x86/microcode/AMD: Track patch allocation size explicitly
authorKees Cook <keescook@chromium.org>
Thu, 22 Sep 2022 03:10:10 +0000 (20:10 -0700)
committerBorislav Petkov <bp@suse.de>
Fri, 23 Sep 2022 11:46:26 +0000 (13:46 +0200)
commit712f210a457d9c32414df246a72781550bc23ef6
tree86b2cc803573d0b26bff74b8aeb41ba2e76bee37
parent7fce8d6eccbc31a561d07c79f359ad09f0424347
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: 757885e94a22 ("x86, microcode, amd: Early microcode patch loading support for AMD")
Suggested-by: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/lkml/CA+DvKQ+bp7Y7gmaVhacjv9uF6Ar-o4tet872h4Q8RPYPJjcJQA@mail.gmail.com/
arch/x86/include/asm/microcode.h
arch/x86/kernel/cpu/microcode/amd.c