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xen/66f2fd92-x86-ucode-Intel-stricter-sanity-check.patch

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# Commit 8752ad83e79754f8109457cff796e5f86f644348
# Date 2024-09-24 18:57:38 +0100
# Author Demi Marie Obenour <demi@invisiblethingslab.com>
# Committer Andrew Cooper <andrew.cooper3@citrix.com>
xen/ucode: Make Intel's microcode_sanity_check() stricter
The SDM states that data size must be a multiple of 4, but Xen doesn't check
this propery.
This is liable to cause a later failures, but should be checked explicitly.
Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/arch/x86/cpu/microcode/intel.c
+++ b/xen/arch/x86/cpu/microcode/intel.c
@@ -155,10 +155,13 @@ static int microcode_sanity_check(const
uint32_t sum;
/*
- * Total size must be a multiple of 1024 bytes. Data size and the header
- * must fit within it.
+ * The SDM states:
+ * - Data size must be a multiple of 4.
+ * - Total size must be a multiple of 1024 bytes. Data size and the
+ * header must fit within it.
*/
if ( (total_size & 1023) ||
+ (data_size & 3) ||
data_size > (total_size - MC_HEADER_SIZE) )
{
printk(XENLOG_WARNING "microcode: Bad size\n");