From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 75227 invoked by alias); 19 Jun 2018 00:42:53 -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 75211 invoked by uid 89); 19 Jun 2018 00:42:52 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 spammy= X-HELO: simark.ca Received: from simark.ca (HELO simark.ca) (158.69.221.121) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Tue, 19 Jun 2018 00:42:51 +0000 Received: from [10.0.0.11] (unknown [192.222.164.54]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by simark.ca (Postfix) with ESMTPSA id EC02D1E481; Mon, 18 Jun 2018 20:42:48 -0400 (EDT) Subject: Re: [PATCH] Fix segfault when invoking -var-info-path-expression on a dynamic varobj To: Jan Vrany , gdb-patches@sourceware.org References: <20180604131503.31945-1-jan.vrany@fit.cvut.cz> From: Simon Marchi Message-ID: Date: Tue, 19 Jun 2018 00:42:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.8.0 MIME-Version: 1.0 In-Reply-To: <20180604131503.31945-1-jan.vrany@fit.cvut.cz> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SW-Source: 2018-06/txt/msg00470.txt.bz2 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..." I noted some small formatting nits below. > 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