device-dax: fix private mapping restriction, permit read-only
Hugh notes in response to commit 4cb19355 "device-dax: fail all private mapping attempts": "I think that is more restrictive than you intended: haven't tried, but I believe it rejects a PROT_READ, MAP_SHARED, O_RDONLY fd mmap, leaving no way to mmap /dev/dax without write permission to it." Indeed it does restrict read-only mappings, switch to checking VM_MAYSHARE, not VM_SHARED. Cc: <stable@vger.kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Pawel Lebioda <pawel.lebioda@intel.com> Fixes: 4cb19355 ("device-dax: fail all private mapping attempts") Reported-by:Hugh Dickins <hughd@google.com> Signed-off-by:
Dan Williams <dan.j.williams@intel.com>
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