Commits
Martin Schwidefsky committed 8ab867cb080
s390/mm: fix BUG_ON in crst_table_upgrade
A 31-bit compat process can force a BUG_ON in crst_table_upgrade
with specific, invalid mmap calls, e.g.
mmap((void*) 0x7fff8000, 0x10000, 3, 32, -1, 0)
The arch_get_unmapped_area[_topdown] functions miss an if condition
in the decision to do a page table upgrade.
Fixes: 9b11c7912d00 ("s390/mm: simplify arch_get_unmapped_area[_topdown]")
Cc: <stable@vger.kernel.org> # v4.12+
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>