From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1039) id 37DB63858C60; Sat, 6 Jan 2024 22:26:17 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 37DB63858C60 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sourceware.org; s=default; t=1704579977; bh=IfS/2RrYWOWsKki6XwKPdRVbBHfW+J/1k8/TAZerxIo=; h=From:To:Subject:Date:From; b=hGWajAeNgNkxnbEU0P8S8QrdmTsmSY1gAg/vp+pk3bTKoLUXm9NzlE6kA6MTrg/tW Bnz2umgV841u9fLVPfWV7xIsUjRGiGshIlxXR1Ts8tiwZmOuouhoQeyBGh+KBowhLu T8VsQk+Fsui5HyHMlE1q0kkBbYTCrYJuYnVF6DHs= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: H.J. Lu To: glibc-cvs@sourceware.org Subject: [glibc] x32: Handle displacement overflow in PLT rewrite [BZ #31218] X-Act-Checkin: glibc X-Git-Author: H.J. Lu X-Git-Refname: refs/heads/master X-Git-Oldrev: b96a2eba2fcca37deea221a18c998ee0084a5d21 X-Git-Newrev: 0f9afc265a4a0f4ba658d7f71c9602a3fda3538e Message-Id: <20240106222617.37DB63858C60@sourceware.org> Date: Sat, 6 Jan 2024 22:26:17 +0000 (GMT) List-Id: https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=0f9afc265a4a0f4ba658d7f71c9602a3fda3538e commit 0f9afc265a4a0f4ba658d7f71c9602a3fda3538e Author: H.J. Lu Date: Sat Jan 6 14:03:37 2024 -0800 x32: Handle displacement overflow in PLT rewrite [BZ #31218] PLT rewrite calculated displacement with ElfW(Addr) disp = value - branch_start - JMP32_INSN_SIZE; On x32, displacement from 0xf7fbe060 to 0x401030 was calculated as unsigned int disp = 0x401030 - 0xf7fbe060 - 5; with disp == 0x8442fcb and caused displacement overflow. The PLT entry was changed to: 0xf7fbe060 <+0>: e9 cb 2f 44 08 jmp 0x401030 0xf7fbe065 <+5>: cc int3 0xf7fbe066 <+6>: cc int3 0xf7fbe067 <+7>: cc int3 0xf7fbe068 <+8>: cc int3 0xf7fbe069 <+9>: cc int3 0xf7fbe06a <+10>: cc int3 0xf7fbe06b <+11>: cc int3 0xf7fbe06c <+12>: cc int3 0xf7fbe06d <+13>: cc int3 0xf7fbe06e <+14>: cc int3 0xf7fbe06f <+15>: cc int3 x32 has 32-bit address range, but it doesn't wrap address around at 4GB, JMP target was changed to 0x100401030 (0xf7fbe060LL + 0x8442fcbLL + 5), which is above 4GB. Always use uint64_t to calculate displacement. This fixes BZ #31218. Reviewed-by: Noah Goldstein Diff: --- sysdeps/x86_64/Makefile | 8 +++++++ sysdeps/x86_64/dl-machine.h | 5 ++-- sysdeps/x86_64/tst-plt-rewrite2.c | 46 ++++++++++++++++++++++++++++++++++++ sysdeps/x86_64/tst-plt-rewritemod2.c | 32 +++++++++++++++++++++++++ 4 files changed, 89 insertions(+), 2 deletions(-) diff --git a/sysdeps/x86_64/Makefile b/sysdeps/x86_64/Makefile index 374bca80d0..836e03a224 100644 --- a/sysdeps/x86_64/Makefile +++ b/sysdeps/x86_64/Makefile @@ -186,9 +186,11 @@ endif ifeq (yes,$(have-z-mark-plt)) tests += \ tst-plt-rewrite1 \ + tst-plt-rewrite2 \ # tests modules-names += \ tst-plt-rewritemod1 \ + tst-plt-rewritemod2 \ # modules-names tst-plt-rewrite1-no-pie = yes @@ -200,6 +202,12 @@ $(objpfx)tst-plt-rewrite1.out: /dev/null $(objpfx)tst-plt-rewrite1 $(tst-plt-rewrite1-ENV) $(make-test-out) > $@ 2>&1; \ grep -q -E "changing 'bar' PLT entry in .*/elf/tst-plt-rewritemod1.so' to direct branch" $@; \ $(evaluate-test) + +tst-plt-rewrite2-no-pie = yes +LDFLAGS-tst-plt-rewrite2 = -Wl,-z,now +LDFLAGS-tst-plt-rewritemod2.so = -Wl,-z,now,-z,undefs +tst-plt-rewrite2-ENV = GLIBC_TUNABLES=glibc.cpu.plt_rewrite=2 +$(objpfx)tst-plt-rewrite2: $(objpfx)tst-plt-rewritemod2.so endif endif # $(subdir) == elf diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h index ca290ef082..2d2ce503a5 100644 --- a/sysdeps/x86_64/dl-machine.h +++ b/sysdeps/x86_64/dl-machine.h @@ -607,8 +607,9 @@ x86_64_rewrite_plt (struct link_map *map, ElfW(Addr) plt_rewrite) /* Skip ENDBR64 if IBT isn't enabled. */ if (!ibt_enabled_p) branch_start = ALIGN_DOWN (branch_start, pltent); - /* Get the displacement from the branch target. */ - ElfW(Addr) disp = value - branch_start - JMP32_INSN_SIZE; + /* Get the displacement from the branch target. NB: We must use + 64-bit integer on x32 to avoid overflow. */ + uint64_t disp = (uint64_t) value - branch_start - JMP32_INSN_SIZE; ElfW(Addr) plt_end; ElfW(Addr) pad; diff --git a/sysdeps/x86_64/tst-plt-rewrite2.c b/sysdeps/x86_64/tst-plt-rewrite2.c new file mode 100644 index 0000000000..8427df5605 --- /dev/null +++ b/sysdeps/x86_64/tst-plt-rewrite2.c @@ -0,0 +1,46 @@ +/* Test PLT rewrite with 32-bit displacement overflow. + Copyright (C) 2024 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include + +extern int (*func_p) (void); +extern void foo (void); + +int +func (void) +{ + return 0xbadbeef; +} + +void +bar (void) +{ + TEST_VERIFY (func_p == &func); + TEST_VERIFY (func_p () == 0xbadbeef); +} + +static int +do_test (void) +{ + func_p = &func; + foo (); + bar (); + return 0; +} + +#include diff --git a/sysdeps/x86_64/tst-plt-rewritemod2.c b/sysdeps/x86_64/tst-plt-rewritemod2.c new file mode 100644 index 0000000000..4a86d736b5 --- /dev/null +++ b/sysdeps/x86_64/tst-plt-rewritemod2.c @@ -0,0 +1,32 @@ +/* Check PLT rewrite with 32-bit displacement overflow. + Copyright (C) 2024 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +/* foo calls func with indirect branch via PLT. PLT rewrite shouldn't + change it to direct branch if func is too far way. */ + +#include + +int (*func_p) (void); +extern int func (void); + +void +foo (void) +{ + TEST_VERIFY (func () == 0xbadbeef); + TEST_VERIFY (func_p () == 0xbadbeef); +}