On Wed 2016-03-16 15:47:04, Jessica Yu wrote:
> For livepatch modules, copy Elf section, symbol, and string information
> from the load_info struct in the module loader. Persist copies of the
> original symbol table and string table.
>
> Livepatch manages its own relocation sections in order to reuse module
> loader code to write relocations. Livepatch modules must preserve Elf
> information such as section indices in order to apply livepatch relocation
> sections using the module loader's apply_relocate_add() function.
>
> In order to apply livepatch relocation sections, livepatch modules must
> keep a complete copy of their original symbol table in memory. Normally, a
> stripped down copy of a module's symbol table (containing only "core"
> symbols) is made available through module->core_symtab. But for livepatch
> modules, the symbol table copied into memory on module load must be exactly
> the same as the symbol table produced when the patch module was compiled.
> This is because the relocations in each livepatch relocation section refer
> to their respective symbols with their symbol indices, and the original
> symbol indices (and thus the symtab ordering) must be preserved in order
> for apply_relocate_add() to find the right symbol.
>
> Signed-off-by: Jessica Yu <jeyu@xxxxxxxxxx>
> --- a/kernel/module.c
> +++ b/kernel/module.c
> @@ -1971,6 +1971,82 @@ static void module_enable_nx(const struct module *mod) { }
> static void module_disable_nx(const struct module *mod) { }
> #endif
>
> +#ifdef CONFIG_LIVEPATCH
> +/*
> + * Persist Elf information about a module. Copy the Elf header,
> + * section header table, section string table, and symtab section
> + * index from info to mod->klp_info.
> + */
> +static int copy_module_elf(struct module *mod, struct load_info *info)
> +{
> + unsigned int size, symndx;
> + int ret;
> +
> + size = sizeof(*mod->klp_info);
> + mod->klp_info = kmalloc(size, GFP_KERNEL);
> + if (mod->klp_info == NULL)
> + return -ENOMEM;
> +
> + /* Elf header */
> + size = sizeof(Elf_Ehdr);
It seems that you are going to do one more respin. Please, use
the size of the struct member here:
size = sizeof(mod->klp_info->hdr);
> + memcpy(&mod->klp_info->hdr, info->hdr, size);
> +
> + /* Elf section header table */
> + size = sizeof(Elf_Shdr) * info->hdr->e_shnum;
and here
size = sizeof(*info->sechdrs) * info->hdr->e_shnum;
> + mod->klp_info->sechdrs = kmalloc(size, GFP_KERNEL);
> + if (mod->klp_info->sechdrs == NULL) {
> + ret = -ENOMEM;
> + goto free_info;
> + }
> + memcpy(mod->klp_info->sechdrs, info->sechdrs, size);
Best Regards,
Petr
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