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Date: Wed, 22 Feb 2012 10:01:53 +0900
From: "Jun'ichi Nomura" <j-nomura@...jp.nec.com>
To: Jens Axboe <axboe@...nel.dk>, Tejun Heo <tj@...nel.org>
CC: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
linux-scsi <linux-scsi@...r.kernel.org>,
Naveen Goswamy <naveen.goswamy@...ymtl.ca>,
James Bottomley <James.Bottomley@...senPartnership.com>,
Stefan Richter <stefanr@...6.in-berlin.de>,
Dave Jones <davej@...hat.com>, sgruszka@...hat.com,
Huajun Li <huajun.li.lee@...il.com>
Subject: [PATCH] Fix NULL pointer dereference in sd_revalidate_disk
Since 2.6.39 (1196f8b), when a driver returns -ENOMEDIUM for open(),
__blkdev_get() calls rescan_partitions() to remove
in-kernel partition structures and raise KOBJ_CHANGE uevent.
However it ends up calling driver's revalidate_disk without open
and could cause oops.
In the case of SCSI:
process A process B
----------------------------------------------
sys_open
__blkdev_get
sd_open
returns -ENOMEDIUM
scsi_remove_device
<scsi_device torn down>
rescan_partitions
sd_revalidate_disk
<oops>
Oopses are reported here:
http://marc.info/?l=linux-scsi&m=132388619710052
This patch separates the partition invalidation from rescan_partitions()
and use it for -ENOMEDIUM case.
Reported-by: Huajun Li <huajun.li.lee@...il.com>
Signed-off-by: Jun'ichi Nomura <j-nomura@...jp.nec.com>
--
block/partition-generic.c | 48 ++++++++++++++++++++++++++++++++++++++--------
fs/block_dev.c | 16 +++++++++++----
include/linux/genhd.h | 1
3 files changed, 53 insertions(+), 12 deletions(-)
diff --git a/include/linux/genhd.h b/include/linux/genhd.h
index fe23ee7..e61d319 100644
--- a/include/linux/genhd.h
+++ b/include/linux/genhd.h
@@ -596,6 +596,7 @@ extern char *disk_name (struct gendisk *hd, int partno, char *buf);
extern int disk_expand_part_tbl(struct gendisk *disk, int target);
extern int rescan_partitions(struct gendisk *disk, struct block_device *bdev);
+extern int invalidate_partitions(struct gendisk *disk, struct block_device *bdev);
extern struct hd_struct * __must_check add_partition(struct gendisk *disk,
int partno, sector_t start,
sector_t len, int flags,
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 0e575d1..5e9f198 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1183,8 +1183,12 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
* The latter is necessary to prevent ghost
* partitions on a removed medium.
*/
- if (bdev->bd_invalidated && (!ret || ret == -ENOMEDIUM))
- rescan_partitions(disk, bdev);
+ if (bdev->bd_invalidated) {
+ if (!ret)
+ rescan_partitions(disk, bdev);
+ else if (ret == -ENOMEDIUM)
+ invalidate_partitions(disk, bdev);
+ }
if (ret)
goto out_clear;
} else {
@@ -1214,8 +1218,12 @@ static int __blkdev_get(struct block_device *bdev, fmode_t mode, int for_part)
if (bdev->bd_disk->fops->open)
ret = bdev->bd_disk->fops->open(bdev, mode);
/* the same as first opener case, read comment there */
- if (bdev->bd_invalidated && (!ret || ret == -ENOMEDIUM))
- rescan_partitions(bdev->bd_disk, bdev);
+ if (bdev->bd_invalidated) {
+ if (!ret)
+ rescan_partitions(bdev->bd_disk, bdev);
+ else if (ret == -ENOMEDIUM)
+ invalidate_partitions(bdev->bd_disk, bdev);
+ }
if (ret)
goto out_unlock_bdev;
}
diff --git a/block/partition-generic.c b/block/partition-generic.c
index d06ec1c..6df5d69 100644
--- a/block/partition-generic.c
+++ b/block/partition-generic.c
@@ -389,17 +389,11 @@ static bool disk_unlock_native_capacity(struct gendisk *disk)
}
}
-int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
+static int drop_partitions(struct gendisk *disk, struct block_device *bdev)
{
- struct parsed_partitions *state = NULL;
struct disk_part_iter piter;
struct hd_struct *part;
- int p, highest, res;
-rescan:
- if (state && !IS_ERR(state)) {
- kfree(state);
- state = NULL;
- }
+ int res;
if (bdev->bd_part_count)
return -EBUSY;
@@ -412,6 +406,24 @@ rescan:
delete_partition(disk, part->partno);
disk_part_iter_exit(&piter);
+ return 0;
+}
+
+int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
+{
+ struct parsed_partitions *state = NULL;
+ struct hd_struct *part;
+ int p, highest, res;
+rescan:
+ if (state && !IS_ERR(state)) {
+ kfree(state);
+ state = NULL;
+ }
+
+ res = drop_partitions(disk, bdev);
+ if (res)
+ return res;
+
if (disk->fops->revalidate_disk)
disk->fops->revalidate_disk(disk);
check_disk_size_change(disk, bdev);
@@ -515,6 +527,26 @@ rescan:
return 0;
}
+int invalidate_partitions(struct gendisk *disk, struct block_device *bdev)
+{
+ int res;
+
+ if (!bdev->bd_invalidated)
+ return 0;
+
+ res = drop_partitions(disk, bdev);
+ if (res)
+ return res;
+
+ set_capacity(disk, 0);
+ check_disk_size_change(disk, bdev);
+ bdev->bd_invalidated = 0;
+ /* tell userspace that the media / partition table may have changed */
+ kobject_uevent(&disk_to_dev(disk)->kobj, KOBJ_CHANGE);
+
+ return 0;
+}
+
unsigned char *read_dev_sector(struct block_device *bdev, sector_t n, Sector *p)
{
struct address_space *mapping = bdev->bd_inode->i_mapping;
--
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