linux-kernel - Re: [PATCH v2] wifi: brcm80211: handle pmk

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Date: Wed, 28 Feb 2024 06:48:14 -0800
From: Kees Cook <kees@...nel.org>
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,
 jisoo.jang@...sei.ac.kr, petr.tesarik.ext@...wei.com,
 quic_alokad@...cinc.com, hdegoede@...hat.com, keescook@...omium.org,
 johannes.berg@...el.com, kvalo@...nel.org, arend.vanspriel@...adcom.com
Subject: Re: [PATCH v2] wifi: brcm80211: handle pmk_op allocation failure



On February 27, 2024 10:34:08 PM PST, Duoming Zhou <duoming@....edu.cn> 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.
>
>Fixes: a96202acaea4 ("wifi: brcmfmac: cfg80211: Add support for PMKID_V3 operations")
>Signed-off-by: Duoming Zhou <duoming@....edu.cn>
>---
>Changes in v2:
>  - Drop the new label and just return -ENOMEM.
>
> drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c | 3 +++
> 1 file changed, 3 insertions(+)
>
>diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
>index 28d6a30cc01..7af6d6448b9 100644
>--- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
>+++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c
>@@ -4322,6 +4322,9 @@ 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;

This doesn't fix anything. It doesn't stop the execution path; it'll continue and immediately dereference the NULL pmk_op in the next line...

>+
> 	pmk_op->version = cpu_to_le16(BRCMF_PMKSA_VER_3);
> 
> 	if (!pmksa) {

-- 
Kees Cook