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Subject[PATCH v3 05/17] arm64, hibernate: check pgd table allocation
Date
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)).

Another issue, is that phys_to_ttbr() uses an offset in page table instead
of pgd directly.

So, allocate page table, check that allocation was successful, and use it
directly to set ttbr0_el1.

Signed-off-by: Pavel Tatashin <pasha.tatashin@soleen.com>
---
arch/arm64/kernel/hibernate.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c
index ee34a06d8a35..750ecc7f2cbe 100644
--- a/arch/arm64/kernel/hibernate.c
+++ b/arch/arm64/kernel/hibernate.c
@@ -199,6 +199,7 @@ static int create_safe_exec_page(void *src_start, size_t length,
phys_addr_t *phys_dst_addr)
{
void *page = (void *)get_safe_page(GFP_ATOMIC);
+ pgd_t *trans_pgd;
pgd_t *pgdp;
pud_t *pudp;
pmd_t *pmdp;
@@ -210,7 +211,11 @@ static int create_safe_exec_page(void *src_start, size_t length,
memcpy(page, src_start, length);
__flush_icache_range((unsigned long)page, (unsigned long)page + length);

- pgdp = pgd_offset_raw((void *)get_safe_page(GFP_ATOMIC), dst_addr);
+ trans_pgd = (void *)get_safe_page(GFP_ATOMIC);
+ if (!trans_pgd)
+ return -ENOMEM;
+
+ pgdp = pgd_offset_raw(trans_pgd, dst_addr);
if (pgd_none(READ_ONCE(*pgdp))) {
pudp = (void *)get_safe_page(GFP_ATOMIC);
if (!pudp)
@@ -251,7 +256,7 @@ static int create_safe_exec_page(void *src_start, size_t length,
*/
cpu_set_reserved_ttbr0();
local_flush_tlb_all();
- write_sysreg(phys_to_ttbr(virt_to_phys(pgdp)), ttbr0_el1);
+ write_sysreg(phys_to_ttbr(virt_to_phys(trans_pgd)), ttbr0_el1);
isb();

*phys_dst_addr = virt_to_phys(page);
--
2.23.0
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