From patchwork Wed Feb 12 08:32:03 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wentao Liang X-Patchwork-Id: 13971367 Received: from cstnet.cn (smtp84.cstnet.cn [159.226.251.84]) (using TLSv1.2 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4A3D91DED5F; Wed, 12 Feb 2025 08:32:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=159.226.251.84 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739349152; cv=none; b=grSQeJZvJsLTGgbzBGcQrX47sWt33SZu0zfVBpgZcbNH8bnhQSyA/epFXlyJbUTvI0EuNiin2GnZmucWthaAY6Mkltzkxw2UYnjPSDqBmu9cEB8KoGAz/DCdDwN7vkW1h1JCkmcV7DyfNH01eSRrpBPnimSREQGOOL2aiDaoXEA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739349152; c=relaxed/simple; bh=M6WO1IkI0Q7T3bIAJj97I6HVMTsXJ9vlKr3NrrCq6kM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Q4GXorLIVfx9U7ey0u28jPyJ0BD76M6t5yN4izdOC8El/0eTd4mB0tSRrQz7FJtTEqZ6bi3OxqY9AwNMDRADaDFZwt70kT/WYbrk0C0ziEyf8CU1yjPyllhdT+HOd7/6XFkQgJaB5HMSLwz1ZZNxGU3GyXVv9r3qn0caavdXy6I= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn; spf=pass smtp.mailfrom=iscas.ac.cn; arc=none smtp.client-ip=159.226.251.84 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=iscas.ac.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iscas.ac.cn Received: from localhost.localdomain (unknown [124.16.141.245]) by APP-05 (Coremail) with SMTP id zQCowAAnkMmUXKxnuhRoDA--.44357S2; Wed, 12 Feb 2025 16:32:22 +0800 (CST) From: Wentao Liang To: tj@kernel.org, josef@toxicpanda.com, axboe@kernel.dk Cc: cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Wentao Liang , stable@vger.kernel.org Subject: [PATCH] block: Check blkg_to_lat return value to avoid NULL dereference Date: Wed, 12 Feb 2025 16:32:03 +0800 Message-ID: <20250212083203.1030-1-vulab@iscas.ac.cn> X-Mailer: git-send-email 2.42.0.windows.2 Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: zQCowAAnkMmUXKxnuhRoDA--.44357S2 X-Coremail-Antispam: 1UD129KBjvJXoW7ZrWDZrykZry8JF4DXF1xGrg_yoW8XF1rpa 18urZFvay5Gw47XF18Ka1rCryrCr4UKFyUCFZ5Aa4FkF1IgF4rtF10vF10yFWrAFWUCrs8 Jr1UtFZYvr45C37anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUkl14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26r4j6ryUM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4j 6F4UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E14v26rxl6s 0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7xfMcIj6xII jxv20xvE14v26r1Y6r17McIj6I8E87Iv67AKxVW8JVWxJwAm72CE4IkC6x0Yz7v_Jr0_Gr 1lF7xvr2IYc2Ij64vIr41lF7I21c0EjII2zVCS5cI20VAGYxC7MxkF7I0En4kS14v26r12 6r1DMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI 0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y 0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxV WUJVW8JwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1l IxAIcVC2z280aVCY1x0267AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7VUjMqcUUUUU U== X-CM-SenderInfo: pyxotu46lvutnvoduhdfq/1tbiDAULA2esWj4JCwAAss The function blkg_to_lat() may return NULL if the blkg is not associated with an iolatency group. In iolatency_set_min_lat_nsec() and iolatency_pd_init(), the return values are not checked, leading to potential NULL pointer dereferences. This patch adds checks for the return values of blkg_to_lat and let it returns early if it is NULL, preventing the NULL pointer dereference. Fixes: d70675121546 ("block: introduce blk-iolatency io controller") Cc: stable@vger.kernel.org # 4.19+ Signed-off-by: Wentao Liang --- block/blk-iolatency.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c index ebb522788d97..398f0a1747c4 100644 --- a/block/blk-iolatency.c +++ b/block/blk-iolatency.c @@ -787,6 +787,8 @@ static int blk_iolatency_init(struct gendisk *disk) static void iolatency_set_min_lat_nsec(struct blkcg_gq *blkg, u64 val) { struct iolatency_grp *iolat = blkg_to_lat(blkg); + if (!iolat) + return; struct blk_iolatency *blkiolat = iolat->blkiolat; u64 oldval = iolat->min_lat_nsec; @@ -1013,6 +1015,8 @@ static void iolatency_pd_init(struct blkg_policy_data *pd) */ if (blkg->parent && blkg_to_pd(blkg->parent, &blkcg_policy_iolatency)) { struct iolatency_grp *parent = blkg_to_lat(blkg->parent); + if (!parent) + return; atomic_set(&iolat->scale_cookie, atomic_read(&parent->child_lat.scale_cookie)); } else {