Messages in this thread | | | Date | Fri, 11 Oct 2019 14:48:34 +0000 | From | Luis Chamberlain <> | Subject | Re: [PATCH v7 2/8] efi: Add embedded peripheral firmware support |
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On Fri, Oct 04, 2019 at 04:50:50PM +0200, Hans de Goede wrote: > +static int __init efi_check_md_for_embedded_firmware( > + efi_memory_desc_t *md, const struct efi_embedded_fw_desc *desc) > +{ > + const u64 prefix = *((u64 *)desc->prefix); > + struct sha256_state sctx; > + struct embedded_fw *fw; > + u8 sha256[32]; > + u64 i, size; > + void *map; > + > + size = md->num_pages << EFI_PAGE_SHIFT; > + map = memremap(md->phys_addr, size, MEMREMAP_WB);
Since our limitaiton is the init process must have mostly finished, it implies early x86 boot code cannot use this, what measures can we take to prevent / check for such conditions to be detected and gracefully errored out?
> + if (!map) { > + pr_err("Error mapping EFI mem at %#llx\n", md->phys_addr); > + return -ENOMEM; > + } > + > + size -= desc->length;
Remind me again, why we decrement the size here? I was going to ask if we didn't need a:
if (desc->length > size) { memunmap(map); return -EINVAL; }
> + for (i = 0; i < size; i += 8) { > + u64 *mem = map + i; > + > + if (*mem != prefix) > + continue; > + > + sha256_init(&sctx); > + sha256_update(&sctx, map + i, desc->length); > + sha256_final(&sctx, sha256); > + if (memcmp(sha256, desc->sha256, 32) == 0) > + break; > + } > + if (i >= size) { > + memunmap(map); > + return -ENOENT; > + } > + > + pr_info("Found EFI embedded fw '%s'\n", desc->name);
Otherwise looks good.
Luis
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