From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 48) id 930A93839415; Mon, 16 May 2022 14:14:05 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 930A93839415 From: "eike@sf-mail.de" To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/104069] -Werror=use-after-free false positive on elfutils-0.186 Date: Mon, 16 May 2022 14:14:05 +0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: middle-end X-Bugzilla-Version: 12.0 X-Bugzilla-Keywords: diagnostic X-Bugzilla-Severity: normal X-Bugzilla-Who: eike@sf-mail.de X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: cc Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-BeenThere: gcc-bugs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-bugs mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 16 May 2022 14:14:05 -0000 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104069 Rolf Eike Beer changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |eike@sf-mail.de --- Comment #23 from Rolf Eike Beer --- Using gcc12 from 4943b75e9f06f0b64ed541430bb7fbccf55fc552. $ cat rea.c #include char * compact_buffer(char *inbuf, size_t oldlen, size_t k) { char *foo; #ifdef WARN char **buf =3D &foo; #endif foo =3D realloc(inbuf, k); if (foo =3D=3D NULL) { #if defined(WARN) && defined(WARN2) foo =3D inbuf; return inbuf; #else return inbuf; #endif } return foo; } $ gcc-12.0.1 -c -Wuse-after-free=3D3 -Irepos/Qsmtp/include rea.c $ gcc-12.0.1 -c -DWARN -Wuse-after-free=3D2 -Irepos/Qsmtp/include rea.c rea.c: In function 'compact_buffer': rea.c:17:24: warning: pointer 'inbuf' may be used after 'realloc' [-Wuse-after-free] 17 | return inbuf; | ^~~~~ rea.c:11:15: note: call to 'realloc' here 11 | foo =3D realloc(inbuf, k); | ^~~~~~~~~~~~~~~~~ $ gcc-12.0.1 -c -DWARN -DWARN2 -Wuse-after-free=3D2 -Irepos/Qsmtp/include r= ea.c rea.c: In function 'compact_buffer': rea.c:15:24: warning: pointer 'inbuf' may be used after 'realloc' [-Wuse-after-free] 15 | return inbuf; | ^~~~~ rea.c:11:15: note: call to 'realloc' here 11 | foo =3D realloc(inbuf, k); | ^~~~~~~~~~~~~~~~~ rea.c:14:21: warning: pointer 'inbuf' may be used after 'realloc' [-Wuse-after-free] 14 | foo =3D inbuf; | ~~~~^~~~~~~ rea.c:11:15: note: call to 'realloc' here 11 | foo =3D realloc(inbuf, k); | ^~~~~~~~~~~~~~~~~=