From 6029860f6fb465ac35c68c71e3899b9b872b6b26 Mon Sep 17 00:00:00 2001 From: Florian Weimer Date: Fri, 29 Nov 2019 16:37:58 +0100 Subject: [PATCH] elf: Do not run IFUNC resolvers for LD_DEBUG=unused [BZ #24214] This commit adds missing skip_ifunc checks to aarch64, arm, i386, sparc, and x86_64. A new test case ensures that IRELATIVE IFUNC resolvers do not run in various diagnostic modes of the dynamic loader. Tested on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, s390-linux-gnu, s390x-linux-gnu, powerpc64le-linux-gnu. Built with build-many-glibcs.py. --- elf/Makefile | 16 +++++++++ elf/tst-ifunc-fault-bindnow.c | 21 +++++++++++ elf/tst-ifunc-fault-lazy.c | 57 ++++++++++++++++++++++++++++++ sysdeps/aarch64/dl-machine.h | 3 +- sysdeps/arm/dl-machine.h | 6 ++-- sysdeps/i386/dl-machine.h | 6 ++-- sysdeps/sparc/sparc32/dl-machine.h | 6 ++-- sysdeps/sparc/sparc64/dl-machine.h | 6 ++-- sysdeps/x86_64/dl-machine.h | 3 +- 9 files changed, 114 insertions(+), 10 deletions(-) create mode 100644 elf/tst-ifunc-fault-bindnow.c create mode 100644 elf/tst-ifunc-fault-lazy.c diff --git a/elf/Makefile b/elf/Makefile index 305bed2d38..f825354d3f 100644 --- a/elf/Makefile +++ b/elf/Makefile @@ -348,6 +348,7 @@ tests-ifuncstatic := ifuncmain1static ifuncmain1picstatic \ tests-static += $(tests-ifuncstatic) tests-internal += $(tests-ifuncstatic) ifeq (yes,$(build-shared)) +tests += tst-ifunc-fault-lazy tst-ifunc-fault-bindnow # Note: sysdeps/x86_64/ifuncmain8.c uses ifuncmain8. tests-internal += \ ifuncmain1 ifuncmain1pic ifuncmain1vis ifuncmain1vispic \ @@ -1354,6 +1355,21 @@ $(objpfx)ifuncmain5static: $(addprefix $(objpfx),ifuncdep5.o) $(objpfx)ifuncmain5staticpic: $(addprefix $(objpfx),ifuncdep5pic.o) $(objpfx)ifuncmain5picstatic: $(addprefix $(objpfx),ifuncdep5pic.o) +LDFLAGS-tst-ifunc-fault-lazy = -Wl,-z,lazy +LDFLAGS-tst-ifunc-fault-bindnow = -Wl,-z,now +define tst-ifunc-fault-script +( $(objpfx)ld.so --verify --library-path $(objpfx) $^ \ + && LD_TRACE_LOADED_OBJECTS=1 $(objpfx)ld.so --library-path $(objpfx) $^ \ + && LD_TRACE_LOADED_OBJECTS=1 LD_DEBUG=unused \ + $(objpfx)ld.so --library-path $(objpfx) $^ \ +) > $@; $(evaluate-test) +endef +$(objpfx)tst-ifunc-fault-lazy.out: $(objpfx)tst-ifunc-fault-lazy $(objpfx)ld.so + $(tst-ifunc-fault-script) +$(objpfx)tst-ifunc-fault-bindnow.out: $(objpfx)tst-ifunc-fault-bindnow \ + $(objpfx)ld.so + $(tst-ifunc-fault-script) + $(objpfx)tst-unique1: $(libdl) $(objpfx)tst-unique1.out: $(objpfx)tst-unique1mod1.so \ $(objpfx)tst-unique1mod2.so diff --git a/elf/tst-ifunc-fault-bindnow.c b/elf/tst-ifunc-fault-bindnow.c new file mode 100644 index 0000000000..d767c1f1c1 --- /dev/null +++ b/elf/tst-ifunc-fault-bindnow.c @@ -0,0 +1,21 @@ +/* Program with local IFUNC resolver which crashes. BIND_NOW variant. + Copyright (C) 2019 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 + . */ + +/* The code is the same as the lazy variant. It is just linked + differently. */ +#include "tst-ifunc-fault-lazy.c" diff --git a/elf/tst-ifunc-fault-lazy.c b/elf/tst-ifunc-fault-lazy.c new file mode 100644 index 0000000000..3389de273f --- /dev/null +++ b/elf/tst-ifunc-fault-lazy.c @@ -0,0 +1,57 @@ +/* Program with local IFUNC resolver which crashes, for testing bug 24214. + Copyright (C) 2019 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 + . */ + +/* The construct below is expected to produce an IRELATIVE relocation + with an IFUNC resolver that crashes. ldd should not performs such + relocations. */ + +#include + +#ifdef HAVE_GCC_IFUNC + +# include + +static void +implementation (void) +{ + /* Produce a crash, without depending on any relocations. */ + volatile char *volatile p = NULL; + *p = 0; +} + +static __typeof__ (implementation) * +resolver (void) +{ + /* Produce a crash, without depending on any relocations. */ + volatile char *volatile p = NULL; + *p = 0; + return implementation; +} + +static void magic (void) __attribute__ ((ifunc ("resolver"))); + +void (*magic_ptr) (void) = magic; + +#endif /* HAVE_GCC_IFUNC */ + +/* The program is expected not to run. */ +int +main (void) +{ + return 1; +} diff --git a/sysdeps/aarch64/dl-machine.h b/sysdeps/aarch64/dl-machine.h index 10b91c33ae..bf6b9d0e7d 100644 --- a/sysdeps/aarch64/dl-machine.h +++ b/sysdeps/aarch64/dl-machine.h @@ -358,7 +358,8 @@ elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc, case AARCH64_R(IRELATIVE): value = map->l_addr + reloc->r_addend; - value = elf_ifunc_invoke (value); + if (__glibc_likely (!skip_ifunc)) + value = elf_ifunc_invoke (value); *reloc_addr = value; break; diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h index eeb3adfff2..27dffc71bf 100644 --- a/sysdeps/arm/dl-machine.h +++ b/sysdeps/arm/dl-machine.h @@ -522,7 +522,8 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc, break; case R_ARM_IRELATIVE: value = map->l_addr + *reloc_addr; - value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap)); + if (__glibc_likely (!skip_ifunc)) + value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap)); *reloc_addr = value; break; #endif @@ -614,7 +615,8 @@ elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc, break; case R_ARM_IRELATIVE: value = map->l_addr + reloc->r_addend; - value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap)); + if (__glibc_likely (!skip_ifunc)) + value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap)); *reloc_addr = value; break; #endif diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h index 1e2a3b333d..e225aa3739 100644 --- a/sysdeps/i386/dl-machine.h +++ b/sysdeps/i386/dl-machine.h @@ -480,7 +480,8 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc, break; case R_386_IRELATIVE: value = map->l_addr + *reloc_addr; - value = ((Elf32_Addr (*) (void)) value) (); + if (__glibc_likely (!skip_ifunc)) + value = ((Elf32_Addr (*) (void)) value) (); *reloc_addr = value; break; default: @@ -627,7 +628,8 @@ elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc, # endif /* !RESOLVE_CONFLICT_FIND_MAP */ case R_386_IRELATIVE: value = map->l_addr + reloc->r_addend; - value = ((Elf32_Addr (*) (void)) value) (); + if (__glibc_likely (!skip_ifunc)) + value = ((Elf32_Addr (*) (void)) value) (); *reloc_addr = value; break; default: diff --git a/sysdeps/sparc/sparc32/dl-machine.h b/sysdeps/sparc/sparc32/dl-machine.h index 1d8da32c47..359a004271 100644 --- a/sysdeps/sparc/sparc32/dl-machine.h +++ b/sysdeps/sparc/sparc32/dl-machine.h @@ -425,11 +425,13 @@ elf_machine_rela (struct link_map *map, const Elf32_Rela *reloc, *reloc_addr = value; break; case R_SPARC_IRELATIVE: - value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap)); + if (__glibc_likely (!skip_ifunc)) + value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap)); *reloc_addr = value; break; case R_SPARC_JMP_IREL: - value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap)); + if (__glibc_likely (!skip_ifunc)) + value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap)); /* Fall thru */ case R_SPARC_JMP_SLOT: { diff --git a/sysdeps/sparc/sparc64/dl-machine.h b/sysdeps/sparc/sparc64/dl-machine.h index ce1261d2a0..0acaf92a53 100644 --- a/sysdeps/sparc/sparc64/dl-machine.h +++ b/sysdeps/sparc/sparc64/dl-machine.h @@ -450,11 +450,13 @@ elf_machine_rela (struct link_map *map, const Elf64_Rela *reloc, *reloc_addr = value; break; case R_SPARC_IRELATIVE: - value = ((Elf64_Addr (*) (int)) value) (GLRO(dl_hwcap)); + if (__glibc_likely (!skip_ifunc)) + value = ((Elf64_Addr (*) (int)) value) (GLRO(dl_hwcap)); *reloc_addr = value; break; case R_SPARC_JMP_IREL: - value = ((Elf64_Addr (*) (int)) value) (GLRO(dl_hwcap)); + if (__glibc_likely (!skip_ifunc)) + value = ((Elf64_Addr (*) (int)) value) (GLRO(dl_hwcap)); /* 'high' is always zero, for large PLT entries the linker emits an R_SPARC_IRELATIVE. */ #ifdef RESOLVE_CONFLICT_FIND_MAP diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h index f17f5fb7cd..58260c7876 100644 --- a/sysdeps/x86_64/dl-machine.h +++ b/sysdeps/x86_64/dl-machine.h @@ -512,7 +512,8 @@ elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc, # endif case R_X86_64_IRELATIVE: value = map->l_addr + reloc->r_addend; - value = ((ElfW(Addr) (*) (void)) value) (); + if (__glibc_likely (!skip_ifunc)) + value = ((ElfW(Addr) (*) (void)) value) (); *reloc_addr = value; break; default: