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SubjectRe: [PATCH] rdma/siw: Fix a use after free in siw_alloc_mr
On Sun, Apr 25, 2021 at 06:20:01AM -0700, Lv Yunlong wrote:
> Our code analyzer reported a uaf.
>
> In siw_alloc_mr, it calls siw_mr_add_mem(mr,..). In the implementation
> of siw_mr_add_mem(), mem is assigned to mr->mem and then mem is freed
> via kfree(mem) if xa_alloc_cyclic() failed. Here, mr->mem still point
> to a freed object. After, the execution continue up to the err_out branch
> of siw_alloc_mr, and the freed mr->mem is used in siw_mr_drop_mem(mr).
>
> Fixes: 2251334dcac9e ("rdma/siw: application buffer management")
> Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
> ---
> drivers/infiniband/sw/siw/siw_mem.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c
> index 34a910cf0edb..3bde3b6fca05 100644
> --- a/drivers/infiniband/sw/siw/siw_mem.c
> +++ b/drivers/infiniband/sw/siw/siw_mem.c
> @@ -114,6 +114,7 @@ int siw_mr_add_mem(struct siw_mr *mr, struct ib_pd *pd, void *mem_obj,
> if (xa_alloc_cyclic(&sdev->mem_xa, &id, mem, limit, &next,
> GFP_KERNEL) < 0) {
> kfree(mem);
> + mr->mem = NULL;
> return -ENOMEM;
> }

Please move "mr->mem = mem;" assignment to be here, after if (...) {} section.

Thanks

> /* Set the STag index part */
> --
> 2.25.1
>
>

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