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authorVitaly Kuznetsov <vkuznets@redhat.com>2021-08-31 17:39:16 +0300
committerWei Liu <wei.liu@kernel.org>2021-09-03 14:00:06 +0300
commitf1940d4e9cbe6208e7e77e433c587af108152a17 (patch)
tree843b5dbae2a0f3e567f2c3e8858a5695d8b3c0ac /drivers/hv/ring_buffer.c
parent7d2a07b769330c34b4deabeed939325c77a7ec2f (diff)
downloadlinux-f1940d4e9cbe6208e7e77e433c587af108152a17.tar.xz
Drivers: hv: vmbus: Fix kernel crash upon unbinding a device from uio_hv_generic driver
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: adae1e931acd ("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>
Diffstat (limited to 'drivers/hv/ring_buffer.c')
-rw-r--r--drivers/hv/ring_buffer.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
index 2aee356840a2..314015d9e912 100644
--- a/drivers/hv/ring_buffer.c
+++ b/drivers/hv/ring_buffer.c
@@ -245,6 +245,7 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
mutex_unlock(&ring_info->ring_buffer_mutex);
kfree(ring_info->pkt_buffer);
+ ring_info->pkt_buffer = NULL;
ring_info->pkt_buffer_size = 0;
}