From: Florian Weimer <fweimer@redhat.com>
Date: Wed, 10 Jan 2018 12:18:04 +0000 (+0100)
Subject: nptl: Open libgcc.so with RTLD_NOW during pthread_cancel [BZ #22636]
X-Git-Tag: glibc-2.27~151
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=f993b8754080ac7572b692870e926d8b493db16c;p=thirdparty%2Fglibc.git

nptl: Open libgcc.so with RTLD_NOW during pthread_cancel [BZ #22636]

Disabling lazy binding reduces stack usage during unwinding.

Note that RTLD_NOW only makes a difference if libgcc.so has not
already been loaded, so this is only a partial fix.

Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
---

diff --git a/ChangeLog b/ChangeLog
index b1da834f8e0..10658831cc2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+2018-01-10  Florian Weimer  <fweimer@redhat.com>
+
+	[BZ #22636]
+	* sysdeps/nptl/unwind-forcedunwind.c (pthread_cancel_init): Open
+	libgcc.so with RTLD_NOW, to avoid lazy binding during unwind.
+
 2018-01-10  Samuel Thibault  <samuel.thibault@ens-lyon.org>
 
 	* hurd/hurd/fd.h: Include <fcntl.h>
diff --git a/sysdeps/nptl/unwind-forcedunwind.c b/sysdeps/nptl/unwind-forcedunwind.c
index ab4350de99f..67b8e74b536 100644
--- a/sysdeps/nptl/unwind-forcedunwind.c
+++ b/sysdeps/nptl/unwind-forcedunwind.c
@@ -49,7 +49,7 @@ pthread_cancel_init (void)
       return;
     }
 
-  handle = __libc_dlopen (LIBGCC_S_SO);
+  handle = __libc_dlopen_mode (LIBGCC_S_SO, RTLD_NOW | __RTLD_DLOPEN);
 
   if (handle == NULL
       || (resume = __libc_dlsym (handle, "_Unwind_Resume")) == NULL