Re: [PATCH] riscv: read-only pages should not be writable

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On 5/28/22 11:13, Ard Biesheuvel wrote:
On Sat, 28 May 2022 at 03:41, Heinrich Schuchardt
<heinrich.schuchardt@xxxxxxxxxxxxx> wrote:

If EFI pages are marked as read-only,
we should remove the _PAGE_WRITE flag.

The current code overwrites an unused value.

Fixes: b91540d52a08b ("RISC-V: Add EFI runtime services")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@xxxxxxxxxxxxx>
---
  arch/riscv/kernel/efi.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/efi.c b/arch/riscv/kernel/efi.c
index 024159298231..1aa540350abd 100644
--- a/arch/riscv/kernel/efi.c
+++ b/arch/riscv/kernel/efi.c
@@ -65,7 +65,7 @@ static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data)

         if (md->attribute & EFI_MEMORY_RO) {
                 val = pte_val(pte) & ~_PAGE_WRITE;
-               val = pte_val(pte) | _PAGE_READ;
+               val |= _PAGE_READ;
                 pte = __pte(val);
         }
         if (md->attribute & EFI_MEMORY_XP) {
--
2.36.1


Thanks Heinrich

Queued in efi/urgent.

I guess this should also be down-ported to 5.15 and 5.10.

Best regards

Heinrich



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