diff options
| -rw-r--r-- | elf/dl-open.c | 154 | ||||
| -rw-r--r-- | sysdeps/generic/ldsodefs.h | 9 |
2 files changed, 114 insertions, 49 deletions
diff --git a/elf/dl-open.c b/elf/dl-open.c index 533fb96..bedbd3a 100644 --- a/elf/dl-open.c +++ b/elf/dl-open.c @@ -50,22 +50,38 @@ struct dl_open_args struct link_map *map; /* Namespace ID. */ Lmid_t nsid; + + /* Original value of _ns_global_scope_pending_adds. Set by + dl_open_worker. Only valid if nsid is a real namespace + (non-negative). */ + unsigned int original_global_scope_pending_adds; + /* Original parameters to the program and the current environment. */ int argc; char **argv; char **env; }; +/* Called in case the global scope cannot be extended. */ +static void __attribute__ ((noreturn)) +add_to_global_resize_failure (struct link_map *new) +{ + _dl_signal_error (ENOMEM, new->l_libname->name, NULL, + N_ ("cannot extend global scope")); +} -static int -add_to_global (struct link_map *new) +/* Grow the global scope array for the namespace, so that all the new + global objects can be added later in add_to_global_update, without + risk of memory allocation failure. add_to_global_resize raises + exceptions for memory allocation errors. */ +static void +add_to_global_resize (struct link_map *new) { - struct link_map **new_global; - unsigned int to_add = 0; - unsigned int cnt; + struct link_namespaces *ns = &GL (dl_ns)[new->l_ns]; /* Count the objects we have to put in the global scope. */ - for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt) + unsigned int to_add = 0; + for (unsigned int cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt) if (new->l_searchlist.r_list[cnt]->l_global == 0) ++to_add; @@ -83,47 +99,51 @@ add_to_global (struct link_map *new) in an realloc() call. Therefore we allocate a completely new array the first time we have to add something to the locale scope. */ - struct link_namespaces *ns = &GL(dl_ns)[new->l_ns]; + if (__builtin_add_overflow (ns->_ns_global_scope_pending_adds, to_add, + &ns->_ns_global_scope_pending_adds)) + add_to_global_resize_failure (new); + + unsigned int new_size = 0; /* 0 means no new allocation. */ + void *old_global = NULL; /* Old allocation if free-able. */ + + /* Minimum required element count for resizing. Adjusted below for + an exponential resizing policy. */ + size_t required_new_size; + if (__builtin_add_overflow (ns->_ns_main_searchlist->r_nlist, + ns->_ns_global_scope_pending_adds, + &required_new_size)) + add_to_global_resize_failure (new); + if (ns->_ns_global_scope_alloc == 0) { - /* This is the first dynamic object given global scope. */ - ns->_ns_global_scope_alloc - = ns->_ns_main_searchlist->r_nlist + to_add + 8; - new_global = (struct link_map **) - malloc (ns->_ns_global_scope_alloc * sizeof (struct link_map *)); - if (new_global == NULL) - { - ns->_ns_global_scope_alloc = 0; - nomem: - _dl_signal_error (ENOMEM, new->l_libname->name, NULL, - N_("cannot extend global scope")); - return 1; - } + if (__builtin_add_overflow (required_new_size, 8, &new_size)) + add_to_global_resize_failure (new); + } + else if (required_new_size > ns->_ns_global_scope_alloc) + { + if (__builtin_mul_overflow (required_new_size, 2, &new_size)) + add_to_global_resize_failure (new); - /* Copy over the old entries. */ - ns->_ns_main_searchlist->r_list - = memcpy (new_global, ns->_ns_main_searchlist->r_list, - (ns->_ns_main_searchlist->r_nlist - * sizeof (struct link_map *))); + /* The old array was allocated with our malloc, not the minimal + malloc. */ + old_global = ns->_ns_main_searchlist->r_list; } - else if (ns->_ns_main_searchlist->r_nlist + to_add - > ns->_ns_global_scope_alloc) + + if (new_size > 0) { - /* We have to extend the existing array of link maps in the - main map. */ - struct link_map **old_global - = GL(dl_ns)[new->l_ns]._ns_main_searchlist->r_list; - size_t new_nalloc = ((ns->_ns_global_scope_alloc + to_add) * 2); - - new_global = (struct link_map **) - malloc (new_nalloc * sizeof (struct link_map *)); + size_t allocation_size; + if (__builtin_mul_overflow (new_size, sizeof (struct link_map *), + &allocation_size)) + add_to_global_resize_failure (new); + struct link_map **new_global = malloc (allocation_size); if (new_global == NULL) - goto nomem; + add_to_global_resize_failure (new); - memcpy (new_global, old_global, - ns->_ns_global_scope_alloc * sizeof (struct link_map *)); + /* Copy over the old entries. */ + memcpy (new_global, ns->_ns_main_searchlist->r_list, + ns->_ns_main_searchlist->r_nlist * sizeof (struct link_map *)); - ns->_ns_global_scope_alloc = new_nalloc; + ns->_ns_global_scope_alloc = new_size; ns->_ns_main_searchlist->r_list = new_global; if (!RTLD_SINGLE_THREAD_P) @@ -131,16 +151,28 @@ add_to_global (struct link_map *new) free (old_global); } +} + +/* Actually add the new global objects to the global scope. Must be + called after add_to_global_resize. This function cannot fail. */ +static void +add_to_global_update (struct link_map *new) +{ + struct link_namespaces *ns = &GL (dl_ns)[new->l_ns]; /* Now add the new entries. */ unsigned int new_nlist = ns->_ns_main_searchlist->r_nlist; - for (cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt) + for (unsigned int cnt = 0; cnt < new->l_searchlist.r_nlist; ++cnt) { struct link_map *map = new->l_searchlist.r_list[cnt]; if (map->l_global == 0) { map->l_global = 1; + + /* The array has been resized by add_to_global_resize. */ + assert (new_nlist < ns->_ns_global_scope_alloc); + ns->_ns_main_searchlist->r_list[new_nlist++] = map; /* We modify the global scope. Report this. */ @@ -149,10 +181,15 @@ add_to_global (struct link_map *new) map->l_name, map->l_ns); } } + + /* Some of the pending adds have been performed by the loop above. + Adjust the counter accordingly. */ + unsigned int added = new_nlist - ns->_ns_main_searchlist->r_nlist; + assert (added <= ns->_ns_global_scope_pending_adds); + ns->_ns_global_scope_pending_adds -= added; + atomic_write_barrier (); ns->_ns_main_searchlist->r_nlist = new_nlist; - - return 0; } /* Search link maps in all namespaces for the DSO that contains the object at @@ -225,6 +262,10 @@ dl_open_worker (void *a) args->nsid = call_map->l_ns; } + /* Retain the old value, so that it can be restored. */ + args->original_global_scope_pending_adds + = GL (dl_ns)[args->nsid]._ns_global_scope_pending_adds; + /* One might be tempted to assert that we are RT_CONSISTENT at this point, but that may not be true if this is a recursive call to dlopen. */ _dl_debug_initialize (0, args->nsid); @@ -266,7 +307,10 @@ dl_open_worker (void *a) /* If the user requested the object to be in the global namespace but it is not so far, add it now. */ if ((mode & RTLD_GLOBAL) && new->l_global == 0) - (void) add_to_global (new); + { + add_to_global_resize (new); + add_to_global_update (new); + } assert (_dl_debug_initialize (0, args->nsid)->r_state == RT_CONSISTENT); @@ -526,6 +570,11 @@ TLS generation counter wrapped! Please report this.")); DL_STATIC_INIT (new); #endif + /* Perform the necessary allocations for adding new global objects + to the global scope below, via add_to_global_update. */ + if (mode & RTLD_GLOBAL) + add_to_global_resize (new); + /* Run the initializer functions of new objects. Temporarily disable the exception handler, so that lazy binding failures are fatal. */ @@ -542,10 +591,7 @@ TLS generation counter wrapped! Please report this.")); /* Now we can make the new map available in the global scope. */ if (mode & RTLD_GLOBAL) - /* Move the object in the global namespace. */ - if (add_to_global (new) != 0) - /* It failed. */ - return; + add_to_global_update (new); #ifndef SHARED /* We must be the static _dl_open in libc.a. A static program that @@ -559,7 +605,6 @@ TLS generation counter wrapped! Please report this.")); new->l_name, new->l_ns, new->l_direct_opencount); } - void * _dl_open (const char *file, int mode, const void *caller_dlopen, Lmid_t nsid, int argc, char *argv[], char *env[]) @@ -627,6 +672,19 @@ no more namespaces available for dlmopen()")); _dl_unload_cache (); #endif + /* Do this for both the error and success cases. The old value has + only been determined if the namespace ID was assigned (i.e., it + is not __LM_ID_CALLER). In the success case, we actually may + have consumed more pending adds than planned (because the local + scopes overlap in case of a recursive dlopen, the inner dlopen + doing some of the globalization work of the outer dlopen), so the + old pending adds value is larger than absolutely necessary. + Since it is just a conservative upper bound, this is harmless. + The top-level dlopen call will restore the field to zero. */ + if (args.nsid >= 0) + GL (dl_ns)[args.nsid]._ns_global_scope_pending_adds + = args.original_global_scope_pending_adds; + /* See if an error occurred during loading. */ if (__glibc_unlikely (exception.errstring != NULL)) { diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h index 9737780..c0017b8 100644 --- a/sysdeps/generic/ldsodefs.h +++ b/sysdeps/generic/ldsodefs.h @@ -328,7 +328,14 @@ struct rtld_global /* This is zero at program start to signal that the global scope map is allocated by rtld. Later it keeps the size of the map. It might be reset if in _dl_close if the last global object is removed. */ - size_t _ns_global_scope_alloc; + unsigned int _ns_global_scope_alloc; + + /* During dlopen, this is the number of objects that still need to + be added to the global scope map. It has to be taken into + account when resizing the map, for future map additions after + recursive dlopen calls from ELF constructors. */ + unsigned int _ns_global_scope_pending_adds; + /* Search table for unique objects. */ struct unique_sym_table { |