linux-kernel - Re: [PATCH] wifi: brcm80211: handle pmk

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Message-ID: <87166784-79ab-4eb4-ad1e-af4bc31757b7@broadcom.com>
Date: Tue, 27 Feb 2024 12:21:31 +0100
From: Arend van Spriel <arend.vanspriel@...adcom.com>
To: Duoming Zhou <duoming@....edu.cn>, linux-kernel@...r.kernel.org
Cc: brcm80211-dev-list.pdl@...adcom.com, brcm80211@...ts.linux.dev,
 linux-wireless@...r.kernel.org, justinstitt@...gle.com, john@...ping.me.uk,
 quic_alokad@...cinc.com, marcan@...can.st, johannes.berg@...el.com,
 linus.walleij@...aro.org, kvalo@...nel.org, Joe Perches <joe@...ches.com>
Subject: Re: [PATCH] wifi: brcm80211: handle pmk_op allocation failure

On 2/27/2024 9:06 AM, Duoming Zhou wrote:
> The kzalloc() in brcmf_pmksa_v3_op() will return null if the
> physical memory has run out. As a result, if we dereference
> the null value, the null pointer dereference bug will happen.
> 
> Return -ENOMEM from brcmf_pmksa_v3_op() if kzalloc() fails
> for pmk_op.

NAK (see below)

Also this issue was reported earlier by Joe Perches. Not sure if he 
wants to be mentioned as such.

> Fixes: a96202acaea4 ("wifi: brcmfmac: cfg80211: Add support for PMKID_V3 operations")
> Signed-off-by: Duoming Zhou <duoming@....edu.cn>
> ---
>   drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> index 28d6a30cc01..3b420b33188 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
> @@ -4322,6 +4322,10 @@ brcmf_pmksa_v3_op(struct brcmf_if *ifp, struct cfg80211_pmksa *pmksa,
>   	int ret;
>   
>   	pmk_op = kzalloc(sizeof(*pmk_op), GFP_KERNEL);
> +	if (!pmk_op) {
> +		ret = -ENOMEM;
> +		goto out;
> +	}

There is really no need to introduce a new label for this. Although you 
can kfree() a NULL pointer there is no need to do so when you know 
already it is NULL. Just return -ENOMEM and be done with it.

Regards,
Arend

>   	pmk_op->version = cpu_to_le16(BRCMF_PMKSA_VER_3);
>   
>   	if (!pmksa) {
> @@ -4340,6 +4344,7 @@ brcmf_pmksa_v3_op(struct brcmf_if *ifp, struct cfg80211_pmksa *pmksa,
>   	pmk_op->length = cpu_to_le16(length);
>   
>   	ret = brcmf_fil_iovar_data_set(ifp, "pmkid_info", pmk_op, sizeof(*pmk_op));
> +out:
>   	kfree(pmk_op);
>   	return ret;
>   }

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