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linux/drivers/dax
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Adrian Huang d4c5da5049 dax: Fix stack overflow when mounting fsdax pmem device 
When mounting fsdax pmem device, commit 6180bb446a ("dax: fix
detection of dax support for non-persistent memory block devices")
introduces the stack overflow [1][2]. Here is the call path for
mounting ext4 file system:
  ext4_fill_super
    bdev_dax_supported
      __bdev_dax_supported
        dax_supported
          generic_fsdax_supported
            __generic_fsdax_supported
              bdev_dax_supported

The call path leads to the infinite calling loop, so we cannot
call bdev_dax_supported() in __generic_fsdax_supported(). The sanity
checking of the variable 'dax_dev' is moved prior to the two
bdev_dax_pgoff() checks [3][4].

[1] https://lore.kernel.org/linux-nvdimm/1420999447.1004543.1600055488770.JavaMail.zimbra@redhat.com/
[2] https://lore.kernel.org/linux-nvdimm/alpine.LRH.2.02.2009141131220.30651@file01.intranet.prod.int.rdu2.redhat.com/
[3] https://lore.kernel.org/linux-nvdimm/CA+RJvhxBHriCuJhm-D8NvJRe3h2MLM+ZMFgjeJjrRPerMRLvdg@mail.gmail.com/
[4] https://lore.kernel.org/linux-nvdimm/20200903160608.GU878166@iweiny-DESK2.sc.intel.com/

Fixes: 6180bb446a ("dax: fix detection of dax support for non-persistent memory block devices")
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Reported-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Adrian Huang <ahuang12@lenovo.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com>
Cc: Coly Li <colyli@suse.de>
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: John Pittman <jpittman@redhat.com>
Link: https://lore.kernel.org/r/20200917111549.6367-1-adrianhuang0701@gmail.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
 		2020-09-20 08:57:36 -07:00
..
pmem libnvdimm/namespace: Differentiate between probe mapping and runtime mapping 2019-11-14 19:08:47 -08:00
Kconfig device-dax: Add a driver for "hmem" devices 2019-11-07 15:45:00 +01:00
Makefile device-dax: Add a driver for "hmem" devices 2019-11-07 15:45:00 +01:00
bus.c dax: Move mandatory ->zero_page_range() check in alloc_dax() 2020-04-02 19:15:03 -07:00
bus.h dax: Fix alloc_dax_region() compile warning 2019-11-07 15:44:47 +01:00
dax-private.h device-dax: add memory via add_memory_driver_managed() 2020-06-04 19:06:23 -07:00
device.c memremap: rename MEMORY_DEVICE_DEVDAX to MEMORY_DEVICE_GENERIC 2020-09-04 09:59:59 +02:00
hmem.c device-dax: Add a driver for "hmem" devices 2019-11-07 15:45:00 +01:00
kmem.c device-dax: add memory via add_memory_driver_managed() 2020-06-04 19:06:23 -07:00
super.c dax: Fix stack overflow when mounting fsdax pmem device 2020-09-20 08:57:36 -07:00