git: c905b341204e - releng/14.4 - ucode: Fix validation on Intel platforms

The branch releng/14.4 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=c905b341204e92ce18c84b9ac33b643222c36d65

commit c905b341204e92ce18c84b9ac33b643222c36d65
Author:     Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2026-05-27 20:18:05 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2026-08-19 19:00:58 +0000

    ucode: Fix validation on Intel platforms
    
    The check for the extended signature table was backwards, so we always
    ignored it.
    
    We should verify that the extended signature table fits within the total
    image size.
    
    Approved by:    so
    Security:       FreeBSD-EN-26:20.microcode
    Reviewed by:    jrm, kib
    MFC after:      1 week
    Differential Revision:  https://reviews.freebsd.org/D57209
    
    (cherry picked from commit 0beb172898499fff51eed4df3d9284cd1094afbb)
    (cherry picked from commit 38cbd2588f0b6f677f42287af425ac913da46294)
---
 sys/x86/x86/ucode.c | 32 ++++++++++++++++++++++++--------
 1 file changed, 24 insertions(+), 8 deletions(-)

diff --git a/sys/x86/x86/ucode.c b/sys/x86/x86/ucode.c
index 298ce5448853..9233e9fa93a8 100644
--- a/sys/x86/x86/ucode.c
+++ b/sys/x86/x86/ucode.c
@@ -179,7 +179,6 @@ ucode_intel_match(const uint8_t *data, size_t *len)
 	uint64_t platformid;
 	size_t resid;
 	uint32_t data_size, flags, regs[4], sig, total_size;
-	int i;
 
 	do_cpuid(1, regs);
 	sig = regs[0];
@@ -201,19 +200,35 @@ ucode_intel_match(const uint8_t *data, size_t *len)
 		if (total_size == 0)
 			total_size = UCODE_INTEL_DEFAULT_DATA_SIZE +
 			    sizeof(struct ucode_intel_header);
-		if (data_size > total_size + sizeof(struct ucode_intel_header))
+
+		if (total_size > data_size + sizeof(struct ucode_intel_header))
 			table = (const struct ucode_intel_extsig_table *)
 			    ((const uint8_t *)(hdr + 1) + data_size);
 		else
 			table = NULL;
 
-		if (hdr->processor_signature == sig) {
-			if ((hdr->processor_flags & flags) != 0) {
-				*len = data_size;
-				return (hdr + 1);
+		if (hdr->processor_signature == sig &&
+		    (hdr->processor_flags & flags) != 0) {
+			*len = data_size;
+			return (hdr + 1);
+		}
+		if (table != NULL) {
+			size_t extsize;
+
+			extsize = total_size -
+			    (data_size + sizeof(struct ucode_intel_header));
+			if (extsize < sizeof(struct ucode_intel_extsig_table)) {
+				ucode_error = VERIFICATION_FAILED;
+				break;
 			}
-		} else if (table != NULL) {
-			for (i = 0; i < table->signature_count; i++) {
+			extsize -= sizeof(struct ucode_intel_extsig_table);
+			for (uint32_t i = 0; i < table->signature_count; i++) {
+				if (extsize < sizeof(struct ucode_intel_extsig)) {
+					ucode_error = VERIFICATION_FAILED;
+					goto out;
+				}
+				extsize -= sizeof(struct ucode_intel_extsig);
+
 				entry = &table->entries[i];
 				if (entry->processor_signature == sig &&
 				    (entry->processor_flags & flags) != 0) {
@@ -223,6 +238,7 @@ ucode_intel_match(const uint8_t *data, size_t *len)
 			}
 		}
 	}
+out:
 	return (NULL);
 }