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    Subject[PATCH AUTOSEL 4.14 079/108] vfio/pci: fix memory leaks of eventfd ctx
    Date
    From: Qian Cai <cai@lca.pw>

    [ Upstream commit 1518ac272e789cae8c555d69951b032a275b7602 ]

    Finished a qemu-kvm (-device vfio-pci,host=0001:01:00.0) triggers a few
    memory leaks after a while because vfio_pci_set_ctx_trigger_single()
    calls eventfd_ctx_fdget() without the matching eventfd_ctx_put() later.
    Fix it by calling eventfd_ctx_put() for those memory in
    vfio_pci_release() before vfio_device_release().

    unreferenced object 0xebff008981cc2b00 (size 128):
    comm "qemu-kvm", pid 4043, jiffies 4294994816 (age 9796.310s)
    hex dump (first 32 bytes):
    01 00 00 00 6b 6b 6b 6b 00 00 00 00 ad 4e ad de ....kkkk.....N..
    ff ff ff ff 6b 6b 6b 6b ff ff ff ff ff ff ff ff ....kkkk........
    backtrace:
    [<00000000917e8f8d>] slab_post_alloc_hook+0x74/0x9c
    [<00000000df0f2aa2>] kmem_cache_alloc_trace+0x2b4/0x3d4
    [<000000005fcec025>] do_eventfd+0x54/0x1ac
    [<0000000082791a69>] __arm64_sys_eventfd2+0x34/0x44
    [<00000000b819758c>] do_el0_svc+0x128/0x1dc
    [<00000000b244e810>] el0_sync_handler+0xd0/0x268
    [<00000000d495ef94>] el0_sync+0x164/0x180
    unreferenced object 0x29ff008981cc4180 (size 128):
    comm "qemu-kvm", pid 4043, jiffies 4294994818 (age 9796.290s)
    hex dump (first 32 bytes):
    01 00 00 00 6b 6b 6b 6b 00 00 00 00 ad 4e ad de ....kkkk.....N..
    ff ff ff ff 6b 6b 6b 6b ff ff ff ff ff ff ff ff ....kkkk........
    backtrace:
    [<00000000917e8f8d>] slab_post_alloc_hook+0x74/0x9c
    [<00000000df0f2aa2>] kmem_cache_alloc_trace+0x2b4/0x3d4
    [<000000005fcec025>] do_eventfd+0x54/0x1ac
    [<0000000082791a69>] __arm64_sys_eventfd2+0x34/0x44
    [<00000000b819758c>] do_el0_svc+0x128/0x1dc
    [<00000000b244e810>] el0_sync_handler+0xd0/0x268
    [<00000000d495ef94>] el0_sync+0x164/0x180

    Signed-off-by: Qian Cai <cai@lca.pw>
    Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/vfio/pci/vfio_pci.c | 4 ++++
    1 file changed, 4 insertions(+)

    diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
    index 550ab7707b57..b7733d3c06de 100644
    --- a/drivers/vfio/pci/vfio_pci.c
    +++ b/drivers/vfio/pci/vfio_pci.c
    @@ -397,6 +397,10 @@ static void vfio_pci_release(void *device_data)
    if (!(--vdev->refcnt)) {
    vfio_spapr_pci_eeh_release(vdev->pdev);
    vfio_pci_disable(vdev);
    + if (vdev->err_trigger)
    + eventfd_ctx_put(vdev->err_trigger);
    + if (vdev->req_trigger)
    + eventfd_ctx_put(vdev->req_trigger);
    }

    mutex_unlock(&driver_lock);
    --
    2.25.1
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