4.8-stable review patch. If anyone has any objections, please let me know.
------------------ From: Dan Williams <dan.j.willi...@intel.com> commit 4cb19355ea19995941ccaad115dbfac6b75215ca upstream. 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: Dave Hansen <dave.han...@linux.intel.com> Fixes: dee410792419 ("/dev/dax, core: file operations and dax-mmap") Reported-by: Pawel Lebioda <pawel.lebi...@intel.com> Signed-off-by: Dan Williams <dan.j.willi...@intel.com> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- drivers/dax/dax.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/dax/dax.c +++ b/drivers/dax/dax.c @@ -323,8 +323,8 @@ static int check_vma(struct dax_dev *dax if (!dax_dev->alive) return -ENXIO; - /* prevent private / writable mappings from being established */ - if ((vma->vm_flags & (VM_NORESERVE|VM_SHARED|VM_WRITE)) == VM_WRITE) { + /* prevent private mappings from being established */ + if ((vma->vm_flags & VM_SHARED) != VM_SHARED) { dev_info(dev, "%s: %s: fail, attempted private mapping\n", current->comm, func); return -EINVAL;