[PATCH] arm64: hibernate: check pgd table allocation

[Pavel Tatashin]

There is a bug in create_safe_exec_page(), when page table is allocated
it is not checked that table is allocated successfully:

But it is dereferenced in: pgd_none(READ_ONCE(*pgdp)).  Check that
allocation was successful.

Fixes: 82869ac57b5d ("arm64: kernel: Add support for hibernate/suspend-to-disk")

Signed-off-by: Pavel Tatashin <pasha.tatas...@soleen.com>
---
 arch/arm64/kernel/hibernate.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index e0a7fce0e01c..a96b2921d22c 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -201,6 +201,7 @@ static int create_safe_exec_page(void *src_start, size_t 
length,
                                 gfp_t mask)
 {
        int rc = 0;
+       pgd_t *trans_pgd;
        pgd_t *pgdp;
        pud_t *pudp;
        pmd_t *pmdp;
@@ -215,7 +216,13 @@ static int create_safe_exec_page(void *src_start, size_t 
length,
        memcpy((void *)dst, src_start, length);
        __flush_icache_range(dst, dst + length);
 
-       pgdp = pgd_offset_raw(allocator(mask), dst_addr);
+       trans_pgd = allocator(mask);
+       if (!trans_pgd) {
+               rc = -ENOMEM;
+               goto out;
+       }
+
+       pgdp = pgd_offset_raw(trans_pgd, dst_addr);
        if (pgd_none(READ_ONCE(*pgdp))) {
                pudp = allocator(mask);
                if (!pudp) {
-- 
2.23.0