Commit f4ff2591 authored by Maciej S. Szmigiero's avatar Maciej S. Szmigiero Committed by Borislav Petkov
Browse files

x86/microcode/AMD: Add microcode container verification 



Add container and patch verification functions to the AMD microcode
update driver.

These functions check whether a passed buffer contains the relevant
structure, whether it isn't truncated and (for actual microcode patches)
whether the size of a patch is not too large for a particular CPU family.
By adding these checks as separate functions the actual microcode loading
code won't get interspersed with a lot of checks and so will be more
readable.

 [ bp: Make all pr_err() calls into pr_debug() and drop the
   verify_patch() bits. ]

Signed-off-by: default avatarMaciej S. Szmigiero <mail@maciej.szmigiero.name>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Cc: x86-ml <x86@kernel.org>
Link: http://lkml.kernel.org/r/3014e96c82cd90761b4601bd2cfe59c4119e46a7.1529424596.git.mail@maciej.szmigiero.name
parent 479229d1

arch/x86/kernel/cpu/microcode/amd.c

+101 −0
Original line number Diff line number Diff line
@@ -73,6 +73,107 @@ static u16 find_equiv_id(struct equiv_cpu_entry *equiv_table, u32 sig) 
	return 0;

}



/*

 * Check whether there is a valid microcode container file at the beginning

 * of @buf of size @buf_size. Set @early to use this function in the early path.

 */

static bool verify_container(const u8 *buf, size_t buf_size, bool early)

{

	u32 cont_magic;



	if (buf_size <= CONTAINER_HDR_SZ) {

		if (!early)

			pr_debug("Truncated microcode container header.\n");



		return false;

	}



	cont_magic = *(const u32 *)buf;

	if (cont_magic != UCODE_MAGIC) {

		if (!early)

			pr_debug("Invalid magic value (0x%08x).\n", cont_magic);



		return false;

	}



	return true;

}



/*

 * Check whether there is a valid, non-truncated CPU equivalence table at the

 * beginning of @buf of size @buf_size. Set @early to use this function in the

 * early path.

 */

static bool verify_equivalence_table(const u8 *buf, size_t buf_size, bool early)

{

	const u32 *hdr = (const u32 *)buf;

	u32 cont_type, equiv_tbl_len;



	if (!verify_container(buf, buf_size, early))

		return false;



	cont_type = hdr[1];

	if (cont_type != UCODE_EQUIV_CPU_TABLE_TYPE) {

		if (!early)

			pr_debug("Wrong microcode container equivalence table type: %u.\n",

			       cont_type);



		return false;

	}



	buf_size -= CONTAINER_HDR_SZ;



	equiv_tbl_len = hdr[2];

	if (equiv_tbl_len < sizeof(struct equiv_cpu_entry) ||

	    buf_size < equiv_tbl_len) {

		if (!early)

			pr_debug("Truncated equivalence table.\n");



		return false;

	}



	return true;

}



/*

 * Check whether there is a valid, non-truncated microcode patch section at the

 * beginning of @buf of size @buf_size. Set @early to use this function in the

 * early path.

 */

static bool verify_patch_section(const u8 *buf, size_t buf_size, bool early)

{

	const u32 *hdr;

	u32 patch_type, patch_size;



	if (buf_size < SECTION_HDR_SIZE) {

		if (!early)

			pr_debug("Truncated patch section.\n");



		return false;

	}



	hdr = (const u32 *)buf;

	patch_type = hdr[0];

	patch_size = hdr[1];



	if (patch_type != UCODE_UCODE_TYPE) {

		if (!early)

			pr_debug("Invalid type field (0x%x) in container file section header.\n",

				patch_type);



		return false;

	}



	if (patch_size < sizeof(struct microcode_header_amd)) {

		if (!early)

			pr_debug("Patch of size %u too short.\n", patch_size);



		return false;

	}



	return true;

}



/*

 * This scans the ucode blob for the proper container as we can have multiple

 * containers glued together. Returns the equivalence ID from the equivalence

CRA Git | Maintained and supported by SUSTech CRA and CCSE