On Fri, Mar 16, 2018 at 12:07:50AM +0100, Maciej S. Szmigiero wrote:
> Before loading a CPU equivalence table from a microcode container file we
> need to verify whether this file is actually large enough to contain the
> table of a size indicated in this file.
> If it is not, there is no point of continuing with loading it since
> microcode patches are located after the equivalence table anyway.
>
> This patch adds these checks to the early loader.
>
> Signed-off-by: Maciej S. Szmigiero <m...@maciej.szmigiero.name>
> ---
> arch/x86/kernel/cpu/microcode/amd.c | 35 +++++++++++++++++++++++------------
> 1 file changed, 23 insertions(+), 12 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/microcode/amd.c
> b/arch/x86/kernel/cpu/microcode/amd.c
> index 6a93be0f771c..138c9fb983f2 100644
> --- a/arch/x86/kernel/cpu/microcode/amd.c
> +++ b/arch/x86/kernel/cpu/microcode/amd.c
> @@ -80,20 +80,33 @@ static u16 find_equiv_id(struct equiv_cpu_entry
> *equiv_table, u32 sig)
> * Returns the amount of bytes consumed while scanning. @desc contains all
> the
> * data we're going to use in later stages of the application.
> */
> -static ssize_t parse_container(u8 *ucode, ssize_t size, struct cont_desc
> *desc)
> +static size_t parse_container(u8 *ucode, size_t size, struct cont_desc *desc)
> {
> struct equiv_cpu_entry *eq;
> - ssize_t orig_size = size;
> + size_t orig_size = size;
> u32 *hdr = (u32 *)ucode;
> + unsigned int cont_magic, cont_type;
> + size_t equiv_tbl_len;
> u16 eq_id;
> u8 *buf;
>
> + if (size < CONTAINER_HDR_SZ)
> + return 0;
> +
> + cont_magic = hdr[0];
> + cont_type = hdr[1];
> + equiv_tbl_len = hdr[2];
All three are u32.
> /* Am I looking at an equivalence table header? */
> - if (hdr[0] != UCODE_MAGIC ||
> - hdr[1] != UCODE_EQUIV_CPU_TABLE_TYPE ||
> - hdr[2] == 0)
> + if (cont_magic != UCODE_MAGIC ||
> + cont_type != UCODE_EQUIV_CPU_TABLE_TYPE ||
> + equiv_tbl_len == 0)
> return CONTAINER_HDR_SZ;
>
> + if (equiv_tbl_len < sizeof(*eq) ||
If you do this, then the above == 0 check can go.
> + size - CONTAINER_HDR_SZ < equiv_tbl_len)
> + return size;
> +
> buf = ucode;
>
> eq = (struct equiv_cpu_entry *)(buf + CONTAINER_HDR_SZ);
--
Regards/Gruss,
Boris.
ECO tip #101: Trim your mails when you reply. Srsly.
