From ed421fca42fd9b4cab7c66e77894b8dd7ca57ed0 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Tue, 11 Jul 2017 07:44:01 -0700 Subject: [PATCH] Avoid backtrace from __stack_chk_fail [BZ #12189] __stack_chk_fail is called on corrupted stack. Stack backtrace is very unreliable against corrupted stack. __libc_message is changed to accept enum __libc_message_action and call BEFORE_ABORT only if action includes do_backtrace. __fortify_fail_abort is added to avoid backtrace from __stack_chk_fail. [BZ #12189] * debug/Makefile (CFLAGS-tst-ssp-1.c): New. (tests): Add tst-ssp-1 if -fstack-protector works. * debug/fortify_fail.c: Include . (_fortify_fail_abort): New function. (__fortify_fail): Call _fortify_fail_abort. (__fortify_fail_abort): Add a hidden definition. * debug/stack_chk_fail.c: Include . (__stack_chk_fail): Call __fortify_fail_abort, instead of __fortify_fail. * debug/tst-ssp-1.c: New file. * include/stdio.h (__libc_message_action): New enum. (__libc_message): Replace int with enum __libc_message_action. (__fortify_fail_abort): New hidden prototype. * malloc/malloc.c (malloc_printerr): Update __libc_message calls. * sysdeps/posix/libc_fatal.c (__libc_message): Replace int with enum __libc_message_action. Call BEFORE_ABORT only if action includes do_backtrace. (__libc_fatal): Update __libc_message call. --- ChangeLog | 22 +++++++++++++++++++ debug/Makefile | 6 +++++ debug/fortify_fail.c | 15 +++++++++++-- debug/stack_chk_fail.c | 3 ++- debug/tst-ssp-1.c | 45 ++++++++++++++++++++++++++++++++++++++ include/stdio.h | 13 ++++++++++- malloc/malloc.c | 6 +++-- sysdeps/posix/libc_fatal.c | 11 +++++----- 8 files changed, 110 insertions(+), 11 deletions(-) create mode 100644 debug/tst-ssp-1.c diff --git a/ChangeLog b/ChangeLog index 7ee4f2d686..081551fdce 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,25 @@ +2017-07-11 H.J. Lu + + [BZ #12189] + * debug/Makefile (CFLAGS-tst-ssp-1.c): New. + (tests): Add tst-ssp-1 if -fstack-protector works. + * debug/fortify_fail.c: Include . + (_fortify_fail_abort): New function. + (__fortify_fail): Call _fortify_fail_abort. + (__fortify_fail_abort): Add a hidden definition. + * debug/stack_chk_fail.c: Include . + (__stack_chk_fail): Call __fortify_fail_abort, instead of + __fortify_fail. + * debug/tst-ssp-1.c: New file. + * include/stdio.h (__libc_message_action): New enum. + (__libc_message): Replace int with enum __libc_message_action. + (__fortify_fail_abort): New hidden prototype. + * malloc/malloc.c (malloc_printerr): Update __libc_message calls. + * sysdeps/posix/libc_fatal.c (__libc_message): Replace int + with enum __libc_message_action. Call BEFORE_ABORT only if + action includes do_backtrace. + (__libc_fatal): Update __libc_message call. + 2017-07-11 Adhemerval Zanella [BZ #21738] diff --git a/debug/Makefile b/debug/Makefile index cd4975c35b..c6d78727f0 100644 --- a/debug/Makefile +++ b/debug/Makefile @@ -139,12 +139,18 @@ LDFLAGS-tst-backtrace4 = -rdynamic LDFLAGS-tst-backtrace5 = -rdynamic LDFLAGS-tst-backtrace6 = -rdynamic +CFLAGS-tst-ssp-1.c = -fstack-protector + tests = backtrace-tst tst-longjmp_chk tst-chk1 tst-chk2 tst-chk3 \ tst-lfschk1 tst-lfschk2 tst-lfschk3 test-strcpy_chk test-stpcpy_chk \ tst-chk4 tst-chk5 tst-chk6 tst-lfschk4 tst-lfschk5 tst-lfschk6 \ tst-longjmp_chk2 tst-backtrace2 tst-backtrace3 tst-backtrace4 \ tst-backtrace5 tst-backtrace6 +ifeq ($(have-ssp),yes) +tests += tst-ssp-1 +endif + ifeq (,$(CXX)) tests-unsupported = tst-chk4 tst-chk5 tst-chk6 \ tst-lfschk4 tst-lfschk5 tst-lfschk6 diff --git a/debug/fortify_fail.c b/debug/fortify_fail.c index a31977a40f..c90d384daf 100644 --- a/debug/fortify_fail.c +++ b/debug/fortify_fail.c @@ -17,17 +17,28 @@ #include #include +#include extern char **__libc_argv attribute_hidden; void __attribute__ ((noreturn)) internal_function -__fortify_fail (const char *msg) +__fortify_fail_abort (_Bool do_backtrace, const char *msg) { /* The loop is added only to keep gcc happy. */ while (1) - __libc_message (2, "*** %s ***: %s terminated\n", + __libc_message (do_backtrace ? (do_abort | do_backtrace) : do_abort, + "*** %s ***: %s terminated\n", msg, __libc_argv[0] ?: ""); } + +void +__attribute__ ((noreturn)) internal_function +__fortify_fail (const char *msg) +{ + __fortify_fail_abort (true, msg); +} + libc_hidden_def (__fortify_fail) +libc_hidden_def (__fortify_fail_abort) diff --git a/debug/stack_chk_fail.c b/debug/stack_chk_fail.c index 4f7346481d..9ab9bc7ceb 100644 --- a/debug/stack_chk_fail.c +++ b/debug/stack_chk_fail.c @@ -17,6 +17,7 @@ #include #include +#include extern char **__libc_argv attribute_hidden; @@ -25,7 +26,7 @@ void __attribute__ ((noreturn)) __stack_chk_fail (void) { - __fortify_fail ("stack smashing detected"); + __fortify_fail_abort (false, "stack smashing detected"); } strong_alias (__stack_chk_fail, __stack_chk_fail_local) diff --git a/debug/tst-ssp-1.c b/debug/tst-ssp-1.c new file mode 100644 index 0000000000..52c67e2c92 --- /dev/null +++ b/debug/tst-ssp-1.c @@ -0,0 +1,45 @@ +/* Verify that __stack_chk_fail won't segfault. + Copyright (C) 2017 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 + . */ + +/* Based on gcc.dg/ssp-1.c from GCC testsuite. */ + +#include + +static void +__attribute__ ((noinline, noclone)) +test (char *foo) +{ + int i; + + /* smash stack */ + for (i = 0; i <= 400; i++) + foo[i] = 42; +} + +static int +do_test (void) +{ + char foo[30]; + + test (foo); + + return 1; /* fail */ +} + +#define EXPECTED_SIGNAL SIGABRT +#include diff --git a/include/stdio.h b/include/stdio.h index f68f633bd6..215f919990 100644 --- a/include/stdio.h +++ b/include/stdio.h @@ -86,13 +86,24 @@ extern int __gen_tempname (char *__tmpl, int __suffixlen, int __flags, # define __GT_DIR 1 /* create a directory */ # define __GT_NOCREATE 2 /* just find a name not currently in use */ +enum __libc_message_action +{ + do_message = 0, /* Print message. */ + do_abort = 1 << 0, /* Abort. */ + do_backtrace = 1 << 1 /* Backtrace. */ +}; + /* Print out MESSAGE on the error output and abort. */ extern void __libc_fatal (const char *__message) __attribute__ ((__noreturn__)); -extern void __libc_message (int do_abort, const char *__fnt, ...); +extern void __libc_message (enum __libc_message_action action, + const char *__fnt, ...); extern void __fortify_fail (const char *msg) __attribute__ ((__noreturn__)) internal_function; +extern void __fortify_fail_abort (_Bool, const char *msg) + __attribute__ ((__noreturn__)) internal_function; libc_hidden_proto (__fortify_fail) +libc_hidden_proto (__fortify_fail_abort) /* Acquire ownership of STREAM. */ extern void __flockfile (FILE *__stream); diff --git a/malloc/malloc.c b/malloc/malloc.c index 2527e25047..54e406bcb6 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -5397,7 +5397,8 @@ malloc_printerr (int action, const char *str, void *ptr, mstate ar_ptr) set_arena_corrupt (ar_ptr); if ((action & 5) == 5) - __libc_message (action & 2, "%s\n", str); + __libc_message ((action & 2) ? (do_abort | do_backtrace) : do_message, + "%s\n", str); else if (action & 1) { char buf[2 * sizeof (uintptr_t) + 1]; @@ -5407,7 +5408,8 @@ malloc_printerr (int action, const char *str, void *ptr, mstate ar_ptr) while (cp > buf) *--cp = '0'; - __libc_message (action & 2, "*** Error in `%s': %s: 0x%s ***\n", + __libc_message ((action & 2) ? (do_abort | do_backtrace) : do_message, + "*** Error in `%s': %s: 0x%s ***\n", __libc_argv[0] ? : "", str, cp); } else if (action & 2) diff --git a/sysdeps/posix/libc_fatal.c b/sysdeps/posix/libc_fatal.c index b261963679..25af8bd413 100644 --- a/sysdeps/posix/libc_fatal.c +++ b/sysdeps/posix/libc_fatal.c @@ -64,7 +64,7 @@ struct str_list /* Abort with an error message. */ void -__libc_message (int do_abort, const char *fmt, ...) +__libc_message (enum __libc_message_action action, const char *fmt, ...) { va_list ap; int fd = -1; @@ -140,7 +140,7 @@ __libc_message (int do_abort, const char *fmt, ...) written = WRITEV_FOR_FATAL (fd, iov, nlist, total); - if (do_abort) + if ((action & do_abort)) { total = ((total + 1 + GLRO(dl_pagesize) - 1) & ~(GLRO(dl_pagesize) - 1)); @@ -167,9 +167,10 @@ __libc_message (int do_abort, const char *fmt, ...) va_end (ap); - if (do_abort) + if ((action & do_abort)) { - BEFORE_ABORT (do_abort, written, fd); + if ((action & do_backtrace)) + BEFORE_ABORT (do_abort, written, fd); /* Kill the application. */ abort (); @@ -182,6 +183,6 @@ __libc_fatal (const char *message) { /* The loop is added only to keep gcc happy. */ while (1) - __libc_message (1, "%s", message); + __libc_message (do_abort | do_backtrace, "%s", message); } libc_hidden_def (__libc_fatal) -- 2.43.5