diff options
| author | Peter Oberparleiter <oberpar@linux.ibm.com> | 2022-10-14 12:24:58 +0200 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2022-10-26 14:47:31 +0200 |
| commit | 1b6074112742f65ece71b0f299ca5a6a887d2db6 (patch) | |
| tree | 78483349496f75ed976e1e4cb3b4b313c0bcfaf5 | |
| parent | 8b1e6a3fb3feecdce8521154bfe30f9d1ebb70e6 (diff) | |
s390/cio: fix out-of-bounds access on cio_ignore free
The channel-subsystem-driver scans for newly available devices whenever
device-IDs are removed from the cio_ignore list using a command such as:
echo free >/proc/cio_ignore
Since an I/O device scan might interfer with running I/Os, commit
172da89ed0ea ("s390/cio: avoid excessive path-verification requests")
introduced an optimization to exclude online devices from the scan.
The newly added check for online devices incorrectly assumes that
an I/O-subchannel's drvdata points to a struct io_subchannel_private.
For devices that are bound to a non-default I/O subchannel driver, such
as the vfio_ccw driver, this results in an out-of-bounds read access
during each scan.
Fix this by changing the scan logic to rely on a driver-independent
online indication. For this we can use struct subchannel->config.ena,
which is the driver's requested subchannel-enabled state. Since I/Os
can only be started on enabled subchannels, this matches the intent
of the original optimization of not scanning devices where I/O might
be running.
Fixes: 172da89ed0ea ("s390/cio: avoid excessive path-verification requests")
Fixes: 0c3812c347bf ("s390/cio: derive cdev information only for IO-subchannels")
Cc: <stable@vger.kernel.org> # v5.15
Reported-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
| -rw-r--r-- | drivers/s390/cio/css.c | 8 |
1 files changed, 2 insertions, 6 deletions
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c index 913b6ddd040b..c7db95398500 100644 --- a/drivers/s390/cio/css.c +++ b/drivers/s390/cio/css.c @@ -753,13 +753,9 @@ static int __unset_online(struct device *dev, void *data) { struct idset *set = data; struct subchannel *sch = to_subchannel(dev); - struct ccw_device *cdev; - if (sch->st == SUBCHANNEL_TYPE_IO) { - cdev = sch_get_cdev(sch); - if (cdev && cdev->online) - idset_sch_del(set, sch->schid); - } + if (sch->st == SUBCHANNEL_TYPE_IO && sch->config.ena) + idset_sch_del(set, sch->schid); return 0; } |