Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753436AbaG2Mrv (ORCPT ); Tue, 29 Jul 2014 08:47:51 -0400 Received: from mail-yh0-f48.google.com ([209.85.213.48]:49257 "EHLO mail-yh0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750933AbaG2Mrt (ORCPT ); Tue, 29 Jul 2014 08:47:49 -0400 From: Jianyu Zhan To: mingo@kernel.org Cc: masami.hiramatsu.pt@hitachi.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Jianyu Zhan Subject: Re: [PATCH RESEND] kprobes: be more permissive when user specifies both symbol name and address Date: Tue, 29 Jul 2014 20:47:38 +0800 Message-Id: <1406638058-7761-1-git-send-email-nasa4836@gmail.com> X-Mailer: git-send-email 2.0.0 In-Reply-To: <20140728105156.GB14215@gmail.com> References: <20140728105156.GB14215@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, Ingo, Here is the new patch with typo fixed. Thanks. ---8<--- Currently, if user specifies both symbol name and address, we just bail out. This might be too rude. This patch makes it give more tolerance. If both are specified, check address first, if the symbol found does not match the one user specify, print a waring. If not found, return -ENOENT, because some symbols might have muplitple instances, we don't bother to check symbol name. --- Documentation/kprobes.txt | 4 +++- kernel/kprobes.c | 32 +++++++++++++++++++++++++++++--- 2 files changed, 32 insertions(+), 4 deletions(-) diff --git a/Documentation/kprobes.txt b/Documentation/kprobes.txt index 4bbeca8..663b5ad 100644 --- a/Documentation/kprobes.txt +++ b/Documentation/kprobes.txt @@ -358,7 +358,9 @@ to install a probepoint is known. This field is used to calculate the probepoint. 3. Specify either the kprobe "symbol_name" OR the "addr". If both are -specified, kprobe registration will fail with -EINVAL. +specified, only check "addr", because some symbols might have multiple +instances. If neither is specified, kprobe registration will fail +with -EINVAL. 4. With CISC architectures (such as i386 and x86_64), the kprobes code does not validate if the kprobe.addr is at an instruction boundary. diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 734e9a7..9768608 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1358,15 +1358,41 @@ static bool within_kprobe_blacklist(unsigned long addr) static kprobe_opcode_t *kprobe_addr(struct kprobe *p) { kprobe_opcode_t *addr = p->addr; + char namebuf[KSYM_NAME_LEN]; + const char *sym_name = NULL; + unsigned long offset; - if ((p->symbol_name && p->addr) || - (!p->symbol_name && !p->addr)) + if (!p->symbol_name && !p->addr) goto invalid; - if (p->symbol_name) { + /* + * Some symbols might have multiple instances, + * so if both are specified, only check address. + */ + if (unlikely(p->addr && p->symbol_name)) { + sym_name = kallsyms_lookup((unsigned long)(p->addr), + NULL, &offset, NULL, namebuf); + if (!sym_name) + return ERR_PTR(-ENOENT); + + if (strncmp(sym_name, p->symbol_name, KSYM_NAME_LEN) + || offset != p->offset) { + pr_err("Incorrect symbol or offset, should be " + "symbol=%s, offset=%ld.\n", sym_name, offset); + goto invalid; + } + } else if (p->symbol_name) { + /* Only symbol case */ kprobe_lookup_name(p->symbol_name, addr); if (!addr) return ERR_PTR(-ENOENT); + } else { + /* + * Only address case. + * Since we later will do a sanity check of the + * address range in check_kprobe_address_safe(), + * do nothing here. + */ } addr = (kprobe_opcode_t *)(((char *)addr) + p->offset); -- 2.0.0 -- 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/