Commit 712f210a authored by Kees Cook's avatar Kees Cook Committed by Borislav Petkov
Browse files

x86/microcode/AMD: Track patch allocation size explicitly 



In preparation for reducing the use of ksize(), record the actual
allocation size for later memcpy(). This avoids copying extra
(uninitialized!) bytes into the patch buffer when the requested
allocation size isn't exactly the size of a kmalloc bucket.
Additionally, fix potential future issues where runtime bounds checking
will notice that the buffer was allocated to a smaller value than
returned by ksize().

Fixes: 757885e9 ("x86, microcode, amd: Early microcode patch loading support for AMD")
Suggested-by: default avatarDaniel Micay <danielmicay@gmail.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/lkml/CA+DvKQ+bp7Y7gmaVhacjv9uF6Ar-o4tet872h4Q8RPYPJjcJQA@mail.gmail.com/
parent 7fce8d6e

arch/x86/include/asm/microcode.h

+1 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
struct ucode_patch {

	struct list_head plist;

	void *data;		/* Intel uses only this one */

	unsigned int size;

	u32 patch_id;

	u16 equiv_cpu;

};

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

+2 −1
Original line number Diff line number Diff line
@@ -788,6 +788,7 @@ static int verify_and_add_patch(u8 family, u8 *fw, unsigned int leftover, 
		kfree(patch);

		return -EINVAL;

	}

	patch->size = *patch_size;



	mc_hdr      = (struct microcode_header_amd *)(fw + SECTION_HDR_SIZE);

	proc_id     = mc_hdr->processor_rev_id;
@@ -869,7 +870,7 @@ load_microcode_amd(bool save, u8 family, const u8 *data, size_t size) 
		return ret;



	memset(amd_ucode_patch, 0, PATCH_MAX_SIZE);

	memcpy(amd_ucode_patch, p->data, min_t(u32, ksize(p->data), PATCH_MAX_SIZE));

	memcpy(amd_ucode_patch, p->data, min_t(u32, p->size, PATCH_MAX_SIZE));



	return ret;

}