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From:   Franky Lin <franky.lin@broadcom.com>
Date:   Tue, 3 Dec 2019 10:42:20 -0800
Message-ID: <CA+8PC_ehSW=-eVC0qAbh-m+8WHwKrmbYWrhmX8w4ovGS8TVE0w@mail.gmail.com>
Subject: Re: [PATCH] brcmfmac: Fix use after free in brcmf_sdio_readframes()
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     Arend van Spriel <arend.vanspriel@broadcom.com>,
        Franky Lin <frankyl@broadcom.com>,
        Hante Meuleman <hante.meuleman@broadcom.com>,
        Chi-Hsien Lin <chi-hsien.lin@cypress.com>,
        Wright Feng <wright.feng@cypress.com>,
        Kalle Valo <kvalo@codeaurora.org>,
        Douglas Anderson <dianders@chromium.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= <rafal@milecki.pl>,
        Naveen Gupta <naveen.gupta@cypress.com>,
        "open list:BROADCOM BRCM80211 IEEE802.11n WIRELESS DRIVER" 
        <linux-wireless@vger.kernel.org>,
        "open list:BROADCOM BRCM80211 IEEE802.11n WIRELESS DRIVER" 
        <brcm80211-dev-list.pdl@broadcom.com>,
        brcm80211-dev-list <brcm80211-dev-list@cypress.com>,
        kernel-janitors@vger.kernel.org
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On Tue, Dec 3, 2019 at 1:59 AM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> The brcmu_pkt_buf_free_skb() function frees "pkt" so it leads to a
> static checker warning:
>
>     drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c:1974 brcmf_sdio_readframes()
>     error: dereferencing freed memory 'pkt'
>
> It looks like there was supposed to be a continue after we free "pkt".

Good catch!

Acked-by: Franky Lin <franky.lin@broadcom.com>

>
> Fixes: 4754fceeb9a6 ("brcmfmac: streamline SDIO read frame routine")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> Static analysis.  Not tested.
>
>  drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
> index 264ad63232f8..1dea0178832e 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c
> @@ -1935,6 +1935,7 @@ static uint brcmf_sdio_readframes(struct brcmf_sdio *bus, uint maxframes)
>                                                BRCMF_SDIO_FT_NORMAL)) {
>                                 rd->len = 0;
>                                 brcmu_pkt_buf_free_skb(pkt);
> +                               continue;
>                         }
>                         bus->sdcnt.rx_readahead_cnt++;
>                         if (rd->len != roundup(rd_new.len, 16)) {
> --
> 2.11.0
>