From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 10E2C257C for ; Thu, 23 Feb 2023 13:07:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 898A2C4339C; Thu, 23 Feb 2023 13:07:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1677157667; bh=+vzHs0CQPVIfw082TyBxGEZC1LLGnSLAg759kIH/oAU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=2YHnuoOuRQgLPoCqVmY2eMsurSU/QAxcK6ObU33MDeuPAoM67D5f//OwKEwDWfOGh RpYkTh24ySUYl0lf7JTCdc0u5uytj1665w24QeBZbMCX+rkp5cCdI2FRen7Z6QsBjO BIsPY+DZ50vN7DazCVkR2HQ573epV5I3JzI/O92g= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yu Kuai , Josef Bacik , Jens Axboe , Wen Yang Subject: [PATCH 5.10 19/25] nbd: fix max value for first_minor Date: Thu, 23 Feb 2023 14:06:36 +0100 Message-Id: <20230223130427.650259573@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230223130426.817998725@linuxfoundation.org> References: <20230223130426.817998725@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Yu Kuai commit e4c4871a73944353ea23e319de27ef73ce546623 upstream. commit b1a811633f73 ("block: nbd: add sanity check for first_minor") checks that 'first_minor' should not be greater than 0xff, which is wrong. Whitout the commit, the details that when user pass 0x100000, it ends up create sysfs dir "/sys/block/43:0" are as follows: nbd_dev_add disk->first_minor = index << part_shift -> default part_shift is 5, first_minor is 0x2000000 device_add_disk ddev->devt = MKDEV(disk->major, disk->first_minor) -> (0x2b << 20) | (0x2000000) = 0x2b00000 device_add device_create_sys_dev_entry format_dev_t sprintf(buffer, "%u:%u", MAJOR(dev), MINOR(dev)); -> got 43:0 sysfs_create_link -> /sys/block/43:0 By the way, with the wrong fix, when part_shift is the default value, only 8 ndb devices can be created since 8 << 5 is greater than 0xff. Since the max bits for 'first_minor' should be the same as what MKDEV() does, which is 20. Change the upper bound of 'first_minor' from 0xff to 0xfffff. Fixes: b1a811633f73 ("block: nbd: add sanity check for first_minor") Signed-off-by: Yu Kuai Reviewed-by: Josef Bacik Link: https://lore.kernel.org/r/20211102015237.2309763-2-yebin10@huawei.com Signed-off-by: Jens Axboe Signed-off-by: Wen Yang Signed-off-by: Greg Kroah-Hartman --- drivers/block/nbd.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -1773,11 +1773,11 @@ static int nbd_dev_add(int index) disk->major = NBD_MAJOR; /* Too big first_minor can cause duplicate creation of - * sysfs files/links, since first_minor will be truncated to - * byte in __device_add_disk(). + * sysfs files/links, since MKDEV() expect that the max bits of + * first_minor is 20. */ disk->first_minor = index << part_shift; - if (disk->first_minor > 0xff) { + if (disk->first_minor > MINORMASK) { err = -EINVAL; goto out_free_idr; }