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@xxxxxxxxxx>
> 发送时间: 2021-04-25 21:49:36 (星期日)
> 收件人: "Lv Yunlong" <lyl2019@xxxxxxxxxxxxxxxx>
> 抄送: bmt@xxxxxxxxxxxxxx, dledford@xxxxxxxxxx, jgg@xxxxxxxx, linux-rdma@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
> 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@xxxxxxxxxxxxxxxx>
> > ---
> >  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.