxxxx>

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@xxxxxxxxx>
Reviewed-by: David Sterba <dsterba@xxxxxxxx>
Signed-off-by: David Sterba <dsterba@xxxxxxxx>
---
 fs/affs/dir.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fs/affs/dir.c b/fs/affs/dir.c
index 5c8d83387a39..075c18c4ccde 100644
--- 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++) {
-- 
2.51.0