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device-dax: fail all private mapping attempts

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The device-dax implementation originally tried to be tricky and allow
private read-only mappings, but in the process allowed writable
MAP_PRIVATE + MAP_NORESERVE mappings.  For simplicity and predictability
just fail all private mapping attempts since device-dax memory is
statically allocated and will never support overcommit.

Cc: <stable@vger.kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Fixes: dee4107924 ("/dev/dax, core: file operations and dax-mmap")
Reported-by: Pawel Lebioda <pawel.lebioda@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2016-11-16 09:00:38 -08:00
parent 6a84fb4b4e
commit 4cb19355ea
1 changed files with 2 additions and 2 deletions
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4
drivers/dax/dax.c
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@ -270,8 +270,8 @@ static int check_vma(struct dax_dev *dax_dev, struct vm_area_struct *vma,
if (!dax_dev->alive) if (!dax_dev->alive)
return -ENXIO; return -ENXIO;
/* prevent private / writable mappings from being established */ /* prevent private mappings from being established */
if ((vma->vm_flags & (VM_NORESERVE|VM_SHARED|VM_WRITE)) == VM_WRITE) { if ((vma->vm_flags & VM_SHARED) != VM_SHARED) {
dev_info(dev, "%s: %s: fail, attempted private mapping\n", dev_info(dev, "%s: %s: fail, attempted private mapping\n",
current->comm, func); current->comm, func);
return -EINVAL; return -EINVAL;