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authorJoseph Myers <joseph@codesourcery.com>2023-04-26 17:14:18 +0000
committerSamuel Thibault <samuel.thibault@ens-lyon.org>2023-04-27 01:27:28 +0200
commitaf16a59ee1f72392b88d439d8f802c9844f86f4f (patch)
treeb1545d20010800e1c8368b64d0ceeb854d2351d3 /sysdeps/mach
parentbcca5ae8049efd98ef11f45cf0f1fcea661b3cc1 (diff)
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Fix Hurd getcwd build with GCC >= 13
The build of glibc for i686-gnu has been failing for a while with GCC
mainline / GCC 13:

../sysdeps/mach/hurd/getcwd.c: In function '__hurd_canonicalize_directory_name_internal':
../sysdeps/mach/hurd/getcwd.c:242:48: error: pointer 'file_name' may be used after 'realloc' [-Werror=use-after-free]
  242 |                   file_namep = &buf[file_namep - file_name + size / 2];
      |                                     ~~~~~~~~~~~^~~~~~~~~~~
../sysdeps/mach/hurd/getcwd.c:236:25: note: call to 'realloc' here
  236 |                   buf = realloc (file_name, size);
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~

Fix by doing the subtraction before the reallocation.

Tested with build-many-glibcs.py for i686-gnu.

[samuel.thibault@ens-lyon.rg: Removed mention of this being a bug]

Message-Id: <18587337-7815-4056-ebd0-724df262d591@codesourcery.com>
Diffstat (limited to 'sysdeps/mach')
-rw-r--r--sysdeps/mach/hurd/getcwd.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/sysdeps/mach/hurd/getcwd.c b/sysdeps/mach/hurd/getcwd.c
index f24b35b380..cd3aedd9cd 100644
--- a/sysdeps/mach/hurd/getcwd.c
+++ b/sysdeps/mach/hurd/getcwd.c
@@ -222,8 +222,9 @@ __hurd_canonicalize_directory_name_internal (file_t thisdir,
       found:
 	{
 	  /* Prepend the directory name just discovered.  */
+	  size_t offset = file_namep - file_name;
 
-	  if (file_namep - file_name < d->d_namlen + 1)
+	  if (offset < d->d_namlen + 1)
 	    {
 	      if (orig_size > 0)
 		{
@@ -239,7 +240,7 @@ __hurd_canonicalize_directory_name_internal (file_t thisdir,
 		      free (file_name);
 		      return NULL;
 		    }
-		  file_namep = &buf[file_namep - file_name + size / 2];
+		  file_namep = &buf[offset + size / 2];
 		  file_name = buf;
 		  /* Move current contents up to the end of the buffer.
 		     This is guaranteed to be non-overlapping.  */