commit c259196b5005812aa3294dbf4eeca29b266a4522
Author: Florian Weimer <fweimer@redhat.com>
Date:   Fri Mar 1 18:53:03 2019 +0100

    elf/tst-big-note: Improve accuracy of test [BZ #20419]
    
    It is possible that the link editor injects an allocated ABI tag note
    before the artificial, allocated large note in the test.  Note parsing
    in open_verify stops when the first ABI tag note is encountered, so if
    the ABI tag note comes first, the problematic code is not actually
    exercised.
    
    Also tweak the artificial note so that it is a syntactically valid
    4-byte aligned note, in case the link editor tries to parse notes and
    process them.
    
    Improves the testing part of commit 0065aaaaae51cd60210ec3a7e13.
    
    Reviewed-by: Carlos O'Donell <carlos@redhat.com>

(Minor adjustment for Makefile conflict.)

diff --git a/elf/Makefile b/elf/Makefile
index b46b3a0e3542a06f..2b2662d5cf96c437 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -244,8 +244,8 @@ extra-test-objs += $(addsuffix .os,$(strip $(modules-names)))
 # We need this variable to be sure the test modules get the right CPPFLAGS.
 test-extras += $(modules-names)
 
-# filtmod1.so has a special rule
-modules-names-nobuild := filtmod1
+# filtmod1.so, tst-big-note-lib.so have special rules.
+modules-names-nobuild := filtmod1 tst-big-note-lib
 
 ifneq (no,$(multi-arch))
 tests-static += ifuncmain1static ifuncmain1picstatic \
@@ -1239,3 +1239,8 @@ $(objpfx)tst-audit12mod1.so: $(objpfx)tst-audit12mod2.so
 LDFLAGS-tst-audit12mod2.so = -Wl,--version-script=tst-audit12mod2.map
 
 $(objpfx)tst-big-note: $(objpfx)tst-big-note-lib.so
+# Avoid creating an ABI tag note, which may come before the
+# artificial, large note in tst-big-note-lib.o and invalidate the
+# test.
+$(objpfx)tst-big-note-lib.so: $(objpfx)tst-big-note-lib.o
+	$(LINK.o) -shared -o $@ $(LDFLAGS.so) $<
diff --git a/elf/tst-big-note-lib.S b/elf/tst-big-note-lib.S
index 6b514a03cc686141..c97590ccb05e9b2e 100644
--- a/elf/tst-big-note-lib.S
+++ b/elf/tst-big-note-lib.S
@@ -20,7 +20,13 @@
    On a typical Linux system with 8MiB "ulimit -s", that was enough
    to trigger stack overflow in open_verify.  */
 
+#define NOTE_SIZE 8*1024*1024
+
 .pushsection .note.big,"a"
-.balign 4
-.fill 8*1024*1024, 1, 0
+	.balign 4
+	.long 5 		/* n_namesz.  Length of "GLIBC".  */
+	.long NOTE_SIZE		/* n_descsz.  */
+	.long 0			/* n_type.  */
+	.ascii "GLIBC\0\0\0"	/* Name and alignment to four bytes.  */
+	.fill NOTE_SIZE, 1, 0
 .popsection