From d9032189bbe791846b2c3e224ae164e106e2be1b Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 21 Sep 2022 20:10:10 -0700 Subject: [PATCH 22/36] 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 Signed-off-by: Kees Cook Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/lkml/CA+DvKQ+bp7Y7gmaVhacjv9uF6Ar-o4tet872h4Q8RPYPJjcJQA@mail.gmail.com/ (cherry picked from commit 712f210a457d9c32414df246a72781550bc23ef6) Signed-off-by: Mridula Shastry Reviewed-by: Todd Vierling --- arch/x86/include/asm/microcode.h | 1 + arch/x86/kernel/cpu/microcode/amd.c | 3 ++- 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/microcode.h b/arch/x86/include/asm/microcode.h index 67051a58a18b..629330986955 100644 --- a/arch/x86/include/asm/microcode.h +++ b/arch/x86/include/asm/microcode.h @@ -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; }; diff --git a/arch/x86/kernel/cpu/microcode/amd.c b/arch/x86/kernel/cpu/microcode/amd.c index 6ab27650f8a7..030f69f93c00 100644 --- a/arch/x86/kernel/cpu/microcode/amd.c +++ b/arch/x86/kernel/cpu/microcode/amd.c @@ -791,6 +791,7 @@ 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; @@ -868,7 +869,7 @@ static enum ucode_state load_microcode_amd(u8 family, const u8 *data, size_t siz } 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; } -- 2.39.3