ata: libata-core: fix NULL pointer deref in ata_host_alloc_pinfo()

stable inclusion
from stable-4.19.249
commit a810bd5af06977a847d1f202b22d7defd5c62497
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5I4FP


CVE: NA

--------------------------------

[ Upstream commit bf476fe2 ]

In an unlikely (and probably wrong?) case that the 'ppi' parameter of
ata_host_alloc_pinfo() points to an array starting with a NULL pointer,
there's going to be a kernel oops as the 'pi' local variable won't get
reassigned from the initial value of NULL. Initialize 'pi' instead to
'&ata_dummy_port_info' to fix the possible kernel oops for good...

Found by Linux Verification Center (linuxtesting.org) with the SVACE static
analysis tool.

Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>