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Message-ID: <39279ba0ced207f484b664fe5364fa4ee6271cfb.camel@redhat.com>
Date: Thu, 23 Jun 2022 11:42:43 +0200
From: Paolo Abeni <pabeni@...hat.com>
To: Hangyu Hua <hbh25y@...il.com>, krzysztof.kozlowski@...aro.org,
sameo@...ux.intel.com, christophe.ricard@...il.com
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nfc: st21nfca: fix possible double free in
st21nfca_im_recv_dep_res_cb()
On Wed, 2022-06-22 at 14:51 +0800, Hangyu Hua wrote:
> nfc_tm_data_received will free skb internally when it fails. There is no
> need to free skb in st21nfca_im_recv_dep_res_cb again.
>
> Fix this by setting skb to NULL when nfc_tm_data_received fails.
>
> Fixes: 1892bf844ea0 ("NFC: st21nfca: Adding P2P support to st21nfca in Initiator & Target mode")
> Signed-off-by: Hangyu Hua <hbh25y@...il.com>
> ---
> drivers/nfc/st21nfca/dep.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/nfc/st21nfca/dep.c b/drivers/nfc/st21nfca/dep.c
> index 1ec651e31064..07ac5688011c 100644
> --- a/drivers/nfc/st21nfca/dep.c
> +++ b/drivers/nfc/st21nfca/dep.c
> @@ -594,7 +594,8 @@ static void st21nfca_im_recv_dep_res_cb(void *context, struct sk_buff *skb,
> ST21NFCA_NFC_DEP_PFB_PNI(dep_res->pfb + 1);
> size++;
> skb_pull(skb, size);
> - nfc_tm_data_received(info->hdev->ndev, skb);
> + if (nfc_tm_data_received(info->hdev->ndev, skb))
> + skb = NULL;
Note that 'skb' not used (nor freed) by this function after this point:
the next 'break' statement refears to the inner switch, and land to the
execution flow to the 'return' statement a few lines below.
kfree_skb(skb) is never reached.
Paolo
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