Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752026AbaL3JE0 (ORCPT ); Tue, 30 Dec 2014 04:04:26 -0500 Received: from LGEMRELSE6Q.lge.com ([156.147.1.121]:45280 "EHLO lgemrelse6q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751495AbaL3JEW (ORCPT ); Tue, 30 Dec 2014 04:04:22 -0500 X-Original-SENDERIP: 10.177.222.235 X-Original-MAILFROM: namhyung@kernel.org Date: Tue, 30 Dec 2014 18:05:33 +0900 From: Namhyung Kim To: David Ahern Cc: Masami Hiramatsu , Arnaldo Carvalho de Melo , LKML , Mark Wielaard Subject: Re: perf-probe crash in dwarf_getcfi_elf Message-ID: <20141230090533.GH6081@sejong> References: <54A22C76.9000403@gmail.com> <20141230084708.GG6081@sejong> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20141230084708.GG6081@sejong> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 30, 2014 at 05:47:08PM +0900, Namhyung Kim wrote: > On Mon, Dec 29, 2014 at 09:39:18PM -0700, David Ahern wrote: > > Hi Namhyung: > > > > Using perf-probe from top of Linus' tree I get a segfault on both Fedora 16 > > and 18 (does not crash on Fedora 20). Command used is: > > > > perf probe -x /lib64/libc-2.14.90.so -a 'malloc size=%di' > > > > git bisect points to: > > > > commit 03d89412981a7681971bc77edba1669595763030 > > Author: Namhyung Kim > > Date: Mon Apr 7 16:05:48 2014 +0900 > > > > perf probe: Use dwarf_getcfi_elf() instead of dwarf_getcfi() > > > > It seems to be related to below commit in elfutils. We might need to > check .eh_frame section has SHT_PROGBITS. Will send a patch soon. >From f56964e74d60a9921214d0e2e5c3d082f5a910c1 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Tue, 30 Dec 2014 17:47:47 +0900 Subject: [PATCH] perf probe: Fix a segfault on old libdw David reported that perf can segfault when adding an uprobe event like this: $ perf probe -x /lib64/libc-2.14.90.so -a 'malloc size=%di' (gdb) bt #0 parse_eh_frame_hdr (hdr=0x0, hdr_size=2596, hdr_vaddr=71788, ehdr=0x7fffffffd390, eh_frame_vaddr= 0x7fffffffd378, table_entries=0x8808d8, table_encoding=0x8808e0 "") at dwarf_getcfi_elf.c:79 #1 0x000000385f81615a in getcfi_scn_eh_frame (hdr_vaddr=71788, hdr_scn=0x8839b0, shdr=0x7fffffffd2f0, scn=, ehdr=0x7fffffffd390, elf=0x882b30) at dwarf_getcfi_elf.c:231 #2 getcfi_shdr (ehdr=0x7fffffffd390, elf=0x882b30) at dwarf_getcfi_elf.c:283 #3 dwarf_getcfi_elf (elf=0x882b30) at dwarf_getcfi_elf.c:309 #4 0x00000000004d5bac in debuginfo__find_probes (pf=0x7fffffffd4f0, dbg=Unhandled dwarf expression opcode 0xfa) at util/probe-finder.c:993 #5 0x00000000004d634a in debuginfo__find_trace_events (dbg=0x880840, pev=, tevs=0x880f88, max_tevs=) at util/probe-finder.c:1200 #6 0x00000000004aed6b in try_to_find_probe_trace_events (target=0x881b20 "/lib64/libpthread-2.14.90.so", max_tevs=128, tevs=0x880f88, pev=0x859b30) at util/probe-event.c:482 #7 convert_to_probe_trace_events (target=0x881b20 "/lib64/libpthread-2.14.90.so", max_tevs=128, tevs=0x880f88, pev=0x859b30) at util/probe-event.c:2356 #8 add_perf_probe_events (pevs=, npevs=1, max_tevs=128, target=0x881b20 "/lib64/libpthread-2.14.90.so", force_add=false) at util/probe-event.c:2391 #9 0x000000000044014f in __cmd_probe (argc=, argv=0x7fffffffe2f0, prefix=Unhandled dwarf expression opcode 0xfa) at at builtin-probe.c:488 #10 0x0000000000440313 in cmd_probe (argc=5, argv=0x7fffffffe2f0, prefix=) at builtin-probe.c:506 #11 0x000000000041d133 in run_builtin (p=0x805680, argc=5, argv=0x7fffffffe2f0) at perf.c:341 #12 0x000000000041c8b2 in handle_internal_command (argv=, argc=) at perf.c:400 #13 run_argv (argv=, argcp=) at perf.c:444 #14 main (argc=5, argv=0x7fffffffe2f0) at perf.c:559 And I found a related commit (5704c8c4fa71 "getcfi_scn_eh_frame: Don't crash and burn when .eh_frame bits aren't there.") in elfutils that can lead to a unexpected crash like this. To safely use the function, it needs to check the .eh_frame section is a PROGBITS type. Reported-by: David Ahern Cc: Mark Wielaard Signed-off-by: Namhyung Kim --- tools/perf/util/probe-finder.c | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c index c7918f83b300..b5247d777f0e 100644 --- a/tools/perf/util/probe-finder.c +++ b/tools/perf/util/probe-finder.c @@ -989,8 +989,24 @@ static int debuginfo__find_probes(struct debuginfo *dbg, int ret = 0; #if _ELFUTILS_PREREQ(0, 142) + Elf *elf; + GElf_Ehdr ehdr; + GElf_Shdr shdr; + /* Get the call frame information from this dwarf */ - pf->cfi = dwarf_getcfi_elf(dwarf_getelf(dbg->dbg)); + elf = dwarf_getelf(dbg->dbg); + if (elf == NULL) + return -EINVAL; + + if (gelf_getehdr(elf, &ehdr) == NULL) + return -EINVAL; + + if (elf_section_by_name(elf, &ehdr, &shdr, ".eh_frame", NULL) && + shdr.sh_type == SHT_PROGBITS) { + pf->cfi = dwarf_getcfi_elf(elf); + } else { + pf->cfi = dwarf_getcfi(dbg->dbg); + } #endif off = 0; -- 2.1.3 -- 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/