From 59ef28b1f14899b10d6b2682c7057ca00a9a3f47 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Thu, 25 Oct 2012 10:49:25 +1030 Subject: module: fix out-by-one error in kallsyms Masaki found and patched a kallsyms issue: the last symbol in a module's symtab wasn't transferred. This is because we manually copy the zero'th entry (which is always empty) then copy the rest in a loop starting at 1, though from src[0]. His fix was minimal, I prefer to rewrite the loops in more standard form. There are two loops: one to get the size, and one to copy. Make these identical: always count entry 0 and any defined symbol in an allocated non-init section. This bug exists since the following commit was introduced. module: reduce symbol table for loaded modules (v2) commit: 4a4962263f07d14660849ec134ee42b63e95ea9a LKML: http://lkml.org/lkml/2012/10/24/27 Reported-by: Masaki Kimura Cc: stable@kernel.org --- kernel/module.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) diff --git a/kernel/module.c b/kernel/module.c index 6085f5ef88ea..6e48c3a43599 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2293,12 +2293,17 @@ static void layout_symtab(struct module *mod, struct load_info *info) src = (void *)info->hdr + symsect->sh_offset; nsrc = symsect->sh_size / sizeof(*src); + /* strtab always starts with a nul, so offset 0 is the empty string. */ + strtab_size = 1; + /* Compute total space required for the core symbols' strtab. */ - for (ndst = i = strtab_size = 1; i < nsrc; ++i, ++src) - if (is_core_symbol(src, info->sechdrs, info->hdr->e_shnum)) { - strtab_size += strlen(&info->strtab[src->st_name]) + 1; + for (ndst = i = 0; i < nsrc; i++) { + if (i == 0 || + is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum)) { + strtab_size += strlen(&info->strtab[src[i].st_name])+1; ndst++; } + } /* Append room for core symbols at end of core part. */ info->symoffs = ALIGN(mod->core_size, symsect->sh_addralign ?: 1); @@ -2332,15 +2337,15 @@ static void add_kallsyms(struct module *mod, const struct load_info *info) mod->core_symtab = dst = mod->module_core + info->symoffs; mod->core_strtab = s = mod->module_core + info->stroffs; src = mod->symtab; - *dst = *src; *s++ = 0; - for (ndst = i = 1; i < mod->num_symtab; ++i, ++src) { - if (!is_core_symbol(src, info->sechdrs, info->hdr->e_shnum)) - continue; - - dst[ndst] = *src; - dst[ndst++].st_name = s - mod->core_strtab; - s += strlcpy(s, &mod->strtab[src->st_name], KSYM_NAME_LEN) + 1; + for (ndst = i = 0; i < mod->num_symtab; i++) { + if (i == 0 || + is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum)) { + dst[ndst] = src[i]; + dst[ndst++].st_name = s - mod->core_strtab; + s += strlcpy(s, &mod->strtab[src[i].st_name], + KSYM_NAME_LEN) + 1; + } } mod->core_num_syms = ndst; } -- cgit v1.2.1