arm64: hibernate: check pgd table allocation

[ Upstream commit 8c551f919a73c1dfa690a70a691be1da394145e8 ]

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")
Reviewed-by: James Morse <james.morse@arm.com>
Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index 9859e11..dbeeeff 100644 (file)
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -202,6 +202,7 @@ 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;
@@ -216,7 +217,13 @@ 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) {