[PATCH v2] rdma/siw: Fix a use after free in siw_alloc_mr

[PATCH v2] 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).

My patch moves "mr->mem = mem" behind the if (xa_alloc_cyclic(..)<0) {}
section, to avoid the uaf.

Fixes: 2251334dcac9e ("rdma/siw: application buffer management")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
---
 drivers/infiniband/sw/siw/siw_mem.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c
index 34a910cf0edb..96b38cfbb513 100644
--- a/drivers/infiniband/sw/siw/siw_mem.c
+++ b/drivers/infiniband/sw/siw/siw_mem.c
@@ -106,8 +106,6 @@ int siw_mr_add_mem(struct siw_mr *mr, struct ib_pd *pd, void *mem_obj,
 	mem->perms = rights & IWARP_ACCESS_MASK;
 	kref_init(&mem->ref);
 
-	mr->mem = mem;
-
 	get_random_bytes(&next, 4);
 	next &= 0x00ffffff;
 
@@ -116,6 +114,8 @@ int siw_mr_add_mem(struct siw_mr *mr, struct ib_pd *pd, void *mem_obj,
 		kfree(mem);
 		return -ENOMEM;
 	}
+
+	mr->mem = mem;
 	/* Set the STag index part */
 	mem->stag = id << 8;
 	mr->base_mr.lkey = mr->base_mr.rkey = mem->stag;
-- 
2.25.1

Re: [PATCH v2] rdma/siw: Fix a use after free in siw_alloc_mr

[Leon Romanovsky]

On Sun, Apr 25, 2021 at 06:16:47PM -0700, Lv Yunlong wrote:
> Our code analyzer reported a uaf.

Can you please share more details about this "code analyzer"?

Thanks

> 
> 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).
> 
> My patch moves "mr->mem = mem" behind the if (xa_alloc_cyclic(..)<0) {}
> section, to avoid the uaf.
> 
> Fixes: 2251334dcac9e ("rdma/siw: application buffer management")
> Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
> ---
>  drivers/infiniband/sw/siw/siw_mem.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c
> index 34a910cf0edb..96b38cfbb513 100644
> --- a/drivers/infiniband/sw/siw/siw_mem.c
> +++ b/drivers/infiniband/sw/siw/siw_mem.c
> @@ -106,8 +106,6 @@ int siw_mr_add_mem(struct siw_mr *mr, struct ib_pd *pd, void *mem_obj,
>  	mem->perms = rights & IWARP_ACCESS_MASK;
>  	kref_init(&mem->ref);
>  
> -	mr->mem = mem;
> -
>  	get_random_bytes(&next, 4);
>  	next &= 0x00ffffff;
>  
> @@ -116,6 +114,8 @@ int siw_mr_add_mem(struct siw_mr *mr, struct ib_pd *pd, void *mem_obj,
>  		kfree(mem);
>  		return -ENOMEM;
>  	}
> +
> +	mr->mem = mem;
>  	/* Set the STag index part */
>  	mem->stag = id << 8;
>  	mr->base_mr.lkey = mr->base_mr.rkey = mem->stag;
> -- 
> 2.25.1
> 
> 

Re: Re: [PATCH v2] 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: 2021-04-26 13:08:50 (星期一)
> 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 v2] rdma/siw: Fix a use after free in siw_alloc_mr
> 
> On Sun, Apr 25, 2021 at 06:16:47PM -0700, Lv Yunlong wrote:
> > Our code analyzer reported a uaf.
> 
> Can you please share more details about this "code analyzer"?
> 
> Thanks
> 
> > 
> > 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).
> > 
> > My patch moves "mr->mem = mem" behind the if (xa_alloc_cyclic(..)<0) {}
> > section, to avoid the uaf.
> > 
> > Fixes: 2251334dcac9e ("rdma/siw: application buffer management")
> > Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
> > ---
> >  drivers/infiniband/sw/siw/siw_mem.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/infiniband/sw/siw/siw_mem.c b/drivers/infiniband/sw/siw/siw_mem.c
> > index 34a910cf0edb..96b38cfbb513 100644
> > --- a/drivers/infiniband/sw/siw/siw_mem.c
> > +++ b/drivers/infiniband/sw/siw/siw_mem.c
> > @@ -106,8 +106,6 @@ int siw_mr_add_mem(struct siw_mr *mr, struct ib_pd *pd, void *mem_obj,
> >  	mem->perms = rights & IWARP_ACCESS_MASK;
> >  	kref_init(&mem->ref);
> >  
> > -	mr->mem = mem;
> > -
> >  	get_random_bytes(&next, 4);
> >  	next &= 0x00ffffff;
> >  
> > @@ -116,6 +114,8 @@ int siw_mr_add_mem(struct siw_mr *mr, struct ib_pd *pd, void *mem_obj,
> >  		kfree(mem);
> >  		return -ENOMEM;
> >  	}
> > +
> > +	mr->mem = mem;
> >  	/* Set the STag index part */
> >  	mem->stag = id << 8;
> >  	mr->base_mr.lkey = mr->base_mr.rkey = mem->stag;
> > -- 
> > 2.25.1
> > 
> > 

Yes, i would like to share some details about it although it still has no name.
We designed this analzyer by adopt a deep learning model to recognize the
memory allocation and deallocation in kernel first. And then use Clang Static
Analyzer to scan the kernel code.

Re: [PATCH v2] rdma/siw: Fix a use after free in siw_alloc_mr

[Bernard Metzler]

-----"Lv Yunlong" <lyl2019@mail.ustc.edu.cn> wrote: -----

>To: bmt@zurich.ibm.com, dledford@redhat.com, jgg@ziepe.ca
>From: "Lv Yunlong" <lyl2019@mail.ustc.edu.cn>
>Date: 04/26/2021 03:17AM
>Cc: linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, "Lv
>Yunlong" <lyl2019@mail.ustc.edu.cn>
>Subject: [EXTERNAL] [PATCH v2] rdma/siw: Fix a use after free in
>siw_alloc_mr
>
>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).
>
>My patch moves "mr->mem = mem" behind the if (xa_alloc_cyclic(..)<0)
>{}
>section, to avoid the uaf.
>
>Fixes: 2251334dcac9e ("rdma/siw: application buffer management")
>Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
>---
> drivers/infiniband/sw/siw/siw_mem.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/drivers/infiniband/sw/siw/siw_mem.c
>b/drivers/infiniband/sw/siw/siw_mem.c
>index 34a910cf0edb..96b38cfbb513 100644
>--- a/drivers/infiniband/sw/siw/siw_mem.c
>+++ b/drivers/infiniband/sw/siw/siw_mem.c
>@@ -106,8 +106,6 @@ int siw_mr_add_mem(struct siw_mr *mr, struct
>ib_pd *pd, void *mem_obj,
> 	mem->perms = rights & IWARP_ACCESS_MASK;
> 	kref_init(&mem->ref);
> 
>-	mr->mem = mem;
>-
> 	get_random_bytes(&next, 4);
> 	next &= 0x00ffffff;
> 
>@@ -116,6 +114,8 @@ int siw_mr_add_mem(struct siw_mr *mr, struct
>ib_pd *pd, void *mem_obj,
> 		kfree(mem);
> 		return -ENOMEM;
> 	}
>+
>+	mr->mem = mem;
> 	/* Set the STag index part */
> 	mem->stag = id << 8;
> 	mr->base_mr.lkey = mr->base_mr.rkey = mem->stag;
>-- 
>2.25.1
>
>
>
Lv Yunlong, many thanks for catching, and thanks to
Leon for improving it.

Reviewed-by: Bernard Metzler <bmt@zurich.ihm.com>

Re: [PATCH v2] rdma/siw: Fix a use after free in siw_alloc_mr

[Jason Gunthorpe]

On Sun, Apr 25, 2021 at 06:16:47PM -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).
> 
> My patch moves "mr->mem = mem" behind the if (xa_alloc_cyclic(..)<0) {}
> section, to avoid the uaf.
> 
> Fixes: 2251334dcac9e ("rdma/siw: application buffer management")
> Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
> Reviewed-by: Bernard Metzler <bmt@zurich.ihm.com>
> ---
>  drivers/infiniband/sw/siw/siw_mem.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

Applied to for-next, thanks

Jason