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 7ED8F63DA for ; Thu, 5 Jan 2023 12:57:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E9408C433D2; Thu, 5 Jan 2023 12:57:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672923462; bh=cLuz4LSEAty/85tyXXL4axokUbINPGSn0BUoBf9FH3s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SJ6yiTQ3MMPh8mX9oybGYw5TObqStqDUZFnpYduq/VNKU/3y6xeSbbO5xDOKnFAuV 0NT2Vz6OxZ6TuMeaUvx9ZPDhrrbjEDpkx+/h7IvSP++QvMvrz1I4DBeEQkXpaZVbT3 TKl6lpv7RXMkjRejyvbUKRaIfEgOLRzhbR15y5FQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Shiwei Cui , Christoph Hellwig , Jan Kara , Ming Lei Subject: [PATCH 4.9 003/251] block: unhash blkdev part inode when the part is deleted Date: Thu, 5 Jan 2023 13:52:20 +0100 Message-Id: <20230105125334.897742203@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230105125334.727282894@linuxfoundation.org> References: <20230105125334.727282894@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: Ming Lei v5.11 changes the blkdev lookup mechanism completely since commit 22ae8ce8b892 ("block: simplify bdev/disk lookup in blkdev_get"), and small part of the change is to unhash part bdev inode when deleting partition. Turns out this kind of change does fix one nasty issue in case of BLOCK_EXT_MAJOR: 1) when one partition is deleted & closed, disk_put_part() is always called before bdput(bdev), see blkdev_put(); so the part's devt can be freed & re-used before the inode is dropped 2) then new partition with same devt can be created just before the inode in 1) is dropped, then the old inode/bdev structurein 1) is re-used for this new partition, this way causes use-after-free and kernel panic. It isn't possible to backport the whole big patchset of "merge struct block_device and struct hd_struct v4" for addressing this issue. https://lore.kernel.org/linux-block/20201128161510.347752-1-hch@lst.de/ So fixes it by unhashing part bdev in delete_partition(), and this way is actually aligned with v5.11+'s behavior. Backported from the following 5.10.y commit: 5f2f77560591 ("block: unhash blkdev part inode when the part is deleted") Reported-by: Shiwei Cui Tested-by: Shiwei Cui Cc: Christoph Hellwig Cc: Jan Kara Signed-off-by: Ming Lei Signed-off-by: Greg Kroah-Hartman --- block/partition-generic.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/block/partition-generic.c +++ b/block/partition-generic.c @@ -254,6 +254,7 @@ void delete_partition(struct gendisk *di { struct disk_part_tbl *ptbl = disk->part_tbl; struct hd_struct *part; + struct block_device *bdev; if (partno >= ptbl->len) return; @@ -267,6 +268,11 @@ void delete_partition(struct gendisk *di kobject_put(part->holder_dir); device_del(part_to_dev(part)); + bdev = bdget(part_devt(part)); + if (bdev) { + remove_inode_hash(bdev->bd_inode); + bdput(bdev); + } hd_struct_kill(part); }