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    Subject[PATCH 4.14 079/496] IB/uverbs: Fix unbalanced unlock on error path for rdma_explicit_destroy
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Jason Gunthorpe <jgg@mellanox.com>

    [ Upstream commit ec6f8401c48a86809237e86878a6fac6b281118f ]

    If remove_commit fails then the lock is left locked while the uobj still
    exists. Eventually the kernel will deadlock.

    lockdep detects this and says:

    test/4221 is leaving the kernel with locks still held!
    1 lock held by test/4221:
    #0: (&ucontext->cleanup_rwsem){.+.+}, at: [<000000001e5c7523>] rdma_explicit_destroy+0x37/0x120 [ib_uverbs]

    Fixes: 4da70da23e9b ("IB/core: Explicitly destroy an object while keeping uobject")
    Signed-off-by: Leon Romanovsky <leon@kernel.org>
    Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
    Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    ---
    drivers/infiniband/core/rdma_core.c | 5 +++--
    1 file changed, 3 insertions(+), 2 deletions(-)

    --- a/drivers/infiniband/core/rdma_core.c
    +++ b/drivers/infiniband/core/rdma_core.c
    @@ -486,12 +486,13 @@ int rdma_explicit_destroy(struct ib_uobj
    ret = uobject->type->type_class->remove_commit(uobject,
    RDMA_REMOVE_DESTROY);
    if (ret)
    - return ret;
    + goto out;

    uobject->type = &null_obj_type;

    +out:
    up_read(&ucontext->cleanup_rwsem);
    - return 0;
    + return ret;
    }

    static void alloc_commit_idr_uobject(struct ib_uobject *uobj)

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