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| author | Dan Williams <dan.j.williams@intel.com> | 2021-02-02 03:20:40 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-03-04 11:39:56 +0300 |
| commit | 77d97b563a71914fa34a7e272dea36a895ffe67e (patch) | |
| tree | 10b4351d2f93bf4bafda401949d20f8004729d1e /drivers/nvdimm | |
| parent | 669e2d7db25e7536e81b2db931f0e217746f76aa (diff) | |
| download | linux-77d97b563a71914fa34a7e272dea36a895ffe67e.tar.xz | |
libnvdimm/dimm: Avoid race between probe and available_slots_show()
commit 7018c897c2f243d4b5f1b94bc6b4831a7eab80fb upstream
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>
[sudip: use device_lock()]
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/nvdimm')
| -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 863cabc35215..f0e0e3b42c91 100644 --- a/drivers/nvdimm/dimm_devs.c +++ b/drivers/nvdimm/dimm_devs.c @@ -359,16 +359,16 @@ 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) { @@ -380,6 +380,18 @@ 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; + + device_lock(dev); + rc = __available_slots_show(dev_get_drvdata(dev), buf); + device_unlock(dev); + + return rc; +} static DEVICE_ATTR_RO(available_slots); static struct attribute *nvdimm_attributes[] = { |