On Mon, Apr 23, 2018 at 11:34:07PM +0200, Maciej S. Szmigiero wrote: > This commit adds verify_container(), verify_equivalence_table(),
Avoid beginning the commit message of a patch with "This patch" or "This commit". It is tautologically useless. > verify_patch_section() and verify_patch() functions to the AMD microcode > update driver. > These functions check whether a passed buffer contains the relevant > structure, whether it isn't truncated and (for actual microcode patches) > whether the size of a patch is not too large for a particular CPU family. > By adding these checks as separate functions the actual microcode loading > code won't get interspersed with a lot of checks and so will be more > readable. > > Signed-off-by: Maciej S. Szmigiero <[email protected]> > --- > arch/x86/kernel/cpu/microcode/amd.c | 140 > +++++++++++++++++++++++++++++++++++- > 1 file changed, 137 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kernel/cpu/microcode/amd.c > b/arch/x86/kernel/cpu/microcode/amd.c > index dc8ea9a9d962..4fafaf0852d7 100644 > --- a/arch/x86/kernel/cpu/microcode/amd.c > +++ b/arch/x86/kernel/cpu/microcode/amd.c > @@ -73,6 +73,142 @@ static u16 find_equiv_id(struct equiv_cpu_entry > *equiv_table, u32 sig) > return 0; > } > > +/* > + * Checks whether there is a valid microcode container file at the beginning > + * of a passed buffer @buf of size @size. > + * If @early is set this function does not print errors which makes it > + * usable by the early microcode loader. > + */ > +static bool verify_container(const u8 *buf, size_t buf_size, bool early) > +{ > + u32 cont_magic; > + > + if (buf_size <= CONTAINER_HDR_SZ) { > + if (!early) > + pr_err("Truncated microcode container header.\n"); > + > + return false; > + } > + > + cont_magic = *(const u32 *)buf; > + if (cont_magic != UCODE_MAGIC) { > + if (!early) > + pr_err("Invalid magic value (0x%08x).\n", cont_magic); > + > + return false; > + } > + > + return true; > +} > + > +/* > + * Checks whether there is a valid, non-truncated CPU equivalence table > + * at the beginning of a passed buffer @buf of size @size. > + * If @early is set this function does not print errors which makes it > + * usable by the early microcode loader. > + */ > +static bool verify_equivalence_table(const u8 *buf, size_t buf_size, bool > early) > +{ > + const u32 *hdr = (const u32 *)buf; > + u32 cont_type, equiv_tbl_len; > + > + cont_type = hdr[1]; You need to check the size of buf so that there's enough buf passed in before you index into it like that. > + if (cont_type != UCODE_EQUIV_CPU_TABLE_TYPE) { > + if (!early) > + pr_err("Wrong microcode container equivalence table > type: %u.\n", > + cont_type); > + > + return false; > + } > + > + equiv_tbl_len = hdr[2]; And that. > + if (equiv_tbl_len < sizeof(struct equiv_cpu_entry) || > + buf_size - CONTAINER_HDR_SZ < equiv_tbl_len) { > + if (!early) > + pr_err("Truncated equivalence table.\n"); > + > + return false; > + } > + > + return true; > +} > + > +/* > + * Checks whether there is a valid, non-truncated microcode patch section > + * at the beginning of a passed buffer @buf of size @size. > + * If @early is set this function does not print errors which makes it > + * usable by the early microcode loader. > + */ > +static bool verify_patch_section(const u8 *buf, size_t buf_size, bool early) > +{ > + const u32 *hdr = (const u32 *)buf; > + u32 patch_type, patch_size; > + > + if (buf_size < SECTION_HDR_SIZE) { > + if (!early) > + pr_err("Truncated patch section.\n"); > + > + return false; > + } > + > + patch_type = hdr[0]; > + patch_size = hdr[1]; > + > + if (patch_type != UCODE_UCODE_TYPE) { > + if (!early) > + pr_err("Invalid type field (%u) in container file > section header.\n", > + patch_type); > + > + return false; > + } > + > + if (patch_size < sizeof(struct microcode_header_amd)) { > + if (!early) > + pr_err("Patch of size %u too short.\n", patch_size); > + > + return false; > + } > + > + if (buf_size - SECTION_HDR_SIZE < patch_size) { > + if (!early) > + pr_err("Patch of size %u truncated.\n", patch_size); > + > + return false; > + } > + > + return true; > +} > + > +static unsigned int verify_patch_size(u8 family, u32 patch_size, > + unsigned int size); No forward declarations pls. > + > +/* > + * Checks whether a microcode patch located at the beginning of a passed > + * buffer @buf of size @size is not too large for a particular @family > + * and is not truncated. > + * If @early is set this function does not print errors which makes it > + * usable by the early microcode loader. > + */ > +static bool verify_patch(u8 family, const u8 *buf, size_t buf_size, bool > early) > +{ > + const u32 *hdr = (const u32 *)buf; > + u32 patch_size = hdr[1]; Just like in the first comment above. > + > + /* > + * The section header length is not included in this indicated size > + * but is present in the leftover file length so we need to subtract > + * it before passing this value to the function below. > + */ > + if (!verify_patch_size(family, patch_size, buf_size - > SECTION_HDR_SIZE)) { > + if (!early) > + pr_err("Patch of size %u too large.\n", patch_size); > + > + return false; > + } > + > + return true; > +} -- Regards/Gruss, Boris. Good mailing practices for 400: avoid top-posting and trim the reply.
