Linux-XFS Archive on lore.kernel.org
 help / color / Atom feed
From: Eric Sandeen <sandeen@redhat.com>
To: linux-xfs@vger.kernel.org
Subject: [PATCH] xfs: fix boundary test in xfs_attr_shortform_verify
Date: Tue, 25 Aug 2020 15:25:29 -0500
Message-ID: <63722af5-2d8d-2455-17ee-988defd3126f@redhat.com> (raw)

The boundary test for the fixed-offset parts of xfs_attr_sf_entry
in xfs_attr_shortform_verify is off by one.  endp is the address
just past the end of the valid data; to check the last byte of
a structure at offset of size "size" we must subtract one.
(i.e. for an object at offset 10, size 4, last byte is 13 not 14).

This can be shown by:

# touch file
# setfattr -n root.a file

and subsequent verifications will fail when it's reread from disk.

This only matters for a last attribute which has a single-byte name
and no value, otherwise the combination of namelen & valuelen will
push endp out and this test won't fail.

Fixes: 1e1bbd8e7ee06 ("xfs: create structure verifier function for shortform xattrs")
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

diff --git a/fs/xfs/libxfs/xfs_attr_leaf.c b/fs/xfs/libxfs/xfs_attr_leaf.c
index 8623c815164a..a0cf22f0c904 100644
--- a/fs/xfs/libxfs/xfs_attr_leaf.c
+++ b/fs/xfs/libxfs/xfs_attr_leaf.c
@@ -1037,7 +1037,7 @@ xfs_attr_shortform_verify(
 		 * Check the fixed-offset parts of the structure are
 		 * within the data buffer.
 		 */
-		if (((char *)sfep + sizeof(*sfep)) >= endp)
+		if (((char *)sfep + sizeof(*sfep)-1) >= endp)
 			return __this_address;
 
 		/* Don't allow names with known bad length. */


             reply index

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-25 20:25 Eric Sandeen [this message]
2020-08-25 20:26 ` Darrick J. Wong
2020-08-25 22:41 ` Dave Chinner
2020-08-26 14:32   ` Eric Sandeen
2020-08-26 15:13     ` Darrick J. Wong
2020-08-26 15:39       ` Eric Sandeen
2020-08-26 15:43         ` Darrick J. Wong
2020-08-27  8:11       ` Christoph Hellwig
2020-08-26 16:19 ` [PATCH V2] " Eric Sandeen
2020-08-26 16:44   ` Darrick J. Wong
2020-08-26 17:07     ` Eric Sandeen
2020-09-01 12:59     ` Pavel Reichl
2020-08-27  8:12   ` Christoph Hellwig
2020-08-27 13:43     ` Eric Sandeen

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=63722af5-2d8d-2455-17ee-988defd3126f@redhat.com \
    --to=sandeen@redhat.com \
    --cc=linux-xfs@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-XFS Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-xfs/0 linux-xfs/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-xfs linux-xfs/ https://lore.kernel.org/linux-xfs \
		linux-xfs@vger.kernel.org
	public-inbox-index linux-xfs

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-xfs


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git