RDMA/hfi1: Fix use-after-free bug for mm struct
Under certain conditions, such as MPI_Abort, the hfi1 cleanup code may represent the last reference held on the task mm. hfi1_mmu_rb_unregister() then drops the last reference and the mm is freed before the final use in hfi1_release_user_pages(). A new task may allocate the mm structure while it is still being used, resulting in problems. One manifestation is corruption of the mmap_sem counter leading to a hang in down_write(). Another is corruption of an mm struct that is in use by another task. Fixes: 3d2a9d64 ("IB/hfi1: Ensure correct mm is used at all times") Link: https://lore.kernel.org/r/20220408133523.122165.72975.stgit@awfm-01.cornelisnetworks.com Cc: <stable@vger.kernel.org> Signed-off-by: Douglas Miller <doug.miller@cornelisnetworks.com> Signed-off-by: Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
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