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Date: Mon, 23 Nov 2020 13:23:18 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Chen Yu <yu.c.chen@...el.com>,
Borislav Petkov <bp@...e.de>
Subject: [PATCH 5.9 248/252] x86/microcode/intel: Check patch signature before saving microcode for early loading
From: Chen Yu <yu.c.chen@...el.com>
commit 1a371e67dc77125736cc56d3a0893f06b75855b6 upstream.
Currently, scan_microcode() leverages microcode_matches() to check
if the microcode matches the CPU by comparing the family and model.
However, the processor stepping and flags of the microcode signature
should also be considered when saving a microcode patch for early
update.
Use find_matching_signature() in scan_microcode() and get rid of the
now-unused microcode_matches() which is a good cleanup in itself.
Complete the verification of the patch being saved for early loading in
save_microcode_patch() directly. This needs to be done there too because
save_mc_for_early() will call save_microcode_patch() too.
The second reason why this needs to be done is because the loader still
tries to support, at least hypothetically, mixed-steppings systems and
thus adds all patches to the cache that belong to the same CPU model
albeit with different steppings.
For example:
microcode: CPU: sig=0x906ec, pf=0x2, rev=0xd6
microcode: mc_saved[0]: sig=0x906e9, pf=0x2a, rev=0xd6, total size=0x19400, date = 2020-04-23
microcode: mc_saved[1]: sig=0x906ea, pf=0x22, rev=0xd6, total size=0x19000, date = 2020-04-27
microcode: mc_saved[2]: sig=0x906eb, pf=0x2, rev=0xd6, total size=0x19400, date = 2020-04-23
microcode: mc_saved[3]: sig=0x906ec, pf=0x22, rev=0xd6, total size=0x19000, date = 2020-04-27
microcode: mc_saved[4]: sig=0x906ed, pf=0x22, rev=0xd6, total size=0x19400, date = 2020-04-23
The patch which is being saved for early loading, however, can only be
the one which fits the CPU this runs on so do the signature verification
before saving.
[ bp: Do signature verification in save_microcode_patch()
and rewrite commit message. ]
Fixes: ec400ddeff20 ("x86/microcode_intel_early.c: Early update ucode on Intel's CPU")
Signed-off-by: Chen Yu <yu.c.chen@...el.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: stable@...r.kernel.org
Link: https://bugzilla.kernel.org/show_bug.cgi?id=208535
Link: https://lkml.kernel.org/r/20201113015923.13960-1-yu.c.chen@intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/x86/kernel/cpu/microcode/intel.c | 63 +++++-----------------------------
1 file changed, 10 insertions(+), 53 deletions(-)
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -100,53 +100,6 @@ static int has_newer_microcode(void *mc,
return find_matching_signature(mc, csig, cpf);
}
-/*
- * Given CPU signature and a microcode patch, this function finds if the
- * microcode patch has matching family and model with the CPU.
- *
- * %true - if there's a match
- * %false - otherwise
- */
-static bool microcode_matches(struct microcode_header_intel *mc_header,
- unsigned long sig)
-{
- unsigned long total_size = get_totalsize(mc_header);
- unsigned long data_size = get_datasize(mc_header);
- struct extended_sigtable *ext_header;
- unsigned int fam_ucode, model_ucode;
- struct extended_signature *ext_sig;
- unsigned int fam, model;
- int ext_sigcount, i;
-
- fam = x86_family(sig);
- model = x86_model(sig);
-
- fam_ucode = x86_family(mc_header->sig);
- model_ucode = x86_model(mc_header->sig);
-
- if (fam == fam_ucode && model == model_ucode)
- return true;
-
- /* Look for ext. headers: */
- if (total_size <= data_size + MC_HEADER_SIZE)
- return false;
-
- ext_header = (void *) mc_header + data_size + MC_HEADER_SIZE;
- ext_sig = (void *)ext_header + EXT_HEADER_SIZE;
- ext_sigcount = ext_header->count;
-
- for (i = 0; i < ext_sigcount; i++) {
- fam_ucode = x86_family(ext_sig->sig);
- model_ucode = x86_model(ext_sig->sig);
-
- if (fam == fam_ucode && model == model_ucode)
- return true;
-
- ext_sig++;
- }
- return false;
-}
-
static struct ucode_patch *memdup_patch(void *data, unsigned int size)
{
struct ucode_patch *p;
@@ -164,7 +117,7 @@ static struct ucode_patch *memdup_patch(
return p;
}
-static void save_microcode_patch(void *data, unsigned int size)
+static void save_microcode_patch(struct ucode_cpu_info *uci, void *data, unsigned int size)
{
struct microcode_header_intel *mc_hdr, *mc_saved_hdr;
struct ucode_patch *iter, *tmp, *p = NULL;
@@ -210,6 +163,9 @@ static void save_microcode_patch(void *d
if (!p)
return;
+ if (!find_matching_signature(p->data, uci->cpu_sig.sig, uci->cpu_sig.pf))
+ return;
+
/*
* Save for early loading. On 32-bit, that needs to be a physical
* address as the APs are running from physical addresses, before
@@ -344,13 +300,14 @@ scan_microcode(void *data, size_t size,
size -= mc_size;
- if (!microcode_matches(mc_header, uci->cpu_sig.sig)) {
+ if (!find_matching_signature(data, uci->cpu_sig.sig,
+ uci->cpu_sig.pf)) {
data += mc_size;
continue;
}
if (save) {
- save_microcode_patch(data, mc_size);
+ save_microcode_patch(uci, data, mc_size);
goto next;
}
@@ -483,14 +440,14 @@ static void show_saved_mc(void)
* Save this microcode patch. It will be loaded early when a CPU is
* hot-added or resumes.
*/
-static void save_mc_for_early(u8 *mc, unsigned int size)
+static void save_mc_for_early(struct ucode_cpu_info *uci, u8 *mc, unsigned int size)
{
/* Synchronization during CPU hotplug. */
static DEFINE_MUTEX(x86_cpu_microcode_mutex);
mutex_lock(&x86_cpu_microcode_mutex);
- save_microcode_patch(mc, size);
+ save_microcode_patch(uci, mc, size);
show_saved_mc();
mutex_unlock(&x86_cpu_microcode_mutex);
@@ -935,7 +892,7 @@ static enum ucode_state generic_load_mic
* permanent memory. So it will be loaded early when a CPU is hot added
* or resumes.
*/
- save_mc_for_early(new_mc, new_mc_size);
+ save_mc_for_early(uci, new_mc, new_mc_size);
pr_debug("CPU%d found a matching microcode update with version 0x%x (current=0x%x)\n",
cpu, new_rev, uci->cpu_sig.rev);
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