From nobody Wed Dec 17 05:48:17 2025 Received: from zg8tmja5ljk3lje4ms43mwaa.icoremail.net (zg8tmja5ljk3lje4ms43mwaa.icoremail.net [209.97.181.73]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 6E50C13C8E4; Thu, 9 May 2024 01:56:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.97.181.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715219807; cv=none; b=J6q7kApJYeo0QP1mK2qxqxd7cOC8W6WBzH0GKvuUbJAc8/YBRrC1CSsv1h5jdVV0Nmn0UUblRv8LV/cOHa1bnrvQUk7SkwUVd5JV3HxqIEfJRP029RGQ0s5ud0mxaG2reZ4YVe9HZZu9Kzj1/DS9Cf1uzFfhpxgetUBDl5FeWlA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715219807; c=relaxed/simple; bh=pAMA04ifScVk7DtVBKC9aemVsE2UnpKI1hMezSYxt8I=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References; b=mbT/iS08Ifxxt0alA1GpDlMX2I/d668xb5QihZMd2/1Sv1mZyVVSzHV3JD5az0AyWvtp7HxyiBHMF2hSn1vZuSDRC3RB2AUVCQpMqlmL4ALfoxGTB5igPcmPpwEzmgoVk+KowxAW7XTIT0CudpoGHI+Ngz8zT3VmvokXs3MUklQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn; spf=pass smtp.mailfrom=zju.edu.cn; arc=none smtp.client-ip=209.97.181.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=zju.edu.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zju.edu.cn Received: from ubuntu.localdomain (unknown [221.192.180.131]) by mail-app4 (Coremail) with SMTP id cS_KCgDX9rRKLTxm_0lMAA--.21121S2; Thu, 09 May 2024 09:56:29 +0800 (CST) From: Duoming Zhou To: netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-hams@vger.kernel.org, pabeni@redhat.com, kuba@kernel.org, edumazet@google.com, davem@davemloft.net, jreuter@yaina.de, dan.carpenter@linaro.org, Duoming Zhou Subject: [PATCH net v6 2/3] ax25: Fix reference count leak issues of ax25_dev Date: Thu, 9 May 2024 09:56:25 +0800 Message-Id: X-Mailer: git-send-email 2.17.1 In-Reply-To: References: X-CM-TRANSID: cS_KCgDX9rRKLTxm_0lMAA--.21121S2 X-Coremail-Antispam: 1UD129KBjvJXoW7ZF4rXr4Utr1rur1UtFykGrg_yoW8tFWkpF Wa9FW5ArWktr4Utr4DWr1xWr1jyryqk395CryUuF1Ikw1rX3sxJr1rtrWDXFy5GryrAF48 Xw17Xrs8ZFWkCaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9C14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4U JVW0owA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0 I7IYx2IY67AKxVWUXVWUAwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r 4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628v n2kIc2xKxwCY1x0262kKe7AKxVWUtVW8ZwCY02Avz4vE14v_KwCF04k20xvY0x0EwIxGrw CFx2IqxVCFs4IE7xkEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE 14v26r106r1rMI8E67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2 IY67AKxVWUJVWUCwCI42IY6xIIjxv20xvEc7CjxVAFwI0_Gr0_Cr1lIxAIcVCF04k26cxK x2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI 0_Gr0_Gr1UYxBIdaVFxhVjvjDU0xZFpf9x0JUL4SrUUUUU= X-CM-SenderInfo: qssqjiasttq6lmxovvfxof0/1tbiAwIQAWY7nwoGrwAKs7 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" The ax25_addr_ax25dev() and ax25_dev_device_down() exist a reference count leak issue of the object "ax25_dev". Memory leak issue in ax25_addr_ax25dev(): The reference count of the object "ax25_dev" can be increased multiple times in ax25_addr_ax25dev(). This will cause a memory leak. Memory leak issues in ax25_dev_device_down(): The reference count of ax25_dev is set to 1 in ax25_dev_device_up() and then increase the reference count when ax25_dev is added to ax25_dev_list. As a result, the reference count of ax25_dev is 2. But when the device is shutting down. The ax25_dev_device_down() drops the reference count once or twice depending on if we goto unlock_put or not, which will cause memory leak. As for the issue of ax25_addr_ax25dev(), it is impossible for one pointer to be on a list twice. So add a break in ax25_addr_ax25dev(). As for the issue of ax25_dev_device_down(), increase the reference count of ax25_dev once in ax25_dev_device_up() and decrease the reference count of ax25_dev after it is removed from the ax25_dev_list. Fixes: d01ffb9eee4a ("ax25: add refcount in ax25_dev to avoid UAF bugs") Suggested-by: Dan Carpenter Signed-off-by: Duoming Zhou --- net/ax25/ax25_dev.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/net/ax25/ax25_dev.c b/net/ax25/ax25_dev.c index 56b14d240a6..37150f766a0 100644 --- a/net/ax25/ax25_dev.c +++ b/net/ax25/ax25_dev.c @@ -39,6 +39,7 @@ ax25_dev *ax25_addr_ax25dev(ax25_address *addr) if (ax25cmp(addr, (const ax25_address *)ax25_dev->dev->dev_addr) =3D=3D = 0) { res =3D ax25_dev; ax25_dev_hold(ax25_dev); + break; } spin_unlock_bh(&ax25_dev_lock); =20 @@ -91,7 +92,6 @@ void ax25_dev_device_up(struct net_device *dev) list_add(&ax25_dev->list, &ax25_dev_list); dev->ax25_ptr =3D ax25_dev; spin_unlock_bh(&ax25_dev_lock); - ax25_dev_hold(ax25_dev); =20 ax25_register_dev_sysctl(ax25_dev); } @@ -132,7 +132,6 @@ void ax25_dev_device_down(struct net_device *dev) unlock_put: dev->ax25_ptr =3D NULL; spin_unlock_bh(&ax25_dev_lock); - ax25_dev_put(ax25_dev); netdev_put(dev, &ax25_dev->dev_tracker); ax25_dev_put(ax25_dev); } --=20 2.17.1