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author | 2015-01-21 01:51:10 -0500 | |
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committer | 2015-01-21 01:51:10 -0500 | |
commit | ccdb048df457d581f6ac7ede8b0c7a593a891dfa (patch) | |
tree | 9f87447c45093fb2ded95c982e68c9e6e886129c /dlfcn | |
parent | Fix semaphore destruction (bug 12674). (diff) | |
download | glibc-ccdb048df457d581f6ac7ede8b0c7a593a891dfa.tar.gz glibc-ccdb048df457d581f6ac7ede8b0c7a593a891dfa.tar.bz2 glibc-ccdb048df457d581f6ac7ede8b0c7a593a891dfa.zip |
Fix recursive dlopen.
The ability to recursively call dlopen is useful for malloc
implementations that wish to load other dynamic modules that
implement reentrant/AS-safe functions to use in their own
implementation.
Given that a user malloc implementation may be called by an
ongoing dlopen to allocate memory the user malloc
implementation interrupts dlopen and if it calls dlopen again
that's a reentrant call.
This patch fixes the issues with the ld.so.cache mapping
and the _r_debug assertion which prevent this from working
as expected.
See:
https://sourceware.org/ml/libc-alpha/2014-12/msg00446.html
Diffstat (limited to 'dlfcn')
-rw-r--r-- | dlfcn/Makefile | 7 | ||||
-rw-r--r-- | dlfcn/moddummy1.c | 10 | ||||
-rw-r--r-- | dlfcn/moddummy2.c | 13 | ||||
-rw-r--r-- | dlfcn/tst-rec-dlopen.c | 144 |
4 files changed, 172 insertions, 2 deletions
diff --git a/dlfcn/Makefile b/dlfcn/Makefile index fce4aaeb08..363278aced 100644 --- a/dlfcn/Makefile +++ b/dlfcn/Makefile @@ -36,13 +36,13 @@ endif ifeq (yes,$(build-shared)) tests = glrefmain failtest tst-dladdr default errmsg1 tstcxaatexit \ bug-dlopen1 bug-dlsym1 tst-dlinfo bug-atexit1 bug-atexit2 \ - bug-atexit3 tstatexit bug-dl-leaf + bug-atexit3 tstatexit bug-dl-leaf tst-rec-dlopen endif modules-names = glreflib1 glreflib2 glreflib3 failtestmod defaultmod1 \ defaultmod2 errmsg1mod modatexit modcxaatexit \ bug-dlsym1-lib1 bug-dlsym1-lib2 bug-atexit1-lib \ bug-atexit2-lib bug-atexit3-lib bug-dl-leaf-lib \ - bug-dl-leaf-lib-cb + bug-dl-leaf-lib-cb moddummy1 moddummy2 failtestmod.so-no-z-defs = yes glreflib2.so-no-z-defs = yes @@ -139,3 +139,6 @@ $(objpfx)bug-dl-leaf: $(objpfx)bug-dl-leaf-lib.so $(objpfx)bug-dl-leaf.out: $(objpfx)bug-dl-leaf-lib-cb.so $(objpfx)bug-dl-leaf-lib.so: $(libdl) $(objpfx)bug-dl-leaf-lib-cb.so: $(objpfx)bug-dl-leaf-lib.so + +$(objpfx)tst-rec-dlopen: $(libdl) +$(objpfx)tst-rec-dlopen.out: $(objpfx)moddummy1.so $(objpfx)moddummy2.so diff --git a/dlfcn/moddummy1.c b/dlfcn/moddummy1.c new file mode 100644 index 0000000000..6e549fa7d2 --- /dev/null +++ b/dlfcn/moddummy1.c @@ -0,0 +1,10 @@ +/* Provide a dummy DSO for tst-rec-dlopen to use. */ +#include <stdio.h> +#include <stdlib.h> + +int +dummy1 (void) +{ + printf ("Called dummy1()\n"); + return 1; +} diff --git a/dlfcn/moddummy2.c b/dlfcn/moddummy2.c new file mode 100644 index 0000000000..cb4edc8da7 --- /dev/null +++ b/dlfcn/moddummy2.c @@ -0,0 +1,13 @@ +/* Provide a dummy DSO for tst-rec-dlopen to use. */ +#include <stdio.h> +#include <stdlib.h> + +int +dummy2 (void) +{ + printf ("Called dummy2()\n"); + /* If the outer dlopen is not dummy1 (becuase of some error) + then tst-rec-dlopen will see a value of -1 as the returned + result and fail. */ + return -1; +} diff --git a/dlfcn/tst-rec-dlopen.c b/dlfcn/tst-rec-dlopen.c new file mode 100644 index 0000000000..35b08d4b63 --- /dev/null +++ b/dlfcn/tst-rec-dlopen.c @@ -0,0 +1,144 @@ +/* Test recursive dlopen using malloc hooks. + Copyright (C) 1998-2014 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Ulrich Drepper <drepper@cygnus.com>, 1998. + + 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 + <http://www.gnu.org/licenses/>. */ + +#include <stdio.h> +#include <stdlib.h> +#include <malloc.h> +#include <dlfcn.h> + +#define DSO "moddummy1.so" +#define FUNC "dummy1" + +#define DSO1 "moddummy2.so" +#define FUNC1 "dummy2" + +/* Result of the called function. */ +int func_result; + +/* Prototype for my hook. */ +void *custom_malloc_hook (size_t, const void *); + +/* Pointer to old malloc hooks. */ +void *(*old_malloc_hook) (size_t, const void *); + +/* Call function func_name in DSO dso_name via dlopen. */ +void +call_func (const char *dso_name, const char *func_name) +{ + int ret; + void *dso; + int (*func) (void); + char *err; + + /* Open the DSO. */ + dso = dlopen (dso_name, RTLD_NOW|RTLD_GLOBAL); + if (dso == NULL) + { + err = dlerror (); + fprintf (stderr, "%s\n", err); + exit (1); + } + /* Clear any errors. */ + dlerror (); + + /* Lookup func. */ + *(void **) (&func) = dlsym (dso, func_name); + if (func == NULL) + { + err = dlerror (); + if (err != NULL) + { + fprintf (stderr, "%s\n", err); + exit (1); + } + } + /* Call func. */ + func_result = (*func) (); + + /* Close the library and look for errors too. */ + ret = dlclose (dso); + if (ret != 0) + { + err = dlerror (); + fprintf (stderr, "%s\n", err); + exit (1); + } + +} + +/* Empty hook that does nothing. */ +void * +custom_malloc_hook (size_t size, const void *caller) +{ + void *result; + /* Restore old hooks. */ + __malloc_hook = old_malloc_hook; + /* First call a function in another library via dlopen. */ + call_func (DSO1, FUNC1); + /* Called recursively. */ + result = malloc (size); + /* Restore new hooks. */ + __malloc_hook = custom_malloc_hook; + return result; +} + +static int +do_test (void) +{ + /* Save old hook. */ + old_malloc_hook = __malloc_hook; + /* Install new hook. */ + __malloc_hook = custom_malloc_hook; + + /* Bug 17702 fixes two things: + * A recursive dlopen unmapping the ld.so.cache. + * An assertion that _r_debug is RT_CONSISTENT at entry to dlopen. + We can only test the latter. Testing the former requires modifying + ld.so.conf to cache the dummy libraries, then running ldconfig, + then run the test. If you do all of that (and glibc's test + infrastructure doesn't support that yet) then the test will + SEGFAULT without the fix. If you don't do that, then the test + will abort because of the assert described in detail below. */ + call_func (DSO, FUNC); + + /* Restore old hook. */ + __malloc_hook = old_malloc_hook; + + /* The function dummy2() is called by the malloc hook. Check to + see that it was called. This ensures the second recursive + dlopen happened and we called the function in that library. + Before the fix you either get a SIGSEGV when accessing mmap'd + ld.so.cache data or an assertion failure about _r_debug not + beint RT_CONSISTENT. We don't test for the SIGSEGV since it + would require finding moddummy1 or moddummy2 in the cache and + we don't have any infrastructure to test that, but the _r_debug + assertion triggers. */ + printf ("Returned result is %d\n", func_result); + if (func_result <= 0) + { + printf ("FAIL: Function call_func() not called.\n"); + exit (1); + } + + printf ("PASS: Function call_func() called more than once.\n"); + return 0; +} + +#define TEST_FUNCTION do_test () +#include "../test-skeleton.c" |