From nobody Thu Oct 2 03:27:32 2025 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 008DF4502F; Tue, 23 Sep 2025 07:11:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758611481; cv=none; b=f5tSwxtYd7M9ZmzKy3YVjlTsz5mq7fgUG+QTU/bDqj8tlgLXORIUIvPML6Knw/TMeCA3mxhiO+ejMJd9sOYnLPFMjXQH06j2oTMKyspVUH7r7fvEIRRDMPoMWxCbMmDmaP3eD/vGaptFO1RrNgZFoBf/tQQTdu3/wkVW7klM0UM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758611481; c=relaxed/simple; bh=waC9dgIqg8z/AIiVMHOz+qm2FlxkiISRWa2YwZxCvBM=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=uHgSMV9KDR6J67qCs1bpZAJRVEMRt3rol/giLDisJie+wPfVECFFWyi1I2ihhryA+cUNu48kS9PhdOxCWfc1dH2NG/ET60GHJwPNJIkGn2y5Dy7ijY/iqd1dq0m/uizKcNl0MAuxbZFtAoQpbAYKPBGZ2/eHpQl0enyW6iTokRo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.93.142]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4cWB3L3hclzKHMW3; Tue, 23 Sep 2025 15:11:10 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 568E01A0F60; Tue, 23 Sep 2025 15:11:15 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgD3CGEPSNJofU8hAg--.14578S4; Tue, 23 Sep 2025 15:11:13 +0800 (CST) From: Yu Kuai To: axboe@kernel.dk, martin.petersen@oracle.com, hare@suse.de, ming.lei@redhat.com Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai3@huawei.com, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com, johnny.chenyi@huawei.com Subject: [PATCH] blk-mq: fix null-ptr-deref in blk_mq_free_tags() from error path Date: Tue, 23 Sep 2025 15:01:01 +0800 Message-Id: <20250923070101.3507251-1-yukuai1@huaweicloud.com> X-Mailer: git-send-email 2.39.2 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 X-CM-TRANSID: gCh0CgD3CGEPSNJofU8hAg--.14578S4 X-Coremail-Antispam: 1UD129KBjvJXoW7AFy3Xr4UKrWrGrW5JF15XFb_yoW8uw4UpF W3Ga1UK343KrnrZFsrta9rA340kanYqF4xGas3uw15ZrnxCrWagF1vqr45Zr10vrZ8CFsI gF45tryrA3WDJ37anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9Y14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lFIxGxcIEc7CjxVA2 Y2ka0xkIwI1lc7CjxVAaw2AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x 0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2 zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF 4lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWU CwCI42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCT nIWIevJa73UjIFyTuYvjfUonmRUUUUU X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ Content-Type: text/plain; charset="utf-8" From: Yu Kuai blk_mq_free_tags() can be called after blk_mq_init_tags(), while tags->page_list is still not initialized, causing null-ptr-deref. Fix this problem by initializing tags->page_list at blk_mq_init_tags(), meanwhile, also free tags directly from error path because there is no srcu barrier. Fixes: ad0d05dbddc1 ("blk-mq: Defer freeing of tags page_list to SRCU callb= ack") Reported-by: syzbot+5c5d41e80248d610221f@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68d1b079.a70a0220.1b52b.0000.GAE@google= .com/ Signed-off-by: Yu Kuai Reviewed-by: Ming Lei --- block/blk-mq-tag.c | 9 +++++++++ block/blk-mq.c | 2 -- 2 files changed, 9 insertions(+), 2 deletions(-) diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c index a63d21a4aab4..23f7731f19d1 100644 --- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -569,6 +569,8 @@ struct blk_mq_tags *blk_mq_init_tags(unsigned int total= _tags, tags->nr_tags =3D total_tags; tags->nr_reserved_tags =3D reserved_tags; spin_lock_init(&tags->lock); + INIT_LIST_HEAD(&tags->page_list); + if (bt_alloc(&tags->bitmap_tags, depth, round_robin, node)) goto out_free_tags; if (bt_alloc(&tags->breserved_tags, reserved_tags, round_robin, node)) @@ -606,6 +608,13 @@ void blk_mq_free_tags(struct blk_mq_tag_set *set, stru= ct blk_mq_tags *tags) { sbitmap_queue_free(&tags->bitmap_tags); sbitmap_queue_free(&tags->breserved_tags); + + /* if tags pages is not allocated yet, free tags directly */ + if (list_empty(&tags->page_list)) { + kfree(tags); + return; + } + call_srcu(&set->tags_srcu, &tags->rcu_head, blk_mq_free_tags_callback); } =20 diff --git a/block/blk-mq.c b/block/blk-mq.c index 4ccf11cadf8c..09f579414161 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3582,8 +3582,6 @@ static int blk_mq_alloc_rqs(struct blk_mq_tag_set *se= t, if (node =3D=3D NUMA_NO_NODE) node =3D set->numa_node; =20 - INIT_LIST_HEAD(&tags->page_list); - /* * rq_size is the size of the request plus driver payload, rounded * to the cacheline size --=20 2.39.2