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Tue, 23 Jun 2026 22:33:00 -0700 (PDT) Received: from localhost.localdomain ([192.197.201.174]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-30c1ba1c32csm22955775eec.6.2026.06.23.22.32.58 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 23 Jun 2026 22:32:59 -0700 (PDT) From: hewei-gikaku To: Christian Lamparter Cc: linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org, HE WEI , syzbot+5c1ca6ccaa1215781cac@syzkaller.appspotmail.com Subject: [PATCH] wifi: carl9170: bail out on invalid command response to fix stack-out-of-bounds write Date: Wed, 24 Jun 2026 14:32:45 +0900 Message-ID: <20260624053246.74617-1-skyexpoc@gmail.com> X-Mailer: git-send-email 2.54.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: HE WEI (ギカク) carl9170_cmd_callback() copies a command response coming from the USB device into ar->readbuf using the device-reported length: memcpy(ar->readbuf, buffer + 4, len - 4); ar->readbuf points at the buffer supplied by the caller of carl9170_exec_cmd(), which is frequently an on-stack buffer sized to the expected response length (ar->readlen). The preceding sanity check only emits a warning and schedules a restart when ar->readlen != len - 4; it does not stop processing, so the memcpy() still runs with the attacker-controlled length. A malicious or malfunctioning AR9170 USB device can therefore answer a pending command with an over-sized response and overflow ar->readbuf, as reported by syzbot: BUG: KASAN: stack-out-of-bounds Write in carl9170_handle_command_response The comment in that branch already documents the intended behaviour ("Do not complete. The command times out, and we get a stack trace from there."), but the return statement was missing. Return after carl9170_restart() so an over-/under-sized response is neither copied into ar->readbuf nor completed; carl9170_exec_cmd() then times out and clears readbuf in its error path. Reported-by: syzbot+5c1ca6ccaa1215781cac@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=5c1ca6ccaa1215781cac Fixes: a84fab3cbfdc ("carl9170: 802.11 rx/tx processing and usb backend") Signed-off-by: HE WEI (ギカク) --- drivers/net/wireless/ath/carl9170/rx.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/wireless/ath/carl9170/rx.c b/drivers/net/wireless/ath/carl9170/rx.c --- a/drivers/net/wireless/ath/carl9170/rx.c +++ b/drivers/net/wireless/ath/carl9170/rx.c @@ -145,6 +145,7 @@ static void carl9170_cmd_callback(struct ar9170 *ar, u32 len, void *buffer) * and we get a stack trace from there. */ carl9170_restart(ar, CARL9170_RR_INVALID_RSP); + return; } spin_lock(&ar->cmd_lock); -- 2.43.0