From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 69D403893659; Tue, 28 Nov 2023 09:31:37 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 69D403893659 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1701163897; bh=bYedHEa30OPWqi7uPdA0VgcjfH3e4ZxgEu9QG9G1x8w=; h=From:To:Subject:Date:In-Reply-To:References:From; b=NFWSZH4NMj52e1h/+iGz99H9E6yke1hLS+KYOFQ0N0YFeYfVptXQ7nGlBv3MpG5LC drWIpCUg7cS0tNiBnSw0NDWRgOg+RlMjBoMHWkftGm4gOj5Y8yUaNpuLSTq+VIVth0 fFsOnK6ModP1H3qOWh+wsj91ttL9bwCbeK7JdT7U= From: "cvs-commit at gcc dot gnu.org" To: gdb-prs@sourceware.org Subject: [Bug gdb/30547] [gdb, s390x, ppc64] segfault in for_each_block Date: Tue, 28 Nov 2023 09:31:35 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gdb X-Bugzilla-Component: gdb X-Bugzilla-Version: 13.1 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: cvs-commit at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P2 X-Bugzilla-Assigned-To: unassigned at sourceware dot org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://sourceware.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 List-Id: https://sourceware.org/bugzilla/show_bug.cgi?id=3D30547 --- Comment #8 from Sourceware Commits --- The master branch has been updated by Tom de Vries : https://sourceware.org/git/gitweb.cgi?p=3Dbinutils-gdb.git;h=3Df9582a22dba7= 47ff0905f4c1a80d84f677eeb928 commit f9582a22dba747ff0905f4c1a80d84f677eeb928 Author: Tom de Vries Date: Tue Nov 28 10:31:25 2023 +0100 [gdb] Fix segfault in for_each_block, part 1 When running test-case gdb.base/vfork-follow-parent.exp on powerpc64 (likewise on s390x), I run into: ... (gdb) PASS: gdb.base/vfork-follow-parent.exp: \ exec_file=3Dvfork-follow-parent-exit: target-non-stop=3Don: non-stop= =3Doff: \ resolution_method=3Dschedule-multiple: print unblock_parent =3D 1 continue^M Continuing.^M Reading symbols from vfork-follow-parent-exit...^M ^M ^M Fatal signal: Segmentation fault^M ----- Backtrace -----^M 0x1027d3e7 gdb_internal_backtrace_1^M src/gdb/bt-utils.c:122^M 0x1027d54f _Z22gdb_internal_backtracev^M src/gdb/bt-utils.c:168^M 0x1057643f handle_fatal_signal^M src/gdb/event-top.c:889^M 0x10576677 handle_sigsegv^M src/gdb/event-top.c:962^M 0x3fffa7610477 ???^M 0x103f2144 for_each_block^M src/gdb/dcache.c:199^M 0x103f235b _Z17dcache_invalidateP13dcache_struct^M src/gdb/dcache.c:251^M 0x10bde8c7 _Z24target_dcache_invalidatev^M src/gdb/target-dcache.c:50^M ... or similar. The root cause for the segmentation fault is that linux_is_uclinux give= s an incorrect result: it should always return false, given that we're runni= ng on a regular linux system, but instead it returns first true, then false. In more detail, the segmentation fault happens as follows: - a program space with an address space is created - a second program space is about to be created. maybe_new_address_space is called, and because linux_is_uclinux returns true, maybe_new_address_space returns false, and no new address space is created - a second program space with the same address space is created - a program space is deleted. Because linux_is_uclinux now returns fals= e, gdbarch_has_shared_address_space (current_inferior ()->arch ()) retur= ns false, and the address space is deleted - when gdb uses the address space of the remaining program space, we run into the segfault, because the address space is deleted. Hardcoding linux_is_uclinux to false makes the test-case pass. We leave addressing the root cause for the following commit in this ser= ies. For now, prevent the segmentation fault by making the address space a refcounted object. This was already suggested here [1]: ... A better solution might be to have the address spaces be reference coun= ted ... Tested on top of trunk on x86_64-linux and ppc64le-linux. Tested on top of gdb-14-branch on ppc64-linux. Co-Authored-By: Simon Marchi PR gdb/30547 Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=3D30547 [1] https://sourceware.org/pipermail/gdb-patches/2023-October/202928.ht= ml --=20 You are receiving this mail because: You are on the CC list for the bug.=