device-dax: check devm_nsio_enable() return value

commit 6a84fb4b4e439a8ef0ce19ec7e7661ad76f655c9 upstream.

If the dax_pmem driver is passed a resource that is already busy the
driver probe attempt should fail with a message like the following:

  dax_pmem dax0.1: could not reserve region [mem 0x100000000-0x11fffffff]

However, if we do not catch the error we crash for the obvious reason of
accessing memory that is not mapped.

 BUG: unable to handle kernel paging request at ffffc90020001000
 IP: [<ffffffff81496712>] __memcpy+0x12/0x20
 [..]
 Call Trace:
  [<ffffffff815c4960>] ? nsio_rw_bytes+0x60/0x180
  [<ffffffff815c6045>] nd_pfn_validate+0x75/0x320
  [<ffffffff815c63a9>] nvdimm_setup_pfn+0xb9/0x5d0
  [<ffffffff815c48ef>] ? devm_nsio_enable+0xff/0x110
  [<ffffffff815cb699>] dax_pmem_probe+0x59/0x260

Fixes: ab68f2622136 ("/dev/dax, pmem: direct access to persistent memory")
Reported-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/dax/pmem.c b/drivers/dax/pmem.c
index 73ae849f51706582e8b850102dd4fa7f2ac743ab..76dd42dd7088d54964f8e6c1a6f339d654ef37a1 100644 (file)
--- a/drivers/dax/pmem.c
+++ b/drivers/dax/pmem.c
@@ -77,7 +77,9 @@ static int dax_pmem_probe(struct device *dev)
        nsio = to_nd_namespace_io(&ndns->dev);
 
        /* parse the 'pfn' info block via ->rw_bytes */
-       devm_nsio_enable(dev, nsio);
+       rc = devm_nsio_enable(dev, nsio);
+       if (rc)
+               return rc;
        altmap = nvdimm_setup_pfn(nd_pfn, &res, &__altmap);
        if (IS_ERR(altmap))
                return PTR_ERR(altmap);