s390/mm: do not trigger write fault when vma does not allow VM_WRITE

For non-protection pXd_none() page faults in do_dat_exception(), we
call do_exception() with access == (VM_READ | VM_WRITE | VM_EXEC).
In do_exception(), vma->vm_flags is checked against that before
calling handle_mm_fault().

Since commit 92f842eac7ee3 ("[S390] store indication fault optimization"),
we call handle_mm_fault() with FAULT_FLAG_WRITE, when recognizing that
it was a write access. However, the vma flags check is still only
checking against (VM_READ | VM_WRITE | VM_EXEC), and therefore also
calling handle_mm_fault() with FAULT_FLAG_WRITE in cases where the vma
does not allow VM_WRITE.

Fix this by changing access check in do_exception() to VM_WRITE only,
when recognizing write access.

Link: https://lkml.kernel.org/r/[email protected]
Fixes: 92f842eac7ee3 ("[S390] store indication fault optimization")
Cc: <[email protected]>
Reported-by: David Hildenbrand <[email protected]>
Reviewed-by: Heiko Carstens <[email protected]>
Signed-off-by: Gerald Schaefer <[email protected]>
Signed-off-by: Vasily Gorbik <[email protected]>

0 files changed, 0 insertions, 0 deletions