Re: [PATCH 1/1] hfsplus: fix longname handling

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On 02/25/2014 09:37 AM, Vyacheslav Dubeyko wrote:
Hi Sougata,

On Mon, 2014-02-24 at 21:28 +0200, Sougata Santra wrote:
-ENAMETOOLONG returned from hfsplus_asc2uni was not propaged to iops. This
allowed hfsplus to create files/directories with HFSPLUS_MAX_STRLEN and
incorrect keys, leaving the FS in an inconsistent state. This patch fixes
this issue.


Good fix. Thank you.

Thank you for taking time to look into it.

I have some small remarks. Please, see below.

Signed-off-by: Sougata Santra <sougata@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
  fs/hfsplus/catalog.c    | 89 ++++++++++++++++++++++++++++++++++++-------------
  fs/hfsplus/dir.c        | 11 ++++--
  fs/hfsplus/hfsplus_fs.h |  4 ++-
  fs/hfsplus/super.c      |  4 ++-
  4 files changed, 79 insertions(+), 29 deletions(-)

diff --git a/fs/hfsplus/catalog.c b/fs/hfsplus/catalog.c
index 968ce41..389c474 100644
--- a/fs/hfsplus/catalog.c
+++ b/fs/hfsplus/catalog.c
@@ -38,21 +38,30 @@ int hfsplus_cat_bin_cmp_key(const hfsplus_btree_key *k1,
  	return hfsplus_strcmp(&k1->cat.name, &k2->cat.name);
  }

-void hfsplus_cat_build_key(struct super_block *sb, hfsplus_btree_key *key,
-			   u32 parent, struct qstr *str)
+/* Generates key for catalog file/folders record. */
+int hfsplus_cat_build_key(struct super_block *sb,
+		hfsplus_btree_key *key, u32 parent, struct qstr *str)
  {
-	int len;
+	int len, err;

  	key->cat.parent = cpu_to_be32(parent);
-	if (str) {
-		hfsplus_asc2uni(sb, &key->cat.name, HFSPLUS_MAX_STRLEN,
-					str->name, str->len);
-		len = be16_to_cpu(key->cat.name.length);
-	} else {
-		key->cat.name.length = 0;
-		len = 0;
-	}
+	err = hfsplus_asc2uni(sb, &key->cat.name, HFSPLUS_MAX_STRLEN,
+			str->name, str->len);
+	if (unlikely(err < 0))
+		return err;
+
+	len = be16_to_cpu(key->cat.name.length);
  	key->key_len = cpu_to_be16(6 + 2 * len);

I think that maybe it is time to change hardcoded 6 on sensible named
constant. What do you think?

I agree, although I think this should he done in a separate patch. Also there are other instances of hard-coding. We can clean them with a patch. ?


+	return 0;
+}
+
+/* Generates key for catalog thread record. */
+void hfsplus_cat_build_key_with_cnid(struct super_block *sb,
+			hfsplus_btree_key *key, u32 parent)
+{
+	key->cat.parent = cpu_to_be32(parent);
+	key->cat.name.length = 0;
+	key->key_len = cpu_to_be16(6);

Ditto.

  }

  static void hfsplus_cat_build_key_uni(hfsplus_btree_key *key, u32 parent,

We have such code for hfsplus_cat_build_key_uni():

  58 static void hfsplus_cat_build_key_uni(hfsplus_btree_key *key, u32 parent,
  59                                       struct hfsplus_unistr *name)
  60 {
  61         int ustrlen;
  62
  63         ustrlen = be16_to_cpu(name->length);

I suppose that it makes sense to check name->length here and return
error. We can check possible volume corruption here.

I looked into it while writing the patch. I think this was already handled before. Please see. catalog.c#hfsplus_find_cat the only place it is called.

{code}
        if (be16_to_cpu(tmp.thread.nodeName.length) > 255) {
                pr_err("catalog name length corrupted\n");
                return -EIO;
        }
{code}


  64         key->cat.parent = cpu_to_be32(parent);
  65         key->cat.name.length = cpu_to_be16(ustrlen);
  66         ustrlen *= 2;
  67         memcpy(key->cat.name.unicode, name->unicode, ustrlen);
  68         key->key_len = cpu_to_be16(6 + ustrlen);
  69 }

What do you think about such suggestion?

diff --git a/fs/hfsplus/hfsplus_fs.h b/fs/hfsplus/hfsplus_fs.h
index 08846425b..66671c4 100644
--- a/fs/hfsplus/hfsplus_fs.h
+++ b/fs/hfsplus/hfsplus_fs.h
@@ -443,8 +443,10 @@ int hfsplus_cat_case_cmp_key(const hfsplus_btree_key *,
  		const hfsplus_btree_key *);
  int hfsplus_cat_bin_cmp_key(const hfsplus_btree_key *,
  		const hfsplus_btree_key *);
-void hfsplus_cat_build_key(struct super_block *sb,
+int hfsplus_cat_build_key(struct super_block *sb,
  		hfsplus_btree_key *, u32, struct qstr *);
+void hfsplus_cat_build_key_with_cnid(struct super_block *sb,

The whole style of the fix is good. But such mess looks not very good.
But it is not critical, of course. :)

Thank you for taking time to read it.

Thanks,
Vyacheslav Dubeyko.


Best regards,
    Sougata
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