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f1940d4e9c
The following crash happens when a never-used device is unbound from
uio_hv_generic driver:
kernel BUG at mm/slub.c:321!
invalid opcode: 0000 [#1] SMP PTI
CPU: 0 PID: 4001 Comm: bash Kdump: loaded Tainted: G X --------- --- 5.14.0-0.rc2.23.el9.x86_64 #1
Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS 090008 12/07/2018
RIP: 0010:__slab_free+0x1d5/0x3d0
...
Call Trace:
? pick_next_task_fair+0x18e/0x3b0
? __cond_resched+0x16/0x40
? vunmap_pmd_range.isra.0+0x154/0x1c0
? __vunmap+0x22d/0x290
? hv_ringbuffer_cleanup+0x36/0x40 [hv_vmbus]
kfree+0x331/0x380
? hv_uio_remove+0x43/0x60 [uio_hv_generic]
hv_ringbuffer_cleanup+0x36/0x40 [hv_vmbus]
vmbus_free_ring+0x21/0x60 [hv_vmbus]
hv_uio_remove+0x4f/0x60 [uio_hv_generic]
vmbus_remove+0x23/0x30 [hv_vmbus]
__device_release_driver+0x17a/0x230
device_driver_detach+0x3c/0xa0
unbind_store+0x113/0x130
...
The problem appears to be that we free 'ring_info->pkt_buffer' twice:
first, when the device is unbound from in-kernel driver (netvsc in this
case) and second from hv_uio_remove(). Normally, ring buffer is supposed
to be re-initialized from hv_uio_open() but this happens when UIO device
is being opened and this is not guaranteed to happen.
Generally, it is OK to call hv_ringbuffer_cleanup() twice for the same
channel (which is being handed over between in-kernel drivers and UIO) even
if we didn't call hv_ringbuffer_init() in between. We, however, need to
avoid kfree() call for an already freed pointer.
Fixes: adae1e931a ("Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Andrea Parri <parri.andrea@gmail.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20210831143916.144983-1-vkuznets@redhat.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
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.