From: Rabin Vincent <rabinv@axis.com>
Date: Mon, 17 Apr 2017 15:03:44 +0000 (-0300)
Subject: [BZ 21357] unwind-dw2-fde: Call free() outside of unwind mutex
X-Git-Tag: glibc-2.26~605
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2604882cefd3281679b8177245fdebc7061b8695;p=thirdparty%2Fglibc.git

[BZ 21357] unwind-dw2-fde: Call free() outside of unwind mutex

__deregister_frame_info_bases() calls free() while holding a mutex which
is also used from _Unwind_Find_FDE().  This leads to a deadlock if
AddressSanitizer uses _Unwind_Backtrace() from its free()
implementation.

Checked on mips-linux-gnu and x86_64-linux-gnu.

	[BZ #21357]
	* sysdeps/generic/unwind-dw2-fde.c (__deregister_frame_info_bases):
	Call free() outside of mutex.
---

diff --git a/ChangeLog b/ChangeLog
index b209f9c8cc5..bfda0e13ddd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2017-04-17  Rabin Vincent  <rabinv@axis.com>
+
+	[BZ #21357]
+	* sysdeps/generic/unwind-dw2-fde.c (__deregister_frame_info_bases):
+	Call free() outside of mutex.
+
 2017-04-13  Florian Weimer  <fweimer@redhat.com>
 
 	* csu/check_fds.c (__libc_check_standard_fds): Assume O_NOFOLLOW
diff --git a/sysdeps/generic/unwind-dw2-fde.c b/sysdeps/generic/unwind-dw2-fde.c
index 2f0bcd2ee9a..104a2552b4d 100644
--- a/sysdeps/generic/unwind-dw2-fde.c
+++ b/sysdeps/generic/unwind-dw2-fde.c
@@ -202,6 +202,7 @@ __deregister_frame_info_bases (void *begin)
 {
   struct object **p;
   struct object *ob = 0;
+  struct fde_vector *tofree = NULL;
 
   /* If .eh_frame is empty, we haven't registered.  */
   if (*(uword *) begin == 0)
@@ -225,7 +226,7 @@ __deregister_frame_info_bases (void *begin)
 	  {
 	    ob = *p;
 	    *p = ob->next;
-	    free (ob->u.sort);
+	    tofree = ob->u.sort;
 	    goto out;
 	  }
       }
@@ -244,6 +245,7 @@ __deregister_frame_info_bases (void *begin)
 
  out:
   __gthread_mutex_unlock (&object_mutex);
+  free (tofree);
   return (void *) ob;
 }
 hidden_def (__deregister_frame_info_bases)