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Message-ID: <YfPDJaPJ89vTuBXA@kroah.com>
Date: Fri, 28 Jan 2022 11:19:17 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Zhou Qingyang <zhou1615@....edu>
Cc: kjlu@....edu, Arend van Spriel <aspriel@...il.com>,
Franky Lin <franky.lin@...adcom.com>,
Hante Meuleman <hante.meuleman@...adcom.com>,
Chi-hsien Lin <chi-hsien.lin@...ineon.com>,
Wright Feng <wright.feng@...ineon.com>,
Chung-hsien Hsu <chung-hsien.hsu@...ineon.com>,
Kalle Valo <kvalo@...nel.org>,
"David S. Miller" <davem@...emloft.net>,
Jakub Kicinski <kuba@...nel.org>,
Len Baker <len.baker@....com>,
"Gustavo A. R. Silva" <gustavoars@...nel.org>,
Shawn Guo <shawn.guo@...aro.org>,
Hans deGoede <hdegoede@...hat.com>,
Matthias Brugger <mbrugger@...e.com>,
linux-wireless@...r.kernel.org,
brcm80211-dev-list.pdl@...adcom.com,
SHA-cyfmac-dev-list@...ineon.com, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] brcmfmac: Fix a NULL pointer dereference in
brcmf_of_probe()
On Tue, Jan 25, 2022 at 12:50:46AM +0800, Zhou Qingyang wrote:
> In brcmf_of_probe(), the return value of devm_kzalloc() is assigned to
> board_type and there is a dereference of it in strcpy() right after
> that. devm_kzalloc() could return NULL on failure of allocation, which
> could lead to NULL pointer dereference.
>
> Fix this bug by adding a NULL check of board_type.
>
> This bug was found by a static analyzer.
>
> Builds with 'make allyesconfig' show no new warnings,
> and our static analyzer no longer warns about this code
>
> Fixes: 29e354ebeeec ("brcmfmac: Transform compatible string for FW loading")
> Signed-off-by: Zhou Qingyang <zhou1615@....edu>
> ---
> The analysis employs differential checking to identify inconsistent
> security operations (e.g., checks or kfrees) between two code paths
> and confirms that the inconsistent operations are not recovered in the
> current function or the callers, so they constitute bugs.
>
> Note that, as a bug found by static analysis, it can be a false
> positive or hard to trigger. Multiple researchers have cross-reviewed
> the bug.
>
> drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> index 513c7e6421b2..535e8ddeab8d 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/of.c
> @@ -80,6 +80,8 @@ void brcmf_of_probe(struct device *dev, enum brcmf_bus_type bus_type,
> /* get rid of '/' in the compatible string to be able to find the FW */
> len = strlen(tmp) + 1;
> board_type = devm_kzalloc(dev, len, GFP_KERNEL);
> + if (!board_type)
> + return;
> strscpy(board_type, tmp, len);
> for (i = 0; i < board_type[i]; i++) {
> if (board_type[i] == '/')
> --
> 2.25.1
>
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