From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756576Ab2KNF4s (ORCPT ); Wed, 14 Nov 2012 00:56:48 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:55241 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756427Ab2KNFvD (ORCPT ); Wed, 14 Nov 2012 00:51:03 -0500 Message-Id: <20121114053939.282743930@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Wed, 14 Nov 2012 05:40:12 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Rusty Russell , Masaki Kimura Subject: [ 39/82] module: fix out-by-one error in kallsyms In-Reply-To: <20121114053933.726869752@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:21c:bfff:fe03:f805 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Rusty Russell commit 59ef28b1f14899b10d6b2682c7057ca00a9a3f47 upstream. 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 [bwh: Backported to 3.2: we're still using a bitmap to compress the string table] Signed-off-by: Ben Hutchings --- kernel/module.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) --- a/kernel/module.c +++ b/kernel/module.c @@ -2193,15 +2193,17 @@ static void layout_symtab(struct module src = (void *)info->hdr + symsect->sh_offset; nsrc = symsect->sh_size / sizeof(*src); - for (ndst = i = 1; i < nsrc; ++i, ++src) - if (is_core_symbol(src, info->sechdrs, info->hdr->e_shnum)) { - unsigned int j = src->st_name; + for (ndst = i = 0; i < nsrc; i++) { + if (i == 0 || + is_core_symbol(src+i, info->sechdrs, info->hdr->e_shnum)) { + unsigned int j = src[i].st_name; while (!__test_and_set_bit(j, info->strmap) && info->strtab[j]) ++j; ++ndst; } + } /* Append room for core symbols at end of core part. */ info->symoffs = ALIGN(mod->core_size, symsect->sh_addralign ?: 1); @@ -2238,14 +2240,14 @@ static void add_kallsyms(struct module * mod->core_symtab = dst = mod->module_core + info->symoffs; src = mod->symtab; - *dst = *src; - 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 = bitmap_weight(info->strmap, - dst[ndst].st_name); - ++ndst; + 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 = bitmap_weight(info->strmap, + dst[ndst].st_name); + ++ndst; + } } mod->core_num_syms = ndst;