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authorDan Williams <dan.j.williams@intel.com>2021-02-01 16:20:40 -0800
committerDan Williams <dan.j.williams@intel.com>2021-02-01 16:20:40 -0800
commit7018c897c2f243d4b5f1b94bc6b4831a7eab80fb (patch)
tree6383c6bcef1c705d22d3f753d4a3efc32d6150f9
parent50f558a5fe16b385cf1427b2a96149f4f68952d9 (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.c18
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,