Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753208Ab3DKFd3 (ORCPT ); Thu, 11 Apr 2013 01:33:29 -0400 Received: from intranet.asianux.com ([58.214.24.6]:6205 "EHLO intranet.asianux.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750870Ab3DKFd2 (ORCPT ); Thu, 11 Apr 2013 01:33:28 -0400 X-Spam-Score: -100.8 Message-ID: <51664B04.7000207@asianux.com> Date: Thu, 11 Apr 2013 13:32:52 +0800 From: Chen Gang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Rusty Russell CC: Stephen Boyd , Andrew Morton , "linux-kernel@vger.kernel.org" Subject: [PATCH v2] kernel: kallsyms: memory override issue, need check destination buffer length References: <51662AC7.1090004@asianux.com> <87eheh4sls.fsf@rustcorp.com.au> In-Reply-To: <87eheh4sls.fsf@rustcorp.com.au> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4148 Lines: 124 We don't export any symbols > 128 characters, but if we did then kallsyms_expand_symbol() would overflow the buffer handed to it. So we need check destination buffer length when copying. the related test: if we define an EXPORT function which name more than 128. will panic when call kallsyms_lookup_name by init_kprobes on booting. after check the length (provide this patch), it is ok. Implementaion: add additional destination buffer length parameter (maxlen) if uncompressed string is too long (>= maxlen), it will be truncated. not check the parameters whether valid, since it is a static function. Signed-off-by: Chen Gang --- kernel/kallsyms.c | 26 ++++++++++++++++++-------- 1 files changed, 18 insertions(+), 8 deletions(-) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 2169fee..43d8150 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -84,9 +84,11 @@ static int is_ksym_addr(unsigned long addr) /* * Expand a compressed symbol data into the resulting uncompressed string, + * if uncompressed string is too long (>= maxlen), it will be truncated, * given the offset to where the symbol is in the compressed stream. */ -static unsigned int kallsyms_expand_symbol(unsigned int off, char *result) +static unsigned int kallsyms_expand_symbol(unsigned int off, + char *result, size_t maxlen) { int len, skipped_first = 0; const u8 *tptr, *data; @@ -113,15 +115,20 @@ static unsigned int kallsyms_expand_symbol(unsigned int off, char *result) while (*tptr) { if (skipped_first) { + if (maxlen <= 1) + goto tail; *result = *tptr; result++; + maxlen--; } else skipped_first = 1; tptr++; } } - *result = '\0'; +tail: + if (maxlen) + *result = '\0'; /* Return to offset to the next symbol. */ return off; @@ -176,7 +183,7 @@ unsigned long kallsyms_lookup_name(const char *name) unsigned int off; for (i = 0, off = 0; i < kallsyms_num_syms; i++) { - off = kallsyms_expand_symbol(off, namebuf); + off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); if (strcmp(namebuf, name) == 0) return kallsyms_addresses[i]; @@ -195,7 +202,7 @@ int kallsyms_on_each_symbol(int (*fn)(void *, const char *, struct module *, int ret; for (i = 0, off = 0; i < kallsyms_num_syms; i++) { - off = kallsyms_expand_symbol(off, namebuf); + off = kallsyms_expand_symbol(off, namebuf, ARRAY_SIZE(namebuf)); ret = fn(data, namebuf, NULL, kallsyms_addresses[i]); if (ret != 0) return ret; @@ -294,7 +301,8 @@ const char *kallsyms_lookup(unsigned long addr, pos = get_symbol_pos(addr, symbolsize, offset); /* Grab name */ - kallsyms_expand_symbol(get_symbol_offset(pos), namebuf); + kallsyms_expand_symbol(get_symbol_offset(pos), + namebuf, ARRAY_SIZE(namebuf)); if (modname) *modname = NULL; return namebuf; @@ -315,7 +323,8 @@ int lookup_symbol_name(unsigned long addr, char *symname) pos = get_symbol_pos(addr, NULL, NULL); /* Grab name */ - kallsyms_expand_symbol(get_symbol_offset(pos), symname); + kallsyms_expand_symbol(get_symbol_offset(pos), + symname, ARRAY_SIZE(symname)); return 0; } /* See if it's in a module. */ @@ -333,7 +342,8 @@ int lookup_symbol_attrs(unsigned long addr, unsigned long *size, pos = get_symbol_pos(addr, size, offset); /* Grab name */ - kallsyms_expand_symbol(get_symbol_offset(pos), name); + kallsyms_expand_symbol(get_symbol_offset(pos), + name, ARRAY_SIZE(name)); modname[0] = '\0'; return 0; } @@ -463,7 +473,7 @@ static unsigned long get_ksymbol_core(struct kallsym_iter *iter) iter->type = kallsyms_get_symbol_type(off); - off = kallsyms_expand_symbol(off, iter->name); + off = kallsyms_expand_symbol(off, iter->name, ARRAY_SIZE(iter->name)); return off - iter->nameoff; } -- 1.7.7.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/