Patch "fuse: listxattr: verify xattr list" has been added to the 4.4-stable tree

Patch "fuse: listxattr: verify xattr list" has been added to the 4.4-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    fuse: listxattr: verify xattr list

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     fuse-listxattr-verify-xattr-list.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From cb3ae6d25a5471be62bfe6ac1fccc0e91edeaba0 Mon Sep 17 00:00:00 2001
From: Miklos Szeredi <mszeredi@redhat.com>
Date: Sat, 1 Oct 2016 07:32:32 +0200
Subject: fuse: listxattr: verify xattr list

From: Miklos Szeredi <mszeredi@redhat.com>

commit cb3ae6d25a5471be62bfe6ac1fccc0e91edeaba0 upstream.

Make sure userspace filesystem is returning a well formed list of xattr
names (zero or more nonzero length, null terminated strings).

[Michael Theall: only verify in the nonzero size case]

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/fuse/dir.c |   19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -1797,6 +1797,23 @@ static ssize_t fuse_getxattr(struct dent
 	return ret;
 }
 
+static int fuse_verify_xattr_list(char *list, size_t size)
+{
+	size_t origsize = size;
+
+	while (size) {
+		size_t thislen = strnlen(list, size);
+
+		if (!thislen || thislen == size)
+			return -EIO;
+
+		size -= thislen + 1;
+		list += thislen + 1;
+	}
+
+	return origsize;
+}
+
 static ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size)
 {
 	struct inode *inode = d_inode(entry);
@@ -1832,6 +1849,8 @@ static ssize_t fuse_listxattr(struct den
 	ret = fuse_simple_request(fc, &args);
 	if (!ret && !size)
 		ret = outarg.size;
+	if (ret > 0 && size)
+		ret = fuse_verify_xattr_list(list, ret);
 	if (ret == -ENOSYS) {
 		fc->no_listxattr = 1;
 		ret = -EOPNOTSUPP;


Patches currently in stable-queue which might be from mszeredi@redhat.com are

queue-4.4/fuse-listxattr-verify-xattr-list.patch
queue-4.4/fuse-invalidate-dir-dentry-after-chmod.patch
queue-4.4/fuse-fix-killing-sid-in-setattr.patch