From: "Bernard Metzler" <BMT@zurich.ibm.com>
To: "Lv Yunlong" <lyl2019@mail.ustc.edu.cn>
Cc: "dledford" <dledford@redhat.com>, "jgg" <jgg@ziepe.ca>,
"linux-rdma" <linux-rdma@vger.kernel.org>,
"linux-kernel" <linux-kernel@vger.kernel.org>,
leon@kernel.org
Subject: Re: [PATCH v2] rdma/siw: Fix a use after free in siw_alloc_mr
Date: Mon, 26 Apr 2021 07:26:45 +0000 [thread overview]
Message-ID: <OFEDD7FB92.558D79F3-ON002586C3.0028E6C4-002586C3.0028E6CD@notes.na.collabserv.com> (raw)
In-Reply-To: <20210426011647.3561-1-lyl2019@mail.ustc.edu.cn>
-----"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>
next prev parent reply other threads:[~2021-04-26 7:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-26 1:16 [PATCH v2] rdma/siw: Fix a use after free in siw_alloc_mr Lv Yunlong
2021-04-26 5:08 ` Leon Romanovsky
2021-04-26 9:26 ` lyl2019
2021-04-26 7:26 ` Bernard Metzler [this message]
2021-04-27 18:31 ` Jason Gunthorpe
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