From nobody Sat May 9 09:26:40 2026 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (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 C23DE1DB13B; Fri, 24 Jan 2025 09:26:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737710816; cv=none; b=NhmF6hGEgYv2fUUM078/MNUp8RfpHjWzYtKpuyI/KS7jWDnD8zmYSZtdXhTqm7Kt8CGTn77GIjshrCR3Y5Ls5NDyX6EAb4gGb8u3u0EnHF3j5BAHKTcJQPPj0zmIBl7m8aNSzxPmMB2IWQkqDhsUOmrVCVfOtlegdb2M8abW10k= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737710816; c=relaxed/simple; bh=tqdLO+yQIQP8yBIlONpvJhABcwu34MdDJuOlgQmuzoQ=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=t48+RQQ2phrFn8Co9MbDaZXVTaRWqA+MCwIBFmarImTTx0DgWl/LQyqDtOp5K02CpnVbjLYzeH0zC/KKKKRc1mllJXJeAzAyg+mEuxRP8JJK+R6pY9JO/cpaVMPjBjcEgMzMiaO3NQ4YtO0HQ3yGWHyy97dgw1WybHhZ47ANMSQ= 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=45.249.212.51 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 [172.19.163.216]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4YfXW654hrz4f3kvM; Fri, 24 Jan 2025 17:26:26 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id A93F91A0E99; Fri, 24 Jan 2025 17:26:48 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgDXOl_UXJNnAphiBw--.10609S4; Fri, 24 Jan 2025 17:26:46 +0800 (CST) From: Yu Kuai To: song@kernel.org, yukuai3@huawei.com, harshit.m.mogalapalli@oracle.com, akpm@osdl.org, neilb@cse.unsw.edu.au Cc: linux-raid@vger.kernel.org, linux-kernel@vger.kernel.org, yukuai1@huaweicloud.com, yi.zhang@huawei.com, yangerkun@huawei.com Subject: [PATCH] md/md-bitmap: synchronize bitmap_get_stats() with bitmap lifetime Date: Fri, 24 Jan 2025 17:20:55 +0800 Message-Id: <20250124092055.4050195-1-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: gCh0CgDXOl_UXJNnAphiBw--.10609S4 X-Coremail-Antispam: 1UD129KBjvJXoWxur17ur43tFWUWr45Zry5Jwb_yoW5WrW5pa 93uFy5urW5Jr4rXrnrArykuFyFg3ZrtFZFgr93Cw1ruFy3Ar9xuF4fWFW7Xrn09ry8AFs0 qw45JF98WryUu3JanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9014x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26F4U JVW0owA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0 I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r 4UM4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628v n2kIc2xKxwCY1x0262kKe7AKxVWUtVW8ZwCF04k20xvY0x0EwIxGrwCFx2IqxVCFs4IE7x kEbVWUJVW8JwC20s026c02F40E14v26r1j6r18MI8I3I0E7480Y4vE14v26r106r1rMI8E 67AF67kF1VAFwI0_Jw0_GFylIxkGc2Ij64vIr41lIxAIcVC0I7IYx2IY67AKxVWUJVWUCw CI42IY6xIIjxv20xvEc7CjxVAFwI0_Jr0_Gr1lIxAIcVCF04k26cxKx2IYs7xG6r1j6r1x MIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAFwI0_Gr0_Gr1UYxBIda VFxhVjvjDU0xZFpf9x0JUd-B_UUUUU= X-CM-SenderInfo: 51xn3trlr6x35dzhxuhorxvhhfrp/ Content-Type: text/plain; charset="utf-8" From: Yu Kuai After commit ec6bb299c7c3 ("md/md-bitmap: add 'sync_size' into struct md_bitmap_stats"), following panic is reported: Oops: general protection fault, probably for non-canonical address RIP: 0010:bitmap_get_stats+0x2b/0xa0 Call Trace: md_seq_show+0x2d2/0x5b0 seq_read_iter+0x2b9/0x470 seq_read+0x12f/0x180 proc_reg_read+0x57/0xb0 vfs_read+0xf6/0x380 ksys_read+0x6c/0xf0 do_syscall_64+0x82/0x170 entry_SYSCALL_64_after_hwframe+0x76/0x7e Root cause is that bitmap_get_stats() can be called at anytime if mddev is still there, even if bitmap is destroyed, or not fully initialized. Deferenceing bitmap in this case can crash the kernel. Meanwhile, the above commit start to deferencing bitmap->storage, make the problem easier to trigger. Fix the problem by protecting bitmap_get_stats() by bitmap_info.mutex. Fixes: 32a7627cf3a3 ("[PATCH] md: optimised resync using Bitmap based inten= t logging") Reported-and-tested-by: Harshit Mogalapalli Closes: https://lore.kernel.org/linux-raid/ca3a91a2-50ae-4f68-b317-abd9889f= 3907@oracle.com/T/#m6e5086c95201135e4941fe38f9efa76daf9666c5 Signed-off-by: Yu Kuai --- drivers/md/md-bitmap.c | 5 ++++- drivers/md/md.c | 5 +++++ 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c index 63879582d1c3..e01c2d0479e3 100644 --- a/drivers/md/md-bitmap.c +++ b/drivers/md/md-bitmap.c @@ -2340,7 +2340,10 @@ static int bitmap_get_stats(void *data, struct md_bi= tmap_stats *stats) =20 if (!bitmap) return -ENOENT; - + if (bitmap->mddev->bitmap_info.external) + return -ENOENT; + if (!bitmap->storage.sb_page) /* no superblock */ + return -EINVAL; sb =3D kmap_local_page(bitmap->storage.sb_page); stats->sync_size =3D le64_to_cpu(sb->sync_size); kunmap_local(sb); diff --git a/drivers/md/md.c b/drivers/md/md.c index 94166b2e9512..c9de57701e43 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8470,6 +8470,10 @@ static int md_seq_show(struct seq_file *seq, void *v) return 0; =20 spin_unlock(&all_mddevs_lock); + + /* prevent bitmap to be freed after checking */ + mutex_lock(&mddev->bitmap_info.mutex); + spin_lock(&mddev->lock); if (mddev->pers || mddev->raid_disks || !list_empty(&mddev->disks)) { seq_printf(seq, "%s : ", mdname(mddev)); @@ -8545,6 +8549,7 @@ static int md_seq_show(struct seq_file *seq, void *v) seq_printf(seq, "\n"); } spin_unlock(&mddev->lock); + mutex_unlock(&mddev->bitmap_info.mutex); spin_lock(&all_mddevs_lock); =20 if (mddev =3D=3D list_last_entry(&all_mddevs, struct mddev, all_mddevs)) --=20 2.39.2