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On Wed, May 16, 2001 at 10:48:21PM -0700, Ulrich Drepper wrote: > Jakub Jelinek <jakub@redhat.com> writes: > > > Ok, here are two variants of the patch. > > Finally managed to look at the patches... and don't like them. Code like > > > + if (! _dl_loaded > + || _dl_loaded->l_addr != 0 > + || caller < _dl_loaded->l_map_start) > > > makes certain assumptions about the memory layout and load addresses. > This should not happen. There is no reason why the application code > should always be below all dynamically loaded code. In fact, isn't > the x86 emulation on IA-64 doing something funny like this? How about this? Passed glibc bootstrap and make check. I couldn't find any code which would rely on l_map_end of main program being set to ~0 and it does not cost that much to initialize it properly. Further, the l->l_addr != 0 checks might work now but with prelinking they don't work at all (l_addr == 0 is then the common desirable case). In dl-open.c the comment close to the l_addr != 0 check said: Make sure we do not currently set this map up in this moment. but this test happens at the start of dl_open_worker, so this dlopen has not created any new maps yet and as it is protected with the _dl_load_lock, there cannot be anyone else creating/removing maps at the same time and all maps should be thus set up properly before dl_open_worker starts. 2001-05-21 Jakub Jelinek <jakub@redhat.com> * elf/rtld.c (dl_main): Compute l_map_end for the main program. * elf/dlsym.c (_dl_sym): Don't check for l_addr == 0. If match == _dl_loaded, caller can still come from the main program. (_dl_vsym): Likewise. * elf/dl-open.c (dl_open_worker): Don't check for l_addr == 0. * elf/dl-error.c (_dl_signal_error): Change NULL objname into "". * elf/restest2.c: New test. * elf/Makefile (tests): Add restest2. (restest2, LDFLAGS-restest2): Add. --- libc/elf/rtld.c.jj Mon May 21 11:36:03 2001 +++ libc/elf/rtld.c Mon May 21 11:42:24 2001 @@ -542,8 +542,7 @@ of this helper program; chances are you information for the program. */ } - /* It is not safe to load stuff after the main program. */ - _dl_loaded->l_map_end = ~0; + _dl_loaded->l_map_end = 0; /* Perhaps the executable has no PT_LOAD header entries at all. */ _dl_loaded->l_map_start = ~0; @@ -593,13 +592,18 @@ of this helper program; chances are you case PT_LOAD: /* Remember where the main program starts in memory. */ { - ElfW(Addr) mapstart; + ElfW(Addr) mapstart, allocend; mapstart = _dl_loaded->l_addr + (ph->p_vaddr & ~(ph->p_align - 1)); + allocend = _dl_loaded->l_addr + ph->p_vaddr + ph->p_memsz; if (_dl_loaded->l_map_start > mapstart) _dl_loaded->l_map_start = mapstart; + if (_dl_loaded->l_map_end < allocend) + _dl_loaded->l_map_end = allocend; } break; } + if (! _dl_loaded->l_map_end) + _dl_loaded->l_map_end = ~0; if (! _dl_rtld_map.l_libname && _dl_rtld_map.l_name) { /* We were invoked directly, so the program might not have a --- libc/elf/dl-sym.c.jj Mon May 21 11:36:03 2001 +++ libc/elf/dl-sym.c Mon May 21 11:42:24 2001 @@ -41,7 +41,7 @@ _dl_sym (void *handle, const char *name, /* Find the highest-addressed object that CALLER is not below. */ for (l = _dl_loaded; l != NULL; l = l->l_next) - if (l->l_addr != 0 && caller >= l->l_map_start && caller < l->l_map_end) + if (caller >= l->l_map_start && caller < l->l_map_end) { /* There must be exactly one DSO for the range of the virtual memory. Otherwise something is really broken. */ @@ -65,8 +65,13 @@ _dl_sym (void *handle, const char *name, else { if (__builtin_expect (match == _dl_loaded, 0)) - _dl_signal_error (0, NULL, N_("\ + { + if (! _dl_loaded + || caller < _dl_loaded->l_map_start + || caller >= _dl_loaded->l_map_end) + _dl_signal_error (0, NULL, N_("\ RTLD_NEXT used in code not dynamically loaded")); + } l = match; while (l->l_loader != NULL) @@ -107,7 +112,7 @@ _dl_vsym (void *handle, const char *name /* Find the highest-addressed object that CALLER is not below. */ for (l = _dl_loaded; l != NULL; l = l->l_next) - if (l->l_addr != 0 && caller >= l->l_map_start && caller < l->l_map_end) + if (caller >= l->l_map_start && caller < l->l_map_end) { /* There must be exactly one DSO for the range of the virtual memory. Otherwise something is really broken. */ @@ -121,9 +126,14 @@ _dl_vsym (void *handle, const char *name &vers, 0, 0); else if (handle == RTLD_NEXT) { - if (match == _dl_loaded) - _dl_signal_error (0, NULL, N_("\ + if (__builtin_expect (match == _dl_loaded, 0)) + { + if (! _dl_loaded + || caller < _dl_loaded->l_map_start + || caller >= _dl_loaded->l_map_end) + _dl_signal_error (0, NULL, N_("\ RTLD_NEXT used in code not dynamically loaded")); + } l = match; while (l->l_loader != NULL) --- libc/elf/dl-open.c.jj Mon May 21 11:36:02 2001 +++ libc/elf/dl-open.c Mon May 21 11:42:24 2001 @@ -188,13 +188,10 @@ dl_open_worker (void *a) _dl_signal_error (0, "dlopen", N_("DST not allowed in SUID/SGID programs")); - /* We have to find out from which object the caller is calling. - Find the highest-addressed object that ADDRESS is not below. */ + /* We have to find out from which object the caller is calling. */ call_map = NULL; for (l = _dl_loaded; l; l = l->l_next) - if (l->l_addr != 0 /* Make sure we do not currently set this map up - in this moment. */ - && caller >= (const void *) l->l_map_start + if (caller >= (const void *) l->l_map_start && caller < (const void *) l->l_map_end) { /* There must be exactly one DSO for the range of the virtual --- libc/elf/dl-error.c.jj Mon May 21 11:43:57 2001 +++ libc/elf/dl-error.c Mon May 21 11:44:06 2001 @@ -71,6 +71,8 @@ _dl_signal_error (int errcode, const cha errstring = N_("DYNAMIC LINKER BUG!!!"); lcatch = tsd_getspecific (); + if (objname == NULL) + objname = ""; if (lcatch != NULL) { /* We are inside _dl_catch_error. Return to it. We have to @@ -100,7 +102,7 @@ _dl_signal_error (int errcode, const cha _dl_fatal_printf ("\ %s: error while loading shared libraries: %s%s%s%s%s\n", _dl_argv[0] ?: "<program name unknown>", - objname ?: "", objname && *objname ? ": " : "", + objname, *objname ? ": " : "", errstring, errcode ? ": " : "", (errcode ? __strerror_r (errcode, buffer, sizeof buffer) --- libc/elf/restest2.c.jj Mon May 21 11:44:06 2001 +++ libc/elf/restest2.c Mon May 21 11:44:06 2001 @@ -0,0 +1,33 @@ +#include <sys/types.h> +#include <dlfcn.h> +#include <error.h> +#include <mcheck.h> +#include <stdlib.h> +#include <unistd.h> + +pid_t pid, pid2; + +pid_t getpid(void) +{ + pid_t (*f)(void); + f = (pid_t (*)(void)) dlsym (RTLD_NEXT, "getpid"); + if (f == NULL) + error (EXIT_FAILURE, 0, "dlsym (RTLD_NEXT, \"getpid\"): %s", dlerror ()); + return (pid2 = f()) + 26; +} + +int +main (void) +{ + pid_t (*f)(void); + + mtrace (); + + f = (pid_t (*)(void)) dlsym (RTLD_DEFAULT, "getpid"); + if (f == NULL) + error (EXIT_FAILURE, 0, "dlsym (RTLD_DEFAULT, \"getpid\"): %s", dlerror ()); + pid = f(); + if (pid != pid2 + 26) + error (EXIT_FAILURE, 0, "main getpid() not called"); + return 0; +} --- libc/elf/Makefile.jj Mon May 21 11:43:57 2001 +++ libc/elf/Makefile Mon May 21 11:44:06 2001 @@ -101,7 +101,8 @@ tests = loadtest restest1 preloadtest lo constload1 order $(tests-vis-$(have-protected)) noload filter unload \ reldep reldep2 reldep3 next $(tests-nodelete-$(have-z-nodelete)) \ $(tests-nodlopen-$(have-z-nodlopen)) neededtest neededtest2 \ - neededtest3 neededtest4 unload2 lateglobal initfirst global + neededtest3 neededtest4 unload2 lateglobal initfirst global \ + restest2 test-srcs = tst-pathopt tests-vis-yes = vismain tests-nodelete-yes = nodelete @@ -302,6 +303,9 @@ $(objpfx)neededtest4.out: $(objpfx)neede $(objpfx)restest1: $(objpfx)testobj1.so $(objpfx)testobj1_1.so $(libdl) LDFLAGS-restest1 = -rdynamic + +$(objpfx)restest2: $(libdl) +LDFLAGS-restest2 = -rdynamic $(objpfx)restest1.out: $(test-modules) Jakub
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