diff options
| author | Dan Williams <dan.j.williams@intel.com> | 2021-02-01 16:20:40 -0800 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2021-02-01 16:20:40 -0800 |
| commit | 7018c897c2f243d4b5f1b94bc6b4831a7eab80fb (patch) | |
| tree | 6383c6bcef1c705d22d3f753d4a3efc32d6150f9 | |
| parent | 50f558a5fe16b385cf1427b2a96149f4f68952d9 (diff) | |
libnvdimm/dimm: Avoid race between probe and available_slots_show()
Richard reports that the following test:
(while true; do
cat /sys/bus/nd/devices/nmem*/available_slots 2>&1 > /dev/null
done) &
while true; do
for i in $(seq 0 4); do
echo nmem$i > /sys/bus/nd/drivers/nvdimm/bind
done
for i in $(seq 0 4); do
echo nmem$i > /sys/bus/nd/drivers/nvdimm/unbind
done
done
...fails with a crash signature like:
divide error: 0000 [#1] SMP KASAN PTI
RIP: 0010:nd_label_nfree+0x134/0x1a0 [libnvdimm]
[..]
Call Trace:
available_slots_show+0x4e/0x120 [libnvdimm]
dev_attr_show+0x42/0x80
? memset+0x20/0x40
sysfs_kf_seq_show+0x218/0x410
The root cause is that available_slots_show() consults driver-data, but
fails to synchronize against device-unbind setting up a TOCTOU race to
access uninitialized memory.
Validate driver-data under the device-lock.
Fixes: 4d88a97aa9e8 ("libnvdimm, nvdimm: dimm driver and base libnvdimm device-driver infrastructure")
Cc: <stable@vger.kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Coly Li <colyli@suse.com>
Reported-by: Richard Palethorpe <rpalethorpe@suse.com>
Acked-by: Richard Palethorpe <rpalethorpe@suse.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
| -rw-r--r-- | drivers/nvdimm/dimm_devs.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c index b59032e0859b..9d208570d059 100644 --- a/drivers/nvdimm/dimm_devs.c +++ b/drivers/nvdimm/dimm_devs.c @@ -335,16 +335,16 @@ static ssize_t state_show(struct device *dev, struct device_attribute *attr, } static DEVICE_ATTR_RO(state); -static ssize_t available_slots_show(struct device *dev, - struct device_attribute *attr, char *buf) +static ssize_t __available_slots_show(struct nvdimm_drvdata *ndd, char *buf) { - struct nvdimm_drvdata *ndd = dev_get_drvdata(dev); + struct device *dev; ssize_t rc; u32 nfree; if (!ndd) return -ENXIO; + dev = ndd->dev; nvdimm_bus_lock(dev); nfree = nd_label_nfree(ndd); if (nfree - 1 > nfree) { @@ -356,6 +356,18 @@ static ssize_t available_slots_show(struct device *dev, nvdimm_bus_unlock(dev); return rc; } + +static ssize_t available_slots_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + ssize_t rc; + + nd_device_lock(dev); + rc = __available_slots_show(dev_get_drvdata(dev), buf); + nd_device_unlock(dev); + + return rc; +} static DEVICE_ATTR_RO(available_slots); __weak ssize_t security_show(struct device *dev, |