[PATCH] efi: ssdt: Don't free memory if ACPI table was loaded successfully

[PATCH] efi: ssdt: Don't free memory if ACPI table was loaded successfully

[Ard Biesheuvel]

Amadeusz reports KASAN use-after-free errors introduced by commit
3881ee0b1edc ("efi: avoid efivars layer when loading SSDTs from
variables"). The problem appears to be that the memory that holds the
new ACPI table is now freed unconditionally, instead of only when the
ACPI core reported a failure to load the table.

So let's fix this, by omitting the kfree() on success.

Link: https://lore.kernel.org/all/a101a10a-4fbb-5fae-2e3c-76cf96ed8fbd@linux.intel.com/
Fixes: 3881ee0b1edc ("efi: avoid efivars layer when loading SSDTs from variables")
Reported-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 drivers/firmware/efi/efi.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 9624735f1575..3ecdc43a3f2b 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -271,6 +271,8 @@ static __init int efivar_ssdt_load(void)
 			acpi_status ret = acpi_load_table(data, NULL);
 			if (ret)
 				pr_err("failed to load table: %u\n", ret);
+			else
+				continue;
 		} else {
 			pr_err("failed to get var data: 0x%lx\n", status);
 		}
-- 
2.35.1