From 11b451c8868d8a2b0edc5dfd44fc58d9ee538be0 Mon Sep 17 00:00:00 2001 From: Mark Wielaard Date: Wed, 15 May 2019 17:14:01 +0200 Subject: [PATCH] dlfcn: Guard __dlerror_main_freeres with __libc_once_get (once) [BZ# 24476] dlerror.c (__dlerror_main_freeres) will try to free resources which only have been initialized when init () has been called. That function is called when resources are needed using __libc_once (once, init) where once is a __libc_once_define (static, once) in the dlerror.c file. Trying to free those resources if init () hasn't been called will produce errors under valgrind memcheck. So guard the freeing of those resources using __libc_once_get (once) and make sure we have a valid key. Also add a similar guard to __dlerror (). * dlfcn/dlerror.c (__dlerror_main_freeres): Guard using __libc_once_get (once) and static_bug == NULL. (__dlerror): Check we have a valid key, set result to static_buf otherwise. Reviewed-by: Carlos O'Donell --- ChangeLog | 8 ++++++++ dlfcn/dlerror.c | 29 +++++++++++++++++++++-------- 2 files changed, 29 insertions(+), 8 deletions(-) diff --git a/ChangeLog b/ChangeLog index cf6959d..ea7b3d4 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,11 @@ +2019-05-15 Mark Wielaard + + [BZ# 24476] + * dlfcn/dlerror.c (__dlerror_main_freeres): Guard using + __libc_once_get (once) and static_buf == NULL. + (__dlerror): Check we have a valid key, set result to static_buf + otherwise. + 2019-05-15 Andreas Schwab [BZ #20568] diff --git a/dlfcn/dlerror.c b/dlfcn/dlerror.c index 2737658..ca42c12 100644 --- a/dlfcn/dlerror.c +++ b/dlfcn/dlerror.c @@ -72,9 +72,16 @@ __dlerror (void) __libc_once (once, init); /* Get error string. */ - result = (struct dl_action_result *) __libc_getspecific (key); - if (result == NULL) - result = &last_result; + if (static_buf != NULL) + result = static_buf; + else + { + /* init () has been run and we don't use the static buffer. + So we have a valid key. */ + result = (struct dl_action_result *) __libc_getspecific (key); + if (result == NULL) + result = &last_result; + } /* Test whether we already returned the string. */ if (result->returned != 0) @@ -230,13 +237,19 @@ free_key_mem (void *mem) void __dlerror_main_freeres (void) { - void *mem; /* Free the global memory if used. */ check_free (&last_result); - /* Free the TSD memory if used. */ - mem = __libc_getspecific (key); - if (mem != NULL) - free_key_mem (mem); + + if (__libc_once_get (once) && static_buf == NULL) + { + /* init () has been run and we don't use the static buffer. + So we have a valid key. */ + void *mem; + /* Free the TSD memory if used. */ + mem = __libc_getspecific (key); + if (mem != NULL) + free_key_mem (mem); + } } struct dlfcn_hook *_dlfcn_hook __attribute__((nocommon)); -- 2.7.4