diff options
Diffstat (limited to 'elf')
| -rw-r--r-- | elf/dl-open.c | 154 |
1 files changed, 106 insertions, 48 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)) { |