No description
  • C 96.8%
  • Assembly 0.9%
  • Rust 0.7%
  • Shell 0.6%
  • Python 0.5%
  • Other 0.3%
Find a file
Yu Kuai 844b8cdc68 nbd: don't allow reconnect after disconnect
Following process can cause nbd_config UAF:

1) grab nbd_config temporarily;

2) nbd_genl_disconnect() flush all recv_work() and release the
initial reference:

  nbd_genl_disconnect
   nbd_disconnect_and_put
    nbd_disconnect
     flush_workqueue(nbd->recv_workq)
    if (test_and_clear_bit(NBD_RT_HAS_CONFIG_REF, ...))
     nbd_config_put
     -> due to step 1), reference is still not zero

3) nbd_genl_reconfigure() queue recv_work() again;

  nbd_genl_reconfigure
   config = nbd_get_config_unlocked(nbd)
   if (!config)
   -> succeed
   if (!test_bit(NBD_RT_BOUND, ...))
   -> succeed
   nbd_reconnect_socket
    queue_work(nbd->recv_workq, &args->work)

4) step 1) release the reference;

5) Finially, recv_work() will trigger UAF:

  recv_work
   nbd_config_put(nbd)
   -> nbd_config is freed
   atomic_dec(&config->recv_threads)
   -> UAF

Fix the problem by clearing NBD_RT_BOUND in nbd_genl_disconnect(), so
that nbd_genl_reconfigure() will fail.

Fixes: b7aa3d3938 ("nbd: add a reconfigure netlink command")
Reported-by: syzbot+6b0df248918b92c33e6a@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/675bfb65.050a0220.1a2d0d.0006.GAE@google.com/
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250103092859.3574648-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
History 2025-01-06 07:38:20 -07:00
arch
block
certs
crypto
Documentation
drivers
fs
include
init
io_uring
ipc
kernel
lib
LICENSES
mm
net
rust
samples
scripts
security
sound
tools
usr
virt
.clang-format
.clippy.toml
.cocciconfig
.editorconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
.rustfmt.toml
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS
Makefile
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.