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([2405:201:682f:383f:4ec4:3b70:556f:d77f]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3119d5cf176sm13391345eec.12.2026.07.09.19.46.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 09 Jul 2026 19:46:44 -0700 (PDT) From: Deepanshu Kartikey To: johannes@sipsolutions.net Cc: linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, Deepanshu Kartikey , syzbot+cc867e537e4bd36f69bb@syzkaller.appspotmail.com Subject: [PATCH] wifi: cfg80211: validate IEs in cfg80211_wext_siwgenie() Date: Fri, 10 Jul 2026 08:16:37 +0530 Message-ID: <20260710024637.16729-1-kartikey406@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Syzkaller reported a KASAN slab-out-of-bounds read in skip_ie() and a fortify memcpy panic in cfg80211_sme_get_conn_ies(). The KASAN allocation trace shows that a malformed IE buffer is stored via SIOCSIWGENIE (cfg80211_wext_siwgenie()) without any validation. The crash trace shows that a subsequent SIOCSIWESSID triggers a connection attempt which calls cfg80211_sme_get_conn_ies() to process the stored IE buffer, causing: - An out-of-bounds read in skip_ie() which reads ies[pos+1] (the length byte) past the end of the 1-byte buffer. - An integer underflow in the memcpy size argument when offs returned by ieee80211_ie_split() exceeds ies_len, causing unsigned subtraction to wrap to SIZE_MAX and triggering a fortify panic. Fix this by validating the IE buffer in cfg80211_wext_siwgenie() before storing it. Add cfg80211_validate_ies() which walks the buffer and verifies every element has at least 2 bytes (type + length) and sufficient data bytes as indicated by its length field. Return -EINVAL if validation fails. Reported-by: syzbot+cc867e537e4bd36f69bb@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3Dcc867e537e4bd36f69bb Tested-by: syzbot+cc867e537e4bd36f69bb@syzkaller.appspotmail.com Signed-off-by: Deepanshu Kartikey --- include/net/cfg80211.h | 1 + net/wireless/util.c | 16 ++++++++++++++++ net/wireless/wext-sme.c | 2 ++ 3 files changed, 19 insertions(+) diff --git a/include/net/cfg80211.h b/include/net/cfg80211.h index 8188ad200de5..32cef926f8a4 100644 --- a/include/net/cfg80211.h +++ b/include/net/cfg80211.h @@ -10992,4 +10992,5 @@ void cfg80211_incumbent_signal_notify(struct wiphy = *wiphy, u32 signal_interference_bitmap, gfp_t gfp); =20 +bool cfg80211_validate_ies(const u8 *ies, size_t ies_len); #endif /* __NET_CFG80211_H */ diff --git a/net/wireless/util.c b/net/wireless/util.c index 24527bf321b2..a685020c8efc 100644 --- a/net/wireless/util.c +++ b/net/wireless/util.c @@ -3083,3 +3083,19 @@ bool cfg80211_wdev_channel_allowed(struct wireless_d= ev *wdev, return false; } EXPORT_SYMBOL(cfg80211_wdev_channel_allowed); + +bool cfg80211_validate_ies(const u8 *ies, size_t ies_len) +{ + size_t pos =3D 0; + + while (pos < ies_len) { + if (pos + 2 > ies_len) + return false; + if (pos + 2 + ies[pos + 1] > ies_len) + return false; + pos +=3D 2 + ies[pos + 1]; + } + + return true; +} +EXPORT_SYMBOL(cfg80211_validate_ies); diff --git a/net/wireless/wext-sme.c b/net/wireless/wext-sme.c index 573b6b15a446..3e9b071f6d66 100644 --- a/net/wireless/wext-sme.c +++ b/net/wireless/wext-sme.c @@ -319,6 +319,8 @@ int cfg80211_wext_siwgenie(struct net_device *dev, return 0; =20 if (ie_len) { + if (!cfg80211_validate_ies(extra, ie_len)) + return -EINVAL; ie =3D kmemdup(extra, ie_len, GFP_KERNEL); if (!ie) return -ENOMEM; --=20 2.43.0