On 30.04.2018 11:04, Borislav Petkov wrote: > On Mon, Apr 23, 2018 at 11:34:07PM +0200, Maciej S. Szmigiero wrote: >> --- a/arch/x86/kernel/cpu/microcode/amd.c >> +++ b/arch/x86/kernel/cpu/microcode/amd.c >> +/* >> + * 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.
These checking functions are supposed to be called in order: first verify_container() verifies the basic container, then verify_equivalence_table() verifies the equivalence table while not repeating the checks that were already done by the former function. >> + 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. Same situation here. >> + >> +/* >> + * 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. > And a similar situation here - verify_patch() does not verify things that were already checked by verify_container() or verify_patch_section(). Thanks, Maciej