From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 100040 invoked by alias); 19 Jun 2018 08:59:58 -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 88980 invoked by uid 89); 19 Jun 2018 08:59:36 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=AWL,BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,SPF_PASS autolearn=ham version=3.3.2 spammy=Space X-HELO: relay.fit.cvut.cz Received: from relay.fit.cvut.cz (HELO relay.fit.cvut.cz) (147.32.232.237) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 19 Jun 2018 08:59:31 +0000 Received: from imap.fit.cvut.cz (imap.fit.cvut.cz [IPv6:2001:718:2:2901:0:0:0:238] (may be forged)) by relay.fit.cvut.cz (8.15.2/8.15.2) with ESMTPS id w5J8xN5P013621 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=OK); Tue, 19 Jun 2018 10:59:25 +0200 (CEST) (envelope-from jan.vrany@fit.cvut.cz) Received: from sao (0279192e.bb.sky.com [2.121.25.46] (may be forged)) (authenticated bits=0 as user vranyj1) by imap.fit.cvut.cz (8.15.2/8.15.2) with ESMTPSA id w5J8xMk6083176 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Tue, 19 Jun 2018 10:59:23 +0200 (CEST) (envelope-from jan.vrany@fit.cvut.cz) Message-ID: Subject: Re: [PATCH] Fix segfault when invoking -var-info-path-expression on a dynamic varobj From: Jan Vrany To: Simon Marchi , gdb-patches@sourceware.org Date: Tue, 19 Jun 2018 08:59:00 -0000 In-Reply-To: References: <20180604131503.31945-1-jan.vrany@fit.cvut.cz> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-SW-Source: 2018-06/txt/msg00472.txt.bz2 On Mon, 2018-06-18 at 20:42 -0400, Simon Marchi wrote: > On 2018-06-04 09:15 AM, Jan Vrany wrote: > > Invoking -var-info-path-expression on a dynamic varobj lead either > > in wrong > > (nonsense) result or to a segmentation fault in > > cplus_describe_child(). > > This was caused by the fact that varobj_get_path_expr() called > > cplus_path_expr_of_child() ignoring the fact the parent of the > > variable > > is dynamic. Then, cplus_describe_child() accessed the underlaying C > > type > > members by index, causing (i) either wrong (nonsense) expression > > being > > returned (since dynamic child may be completely arbibtrary value) > > or (ii) segmentation fault (in case the index higher than number of > > underlaying C type members. > > > > This fixes the problem by checking whether a varobj is a child of a > > dynamic > > varobj and, if so, reporting an error to MI consumer as described > > in > > the documentation. > > Hi Jan, > > Thanks for the patch. I think we should also handle the indirect > children > of dynamic objects. When trying this test program: > > #include > struct foo { int a; }; > int main() { > std::vector vec; > vec.push_back({ 1 }); > return 0; > } > > With the following MI commands: > > -enable-pretty-printing > b 6 > r > -var-create - * vec > -var-list-children var1 > -var-list-children var1.[0] > -var-list-children var1.[0].public > -var-info-path-expression var1.[0].public.a > > I get this: > > ~"/home/simark/src/binutils-gdb/gdb/varobj.c:969: internal-error: > const char* varobj_get_path_expr(const varobj*): Assertion > `!varobj_is_dynamic_p(var->parent)' failed..." > Hi Simon, good catch! Will fix that. > I noted some small formatting nits below. Thanks! I appreciate the patience you have with me. I will address your comments and send new version. Best, Jan > > > gdb/ChangeLog: > > > > * mi/mi-cmd-var.c: Report an error if varobj is a child of > > dynamic > > varobj as stated in documentation. > > * varobj.c: New assert. > > > > gdb/testsuite/Changelog: > > > > * gdb.pythonpy-mi-var-info-path-expression.c: New file. > > You are missing a slash here (and in the ChangeLog file itself). > > > * gdb.python/py-mi-var-info-path-expression.py: New file. > > * gdb.python/py-mi-var-info-path-expression.exp: New file. > > --- > > gdb/ChangeLog | 6 ++ > > gdb/mi/mi-cmd-var.c | 5 ++ > > gdb/testsuite/ChangeLog | 6 ++ > > .../py-mi-var-info-path-expression.c | 40 ++++++++++ > > .../py-mi-var-info-path-expression.exp | 77 > > +++++++++++++++++++ > > .../py-mi-var-info-path-expression.py | 45 +++++++++++ > > gdb/varobj.c | 6 +- > > 7 files changed, 184 insertions(+), 1 deletion(-) > > create mode 100644 gdb/testsuite/gdb.python/py-mi-var-info-path- > > expression.c > > create mode 100644 gdb/testsuite/gdb.python/py-mi-var-info-path- > > expression.exp > > create mode 100644 gdb/testsuite/gdb.python/py-mi-var-info-path- > > expression.py > > > > diff --git a/gdb/ChangeLog b/gdb/ChangeLog > > index a292f4c056..fc5edb9a9e 100644 > > --- a/gdb/ChangeLog > > +++ b/gdb/ChangeLog > > @@ -1,3 +1,9 @@ > > +2018-06-04 Jan Vrany > > + > > + * mi/mi-cmd-var.c: Report an error if varobj is a child of > > dynamic > > + varobj as stated in documentation. > > + * varobj.c: New assert. > > + > > 2018-06-04 Pedro Alves > > > > * darwin-nat.c (darwin_ops): Delete. > > diff --git a/gdb/mi/mi-cmd-var.c b/gdb/mi/mi-cmd-var.c > > index 38c59c7e66..f278281023 100644 > > --- a/gdb/mi/mi-cmd-var.c > > +++ b/gdb/mi/mi-cmd-var.c > > @@ -438,6 +438,11 @@ mi_cmd_var_info_path_expression (const char > > *command, char **argv, int argc) > > > > /* Get varobj handle, if a valid var obj name was specified. */ > > var = varobj_get_handle (argv[0]); > > + > > + /* -var-info-path-expression is currently not valid for children > > of > > + a dynamic varobj */ > > Finish the sentence with a period. > > > diff --git a/gdb/varobj.c b/gdb/varobj.c > > index a0df485ae9..87bfd44549 100644 > > --- a/gdb/varobj.c > > +++ b/gdb/varobj.c > > @@ -962,9 +962,13 @@ varobj_get_path_expr (const struct varobj > > *var) > > /* For root varobjs, we initialize path_expr > > when creating varobj, so here it should be > > child varobj. */ > > - struct varobj *mutable_var = (struct varobj *) var; > > gdb_assert (!is_root_p (var)); > > > > + /* Computation of full rooted expression for children of > > dynamic > > + varobjs is not supported. */ > > Two spaces after the final period (before the */). > > > + gdb_assert (!varobj_is_dynamic_p(var->parent)); > > Space after varobj_is_dynamic_p. > > Thanks, > > Simon