KEYS: correct alignment of system_certificate_list content in assembly file

Apart from data-type specific alignment constraints, there are also
architecture-specific alignment requirements.
For example, on s390 symbols must be on even addresses implying a 2-byte
alignment.  If the system_certificate_list_end symbol is on an odd address
and if this address is loaded, the least-significant bit is ignored.  As a
result, the load_system_certificate_list() fails to load the certificates
because of a wrong certificate length calculation.

To be safe, align system_certificate_list on an 8-byte boundary.  Also improve
the length calculation of the system_certificate_list content.  Introduce a
system_certificate_list_size (8-byte aligned because of unsigned long) variable
that stores the length.  Let the linker calculate this size by introducing
a start and end label for the certificate content.

Signed-off-by: Hendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: David Howells <dhowells@redhat.com>

2 files changed, 14 insertions, 4 deletions

diff --git a/kernel/system_certificates.S b/kernel/system_certificates.S
index 4aef390671cb..3e9868d47535 100644
--- a/kernel/system_certificates.S
+++ b/kernel/system_certificates.S
@@ -3,8 +3,18 @@
 
         __INITRODATA
 
+        .align 8
         .globl VMLINUX_SYMBOL(system_certificate_list)
 VMLINUX_SYMBOL(system_certificate_list):
+__cert_list_start:
         .incbin "kernel/x509_certificate_list"
-        .globl VMLINUX_SYMBOL(system_certificate_list_end)
-VMLINUX_SYMBOL(system_certificate_list_end):
+__cert_list_end:
+
+        .align 8
+        .globl VMLINUX_SYMBOL(system_certificate_list_size)
+VMLINUX_SYMBOL(system_certificate_list_size):
+#ifdef CONFIG_64BIT
+        .quad __cert_list_end - __cert_list_start
+#else
+        .long __cert_list_end - __cert_list_start
+#endif
diff --git a/kernel/system_keyring.c b/kernel/system_keyring.c
index 564dd93430a2..52ebc70263f4 100644
--- a/kernel/system_keyring.c
+++ b/kernel/system_keyring.c
@@ -22,7 +22,7 @@ struct key *system_trusted_keyring;
 EXPORT_SYMBOL_GPL(system_trusted_keyring);
 
 extern __initconst const u8 system_certificate_list[];
-extern __initconst const u8 system_certificate_list_end[];
+extern __initconst const unsigned long system_certificate_list_size;
 
 /*
  * Load the compiled-in keys
@@ -60,8 +60,8 @@ static __init int load_system_certificate_list(void)
 
         pr_notice("Loading compiled-in X.509 certificates\n");
 
-        end = system_certificate_list_end;
         p = system_certificate_list;
+        end = p + system_certificate_list_size;
         while (p < end) {
                 /* Each cert begins with an ASN.1 SEQUENCE tag and must be more
                  * than 256 bytes in size.