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f6bbf0010b
When the 'v->config_ctx' eventfd_ctx reference is released we didn't
set it to NULL. So if the same character device (e.g. /dev/vhost-vdpa-0)
is re-opened, the 'v->config_ctx' is invalid and calling again
vhost_vdpa_config_put() causes use-after-free issues like the
following refcount_t underflow:
refcount_t: underflow; use-after-free.
WARNING: CPU: 2 PID: 872 at lib/refcount.c:28 refcount_warn_saturate+0xae/0xf0
RIP: 0010:refcount_warn_saturate+0xae/0xf0
Call Trace:
eventfd_ctx_put+0x5b/0x70
vhost_vdpa_release+0xcd/0x150 [vhost_vdpa]
__fput+0x8e/0x240
____fput+0xe/0x10
task_work_run+0x66/0xa0
exit_to_user_mode_prepare+0x118/0x120
syscall_exit_to_user_mode+0x21/0x50
? __x64_sys_close+0x12/0x40
do_syscall_64+0x45/0x50
entry_SYSCALL_64_after_hwframe+0x44/0xae
Fixes: 776f395004 ("vhost_vdpa: Support config interrupt in vdpa")
Cc: lingshan.zhu@intel.com
Cc: stable@vger.kernel.org
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Link: https://lore.kernel.org/r/20210311135257.109460-2-sgarzare@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Zhu Lingshan <lingshan.zhu@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
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 Restructured Text 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.