public inbox for libc-stable@sourceware.org
 help / color / mirror / Atom feed
* [2.28 COMMITTED] dlfcn: Guard __dlerror_main_freeres with __libc_once_get (once) [BZ#24476]
@ 2019-01-01  0:00 Mark Wielaard
  0 siblings, 0 replies; only message in thread
From: Mark Wielaard @ 2019-01-01  0:00 UTC (permalink / raw)
  To: libc-stable; +Cc: Mark Wielaard

From: Mark Wielaard <mark@klomp.org>

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 <carlos@redhat.com>
(cherry picked from commit 11b451c8868d8a2b0edc5dfd44fc58d9ee538be0)

diff --git a/NEWS b/NEWS
index 1da958d..8bad7b0 100644
--- a/NEWS
+++ b/NEWS
@@ -58,6 +58,7 @@ The following bugs are resolved with this release:
   [24097] Can't use 64-bit register for size_t in assembly codes for x32 (CVE-2019-6488)
   [24155] x32 memcmp can treat positive length as 0 (if sign bit in RDX is set) (CVE-2019-7309)
   [24161] __run_fork_handlers self-deadlocks in malloc/tst-mallocfork2
+  [24476] dlfcn: Guard __dlerror_main_freeres with __libc_once_get (once)
 
 Security related changes:
 
diff --git a/dlfcn/dlerror.c b/dlfcn/dlerror.c
index 96bf925..0673246 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));

^ permalink raw reply	[flat|nested] only message in thread

only message in thread, other threads:[~2019-05-16 13:23 UTC | newest]

Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-01-01  0:00 [2.28 COMMITTED] dlfcn: Guard __dlerror_main_freeres with __libc_once_get (once) [BZ#24476] Mark Wielaard

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).