[PATCH] rdma/siw: Fix a use after free in siw_alloc_mr

[PATCH] rdma/siw: Fix a use after free in siw_alloc_mr

[Lv Yunlong]

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;
 	}
 	/* Set the STag index part */
-- 
2.25.1

Re: [PATCH] rdma/siw: Fix a use after free in siw_alloc_mr

[Leon Romanovsky]

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
> 
> 

Re: Re: [PATCH] rdma/siw: Fix a use after free in siw_alloc_mr

[lyl2019]

> -----原始邮件-----
> 发件人: "Leon Romanovsky" <leon@kernel.org>
> 发送时间: 2021-04-25 21:49:36 (星期日)
> 收件人: "Lv Yunlong" <lyl2019@mail.ustc.edu.cn>
> 抄送: bmt@zurich.ibm.com, dledford@redhat.com, jgg@ziepe.ca, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org
> 主题: Re: [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
> > 
> > 

Ok, i have modified my patch and send the PATCH v2.

Thanks for your time.