linux-kernel - Re: [PATCH] net/mlx5e: Fix slab-out-of-bounds in mlx5_query_nic_vport_mac

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Date:   Wed, 6 Dec 2023 21:30:33 +0000
From:   Simon Horman <horms@...nel.org>
To:     Shifeng Li <lishifeng1992@....com>
Cc:     Shifeng Li <lishifeng@...gfor.com.cn>, saeedm@...dia.com,
        leon@...nel.org, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, ogerlitz@...lanox.com,
        netdev@...r.kernel.org, linux-rdma@...r.kernel.org,
        linux-kernel@...r.kernel.org, dinghui@...gfor.com.cn
Subject: Re: [PATCH] net/mlx5e: Fix slab-out-of-bounds in
 mlx5_query_nic_vport_mac_list()

On Mon, Dec 04, 2023 at 10:30:14AM +0800, Shifeng Li wrote:
> On 2023/12/4 1:50, Simon Horman wrote:
> > On Thu, Nov 30, 2023 at 01:46:56AM -0800, Shifeng Li wrote:
> > > Out_sz that the size of out buffer is calculated using query_nic_vport
> > > _context_in structure when driver query the MAC list. However query_nic
> > > _vport_context_in structure is smaller than query_nic_vport_context_out.
> > > When allowed_list_size is greater than 96, calling ether_addr_copy() will
> > > trigger an slab-out-of-bounds.
> > > 
> > > [ 1170.055866] BUG: KASAN: slab-out-of-bounds in mlx5_query_nic_vport_mac_list+0x481/0x4d0 [mlx5_core]
> > > [ 1170.055869] Read of size 4 at addr ffff88bdbc57d912 by task kworker/u128:1/461
> > > [ 1170.055870]
> > > [ 1170.055932] Workqueue: mlx5_esw_wq esw_vport_change_handler [mlx5_core]
> > > [ 1170.055936] Call Trace:
> > > [ 1170.055949]  dump_stack+0x8b/0xbb
> > > [ 1170.055958]  print_address_description+0x6a/0x270
> > > [ 1170.055961]  kasan_report+0x179/0x2c0
> > > [ 1170.056061]  mlx5_query_nic_vport_mac_list+0x481/0x4d0 [mlx5_core]
> > > [ 1170.056162]  esw_update_vport_addr_list+0x2c5/0xcd0 [mlx5_core]
> > > [ 1170.056257]  esw_vport_change_handle_locked+0xd08/0x1a20 [mlx5_core]
> > > [ 1170.056377]  esw_vport_change_handler+0x6b/0x90 [mlx5_core]
> > > [ 1170.056381]  process_one_work+0x65f/0x12d0
> > > [ 1170.056383]  worker_thread+0x87/0xb50
> > > [ 1170.056390]  kthread+0x2e9/0x3a0
> > > [ 1170.056394]  ret_from_fork+0x1f/0x40
> > > 
> > > Fixes: e16aea2744ab ("net/mlx5: Introduce access functions to modify/query vport mac lists")
> > > Cc: Ding Hui <dinghui@...gfor.com.cn>
> > > Signed-off-by: Shifeng Li <lishifeng@...gfor.com.cn>
> > 
> > Hi,
> > 
> > I am unsure how you calculated the 96 figure above.
> > But in any case I agree that the cited patch introduced
> > the mismatch that you describe.
> > 
> out_sz = MLX5_ST_SZ_BYTES(query_nic_vport_context_in) + req_list_size * MLX5_ST_SZ_BYTES(mac_address_layout)
>        = 0x80/8 + 128 * 0x40/8 = 0x410 (bytes)
> 
> nic_vport_ctx = MLX5_ADDR_OF(query_nic_vport_context_out, out, nic_vport_context)
>               = 0x880/8 = 0x110 (bytes)
> mac_addr = MLX5_ADDR_OF(nic_vport_context, nic_vport_ctx, current_uc_mac_address[96]) + 2
>          = 0x110 + 96 * 8 + 2
>          = 0x412 (bytes)
> 
> When i is 96,  the mac_addr offset is 0x412 but the out_sz is 0x410.
> And that will trigger an slab-out-of-bounds.

Thanks for the clarification, this looks good to me.

> > Reviewed-by: Simon Horman <horms@...nel.org>