diff options
| author | Vasilis Liaskovitis <vliaskovitis@suse.com> | 2018-10-15 15:25:08 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2018-10-25 11:17:39 -0600 |
| commit | f92898e7f32e3533bfd95be174044bc349d416ca (patch) | |
| tree | 82d1f273e4246f03896141852cb4bf54f514ca70 | |
| parent | 3acbd2de6bc3af215c6ed7732dfc097d1e238503 (diff) | |
| download | linux-f92898e7f32e3533bfd95be174044bc349d416ca.tar.bz2 | |
xen/blkfront: avoid NULL blkfront_info dereference on device removal
If a block device is hot-added when we are out of grants,
gnttab_grant_foreign_access fails with -ENOSPC (log message "28
granting access to ring page") in this code path:
talk_to_blkback ->
setup_blkring ->
xenbus_grant_ring ->
gnttab_grant_foreign_access
and the failing path in talk_to_blkback sets the driver_data to NULL:
destroy_blkring:
blkif_free(info, 0);
mutex_lock(&blkfront_mutex);
free_info(info);
mutex_unlock(&blkfront_mutex);
dev_set_drvdata(&dev->dev, NULL);
This results in a NULL pointer BUG when blkfront_remove and blkif_free
try to access the failing device's NULL struct blkfront_info.
Cc: stable@vger.kernel.org # 4.5 and later
Signed-off-by: Vasilis Liaskovitis <vliaskovitis@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | drivers/block/xen-blkfront.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c index 9eea83ae01c6..56452cabce5b 100644 --- a/drivers/block/xen-blkfront.c +++ b/drivers/block/xen-blkfront.c @@ -2493,6 +2493,9 @@ static int blkfront_remove(struct xenbus_device *xbdev) dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename); + if (!info) + return 0; + blkif_free(info, 0); mutex_lock(&info->mutex); |