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Message-ID: <dd7641f326b63211c3a749341e905cca90c9e124.camel@redhat.com>
Subject: Re: [PATCH v2]  drivers: net: vmxnet3: fix possible NULL pointer
 dereference in vmxnet3_rq_cleanup()
From:   Paolo Abeni <pabeni@redhat.com>
To:     Zixuan Fu <r33s3n6@gmail.com>, doshir@vmware.com,
        pv-drivers@vmware.com, davem@davemloft.net, edumazet@google.com,
        kuba@kernel.org
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        baijiaju1990@gmail.com, TOTE Robot <oslab@tsinghua.edu.cn>
Date:   Thu, 12 May 2022 09:22:48 +0200
In-Reply-To: <20220510131727.929547-1-r33s3n6@gmail.com>
References: <20220510131727.929547-1-r33s3n6@gmail.com>
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On Tue, 2022-05-10 at 21:17 +0800, Zixuan Fu wrote:
> In vmxnet3_rq_create(), when dma_alloc_coherent() fails, 
> vmxnet3_rq_destroy() is called. It sets rq->rx_ring[i].base to NULL. Then
> vmxnet3_rq_create() returns an error to its callers mxnet3_rq_create_all()
> -> vmxnet3_change_mtu(). Then vmxnet3_change_mtu() calls 
> vmxnet3_force_close() -> dev_close() in error handling code. And the driver
> calls vmxnet3_close() -> vmxnet3_quiesce_dev() -> vmxnet3_rq_cleanup_all()
> -> vmxnet3_rq_cleanup(). In vmxnet3_rq_cleanup(), 
> rq->rx_ring[ring_idx].base is accessed, but this variable is NULL, causing
> a NULL pointer dereference.
> 
> To fix this possible bug, an if statement is added to check whether 
> rq->rx_ring[0].base is NULL in vmxnet3_rq_cleanup() and exit early if so.
> 
> The error log in our fault-injection testing is shown as follows:
> 
> [   65.220135] BUG: kernel NULL pointer dereference, address: 0000000000000008
> ...
> [   65.222633] RIP: 0010:vmxnet3_rq_cleanup_all+0x396/0x4e0 [vmxnet3]
> ...
> [   65.227977] Call Trace:
> ...
> [   65.228262]  vmxnet3_quiesce_dev+0x80f/0x8a0 [vmxnet3]
> [   65.228580]  vmxnet3_close+0x2c4/0x3f0 [vmxnet3]
> [   65.228866]  __dev_close_many+0x288/0x350
> [   65.229607]  dev_close_many+0xa4/0x480
> [   65.231124]  dev_close+0x138/0x230
> [   65.231933]  vmxnet3_force_close+0x1f0/0x240 [vmxnet3]
> [   65.232248]  vmxnet3_change_mtu+0x75d/0x920 [vmxnet3]
> ...
> 
> Reported-by: TOTE Robot <oslab@tsinghua.edu.cn>
> Signed-off-by: Zixuan Fu <r33s3n6@gmail.com>

Same remarks here, please provide a new version with a suitable fixes
tag, thanks!

Paolo