[glibc/release/2.34/master] Avoid -Wuse-after-free in tests [BZ #26779].

[glibc/release/2.34/master] Avoid -Wuse-after-free in tests [BZ #26779].

[Florian Weimer]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=88b3228d9f6322b035fa89bb34f82d93b4190d48

commit 88b3228d9f6322b035fa89bb34f82d93b4190d48
Author: Martin Sebor <msebor@redhat.com>
Date:   Tue Jan 25 15:39:38 2022 -0700

    Avoid -Wuse-after-free in tests [BZ #26779].
    
    Reviewed-by: Carlos O'Donell <carlos@redhat.com>
    (cherry picked from commit c094c232eb3246154265bb035182f92fe1b17ab8)

Diff:
---
 malloc/tst-malloc-backtrace.c             |  9 +++++++++
 malloc/tst-malloc-check.c                 | 16 ++++++++++++++++
 malloc/tst-malloc-too-large.c             | 24 ++++++++++++++++++++++++
 malloc/tst-obstack.c                      |  2 +-
 malloc/tst-realloc.c                      |  8 ++++++++
 support/tst-support-open-dev-null-range.c |  3 ++-
 6 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/malloc/tst-malloc-backtrace.c b/malloc/tst-malloc-backtrace.c
index 4eb42e7f32..2ae3fb11ef 100644
--- a/malloc/tst-malloc-backtrace.c
+++ b/malloc/tst-malloc-backtrace.c
@@ -20,6 +20,7 @@
 #include <stdlib.h>
 
 #include <support/support.h>
+#include <libc-diag.h>
 
 #define SIZE 4096
 
@@ -29,7 +30,15 @@ __attribute__((noinline))
 call_free (void *ptr)
 {
   free (ptr);
+#if __GNUC_PREREQ (12, 0)
+  /* Ignore a valid warning about using a pointer made indeterminate
+     by a prior call to free().  */
+  DIAG_IGNORE_NEEDS_COMMENT (12, "-Wuse-after-free");
+#endif
   *(size_t *)(ptr - sizeof (size_t)) = 1;
+#if __GNUC_PREREQ (12, 0)
+  DIAG_POP_NEEDS_COMMENT;
+#endif
 }
 
 int
diff --git a/malloc/tst-malloc-check.c b/malloc/tst-malloc-check.c
index 6650d09cf6..c5c9254a9e 100644
--- a/malloc/tst-malloc-check.c
+++ b/malloc/tst-malloc-check.c
@@ -87,7 +87,15 @@ do_test (void)
     merror ("errno is not set correctly.");
   DIAG_POP_NEEDS_COMMENT;
 
+#if __GNUC_PREREQ (12, 0)
+  /* Ignore a valid warning about using a pointer made indeterminate
+     by a prior call to realloc().  */
+  DIAG_IGNORE_NEEDS_COMMENT (12, "-Wuse-after-free");
+#endif
   free (p);
+#if __GNUC_PREREQ (12, 0)
+  DIAG_POP_NEEDS_COMMENT;
+#endif
 
   p = malloc (512);
   if (p == NULL)
@@ -105,7 +113,15 @@ do_test (void)
     merror ("errno is not set correctly.");
   DIAG_POP_NEEDS_COMMENT;
 
+#if __GNUC_PREREQ (12, 0)
+  /* Ignore a valid warning about using a pointer made indeterminate
+     by a prior call to realloc().  */
+  DIAG_IGNORE_NEEDS_COMMENT (12, "-Wuse-after-free");
+#endif
   free (p);
+#if __GNUC_PREREQ (12, 0)
+  DIAG_POP_NEEDS_COMMENT;
+#endif
   free (q);
 
   return errors != 0;
diff --git a/malloc/tst-malloc-too-large.c b/malloc/tst-malloc-too-large.c
index a4349a9b4c..328b4a2a4f 100644
--- a/malloc/tst-malloc-too-large.c
+++ b/malloc/tst-malloc-too-large.c
@@ -95,7 +95,15 @@ test_large_allocations (size_t size)
   DIAG_POP_NEEDS_COMMENT;
 #endif
   TEST_VERIFY (errno == ENOMEM);
+#if __GNUC_PREREQ (12, 0)
+  /* Ignore a warning about using a pointer made indeterminate by
+     a prior call to realloc().  */
+  DIAG_IGNORE_NEEDS_COMMENT (12, "-Wuse-after-free");
+#endif
   free (ptr_to_realloc);
+#if __GNUC_PREREQ (12, 0)
+  DIAG_POP_NEEDS_COMMENT;
+#endif
 
   for (size_t nmemb = 1; nmemb <= 8; nmemb *= 2)
     if ((size % nmemb) == 0)
@@ -113,14 +121,30 @@ test_large_allocations (size_t size)
         test_setup ();
         TEST_VERIFY (reallocarray (ptr_to_realloc, nmemb, size / nmemb) == NULL);
         TEST_VERIFY (errno == ENOMEM);
+#if __GNUC_PREREQ (12, 0)
+  /* Ignore a warning about using a pointer made indeterminate by
+     a prior call to realloc().  */
+  DIAG_IGNORE_NEEDS_COMMENT (12, "-Wuse-after-free");
+#endif
         free (ptr_to_realloc);
+#if __GNUC_PREREQ (12, 0)
+  DIAG_POP_NEEDS_COMMENT;
+#endif
 
         ptr_to_realloc = malloc (16);
         TEST_VERIFY_EXIT (ptr_to_realloc != NULL);
         test_setup ();
         TEST_VERIFY (reallocarray (ptr_to_realloc, size / nmemb, nmemb) == NULL);
         TEST_VERIFY (errno == ENOMEM);
+#if __GNUC_PREREQ (12, 0)
+  /* Ignore a warning about using a pointer made indeterminate by
+     a prior call to realloc().  */
+  DIAG_IGNORE_NEEDS_COMMENT (12, "-Wuse-after-free");
+#endif
         free (ptr_to_realloc);
+#if __GNUC_PREREQ (12, 0)
+  DIAG_POP_NEEDS_COMMENT;
+#endif
       }
     else
       break;
diff --git a/malloc/tst-obstack.c b/malloc/tst-obstack.c
index ee1385d0f7..7d700c4f9a 100644
--- a/malloc/tst-obstack.c
+++ b/malloc/tst-obstack.c
@@ -21,8 +21,8 @@ verbose_malloc (size_t size)
 static void
 verbose_free (void *buf)
 {
-  free (buf);
   printf ("free (%p)\n", buf);
+  free (buf);
 }
 
 static int
diff --git a/malloc/tst-realloc.c b/malloc/tst-realloc.c
index c89ac07e19..80711beab1 100644
--- a/malloc/tst-realloc.c
+++ b/malloc/tst-realloc.c
@@ -138,8 +138,16 @@ do_test (void)
   if (ok == 0)
     merror ("first 16 bytes were not correct after failed realloc");
 
+#if __GNUC_PREREQ (12, 0)
+  /* Ignore a valid warning about using a pointer made indeterminate
+     by a prior call to realloc().  */
+  DIAG_IGNORE_NEEDS_COMMENT (12, "-Wuse-after-free");
+#endif
   /* realloc (p, 0) frees p (C89) and returns NULL (glibc).  */
   p = realloc (p, 0);
+#if __GNUC_PREREQ (12, 0)
+  DIAG_POP_NEEDS_COMMENT;
+#endif
   if (p != NULL)
     merror ("realloc (p, 0) returned non-NULL.");
 
diff --git a/support/tst-support-open-dev-null-range.c b/support/tst-support-open-dev-null-range.c
index 8e29def1ce..80c97e5158 100644
--- a/support/tst-support-open-dev-null-range.c
+++ b/support/tst-support-open-dev-null-range.c
@@ -39,10 +39,11 @@ check_path (int fd)
   char file_path[PATH_MAX];
   ssize_t file_path_length
     = readlink (proc_fd_path, file_path, sizeof (file_path));
-  free (proc_fd_path);
   if (file_path_length < 0)
     FAIL_EXIT1 ("readlink (%s, %p, %zu)", proc_fd_path, file_path,
 		sizeof (file_path));
+
+  free (proc_fd_path);
   file_path[file_path_length] = '\0';
   TEST_COMPARE_STRING (file_path, "/dev/null");
 }