s390/mem_detect: fix detect_memory() error handling

[ Upstream commit 3400c35a4090704e6c465449616ab7e67a9209e7 ]

Currently if for some reason sclp_early_read_info() fails,
sclp_early_get_memsize() will not set max_physmem_end and it
will stay uninitialized. Any garbage value other than 0 will lead
to detect_memory() taking wrong path or returning a garbage value
as max_physmem_end. To avoid that simply initialize max_physmem_end.

Fixes: 73045a08cf55 ("s390: unify identity mapping limits handling")
Reported-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/s390/boot/mem_detect.c b/arch/s390/boot/mem_detect.c
index 2f949cd9076b81dbc4b1536d25229e49e7515a8f..17a32707d17e0c84984554d1c88674fb03ce674f 100644 (file)
--- a/arch/s390/boot/mem_detect.c
+++ b/arch/s390/boot/mem_detect.c
@@ -165,7 +165,7 @@ static void search_mem_end(void)
 
 unsigned long detect_memory(void)
 {
-       unsigned long max_physmem_end;
+       unsigned long max_physmem_end = 0;
 
        sclp_early_get_memsize(&max_physmem_end);