libsa: smbios: Reject a 64-bit entry point with revision 0

According to the specification, such an entry point may have different
data in bytes at offsets 0x0c to 0x17 (included).  In such a case,
interpreting them as the Structure Table Maximum Size and Address fields
could have catastrophic consequences.

Reviewed by:    imp, markj
MFC after:      2 weeks
Sponsored by:   The FreeBSD Foundation
Differential Revision:  https://reviews.freebsd.org/D49286

This commit is contained in:

Olivier Certner

2025-03-07 14:32:24 +01:00

parent 7e61fc7640

commit 64fc51a9cf

1 changed files with 7 additions and 0 deletions

									
										stand/libsa/smbios.c
									
		+7
		
												View File
												
				@@ -193,6 +193,13 @@ smbios_sigsearch(const caddr_t addr, const uint32_t len)

				#ifdef SMBIOS_64BIT_EP

						/* v3.0, 64-bit Entry point */

						if (strncmp(cp, SMBIOS3_SIG, sizeof(SMBIOS3_SIG) - 1) == 0 &&

						    /*

						     * The specification only guarantees the presence of the

						     * Structure Table Maximum Size and Address Entry fields at

						     * offsets 0x0c and 0x10 if the Entry Point Revision is not

						     * 0.

						     */

						    SMBIOS_GET8(cp, 0x0a) != 0 &&

						    smbios_checksum(cp, SMBIOS_GET8(cp, 0x06)) == 0) {

							smbios.is_64bit_ep = 1;

							return (cp);