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

Amadeusz reports KASAN use-after-free errors introduced by commit
8b001c3acea8 ("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.

Cc: <stable@vger.kernel.org> # v6.0
Link: https://lore.kernel.org/all/a101a10a-4fbb-5fae-2e3c-76cf96ed8fbd@linux.intel.com/
Fixes: 8b001c3acea8 ("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>

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 9624735f15757e8e38b3eff805c8f620c25871b0..3ecdc43a3f2bb3961199c6729434c99c5b030ce6 100644 (file)
--- 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);
                }