From 1cbc4d89c45cba3929f1c0cb4bca0b000c4f174b Mon Sep 17 00:00:00 2001 From: Andrew Cooper Date: Tue, 9 Feb 2021 22:10:54 +0000 Subject: [PATCH] x86/ucode/amd: Fix OoB read in cpu_request_microcode() verify_patch_size() is a maximum size check, and doesn't have a minimum bound. If the microcode container encodes a blob with a length less than 64 bytes, the subsequent calls to microcode_fits()/compare_header() may read off the end of the buffer. Fixes: 4de936a38a ("x86/ucode/amd: Rework parsing logic in cpu_request_microcode()") Signed-off-by: Andrew Cooper Reviewed-by: Jan Beulich --- xen/arch/x86/cpu/microcode/amd.c | 1 + 1 file changed, 1 insertion(+) diff --git a/xen/arch/x86/cpu/microcode/amd.c b/xen/arch/x86/cpu/microcode/amd.c index 5255028af7..3e51e53c1f 100644 --- a/xen/arch/x86/cpu/microcode/amd.c +++ b/xen/arch/x86/cpu/microcode/amd.c @@ -349,6 +349,7 @@ static struct microcode_patch *cpu_request_microcode(const void *buf, size_t siz if ( size < sizeof(*mc) || (mc = buf)->type != UCODE_UCODE_TYPE || size - sizeof(*mc) < mc->len || + mc->len < sizeof(struct microcode_patch) || (!skip_ucode && !verify_patch_size(mc->len)) ) { printk(XENLOG_ERR "microcode: Bad microcode data\n"); -- 2.39.5