From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20621 invoked by alias); 23 Mar 2019 20:10:39 -0000 Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org Received: (qmail 20609 invoked by uid 89); 23 Mar 2019 20:10:38 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-22.6 required=5.0 tests=AWL,BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,KAM_STOCKGEN,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.1 spammy=Before X-HELO: mailsec119.isp.belgacom.be Received: from mailsec119.isp.belgacom.be (HELO mailsec119.isp.belgacom.be) (195.238.20.115) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Sat, 23 Mar 2019 20:10:36 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=skynet.be; i=@skynet.be; q=dns/txt; s=securemail; t=1553371836; x=1584907836; h=message-id:subject:from:to:date:in-reply-to:references: mime-version:content-transfer-encoding; bh=wbn+jxReHLhe/M8TVm7Ac49E8+2SjvcVX741vgVnoW0=; b=T2+w6CugFL90VkyOwCm+TZWtZ8m6Qp2Ghwhx178aptisz11IPrGu73Rm l8BPNuHDAQOJuIDKuDCrtex/7mBRKQ==; Received: from unknown (HELO md) ([109.130.122.147]) by relay.skynet.be with ESMTP/TLS/AES256-GCM-SHA384; 23 Mar 2019 21:10:34 +0100 Message-ID: <1553371834.1504.1.camel@skynet.be> Subject: Re: [RFQ] Fix buffer overflow regression due to minsym malloc-ed instead of obstack-ed. From: Philippe Waroquiers To: gdb-patches@sourceware.org Date: Sat, 23 Mar 2019 20:10:00 -0000 In-Reply-To: <20190323200635.29070-1-philippe.waroquiers@skynet.be> References: <20190323200635.29070-1-philippe.waroquiers@skynet.be> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2019-03/txt/msg00507.txt.bz2 Typo in the subject: s/RFQ/RFA/ Thanks Philippe On Sat, 2019-03-23 at 21:06 +0100, Philippe Waroquiers wrote: > Valgrind detects the following error in a bunch of tests, > e.g. in gdb.base/foll-fork.exp. > > ==15155== VALGRIND_GDB_ERROR_BEGIN > ==15155== Invalid read of size 8 > ==15155== at 0x55BE04: minimal_symbol_upper_bound(bound_minimal_symbol) (minsyms.c:1504) > ==15155== by 0x3B2E9C: find_pc_partial_function(unsigned long, char const**, unsigned long*, unsigned long*, block const**) (blockframe.c:340) > ==15155== by 0x3B3135: find_function_entry_range_from_pc(unsigned long, char const**, unsigned long*, unsigned long*) (blockframe.c:385) > ==15155== by 0x4F5597: fill_in_stop_func(gdbarch*, execution_control_state*) [clone .part.16] (infrun.c:4124) > ==15155== by 0x4FBE01: fill_in_stop_func (infrun.c:7636) > ==15155== by 0x4FBE01: process_event_stop_test(execution_control_state*) (infrun.c:6279) > ... > ==15155== Address 0x715bec8 is 0 bytes after a block of size 2,952 alloc'd > ==15155== at 0x4C2E2B3: realloc (vg_replace_malloc.c:836) > ==15155== by 0x405F2C: xrealloc (common-utils.c:62) > ==15155== by 0x55BA4E: xresizevec (poison.h:170) > ==15155== by 0x55BA4E: minimal_symbol_reader::install() (minsyms.c:1399) > ==15155== by 0x4981C7: elf_read_minimal_symbols (elfread.c:1165) > ... > > This seems to be a regression created by: > commit 042d75e42c5572f333e0e06dabd3c5c4afab486c > Author: Tom Tromey > AuthorDate: Sat Mar 2 12:29:48 2019 -0700 > Commit: Tom Tromey > CommitDate: Fri Mar 15 16:02:10 2019 -0600 > > Allocate minimal symbols with malloc > > Before this commit, the array of 'struct minimal_symbol' > contained a last element that was a "null symbol". The comment in > minimal_symbol_reader::install was: > /* We also terminate the minimal symbol table with a "null symbol", > which is *not* included in the size of the table. This makes it > easier to find the end of the table when we are handed a pointer > to some symbol in the middle of it. Zero out the fields in the > "null symbol" allocated at the end of the array. Note that the > symbol count does *not* include this null symbol, which is why it > is indexed by mcount and not mcount-1. */ > > memset (&msymbols[mcount], 0, sizeof (struct minimal_symbol)); > > However, minimal_symbol_upper_bound was still based on the assumption > that the array of minsym is terminated by a minsym with a null symbol: > it is looping with: > for (i = 1; MSYMBOL_LINKAGE_NAME (msymbol + i) != NULL; i++) > > Replace this NULL comparison by a logic that calculates how > many msymbol are following the msymbols from which we are starting from. > > Tested on debian/amd64, natively and under valgrind. > > Note that a bunch of comments in minimal_symbol_reader::install > are still referring to allocations being done in obstack. These > comments seem obsolete. I have not fixed them, as I have not > understood what they are explaining (e.g. related to language > auto, demangling, etc : I have not seen where all this is done). > > gdb/ChangeLog > 2019-03-23 Philippe Waroquiers > > * minsyms.c (minimal_symbol_upper_bound): Fix buffer overflow > by computing the nr of symbols after msymbol. > --- > gdb/minsyms.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/gdb/minsyms.c b/gdb/minsyms.c > index b95e9ef6e8..f56663460d 100644 > --- a/gdb/minsyms.c > +++ b/gdb/minsyms.c > @@ -1501,7 +1501,10 @@ minimal_symbol_upper_bound (struct bound_minimal_symbol minsym) > > msymbol = minsym.minsym; > section = MSYMBOL_SECTION (msymbol); > - for (i = 1; MSYMBOL_LINKAGE_NAME (msymbol + i) != NULL; i++) > + int n_after_msymbol = minsym.objfile->per_bfd->minimal_symbol_count > + - (msymbol - minsym.objfile->per_bfd->msymbols.get ()) > + - 1; > + for (i = 1; i < n_after_msymbol; i++) > { > if ((MSYMBOL_VALUE_RAW_ADDRESS (msymbol + i) > != MSYMBOL_VALUE_RAW_ADDRESS (msymbol)) > @@ -1510,7 +1513,7 @@ minimal_symbol_upper_bound (struct bound_minimal_symbol minsym) > } > > obj_section = MSYMBOL_OBJ_SECTION (minsym.objfile, minsym.minsym); > - if (MSYMBOL_LINKAGE_NAME (msymbol + i) != NULL > + if (i < n_after_msymbol > && (MSYMBOL_VALUE_ADDRESS (minsym.objfile, msymbol + i) > < obj_section_endaddr (obj_section))) > result = MSYMBOL_VALUE_ADDRESS (minsym.objfile, msymbol + i);